$82+ Cheap flights from Seattle (SEA) to Illinois
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 6/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
May 7 — May 141
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
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Cheapest flights from Seattle to IllinoisExplore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 7, 2026.
Explore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 7, 2026.
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/2510:57 am
SEA
- ORD
1 stop16h 38m
Multiple Airlines
Tue 4/287:21 pm
ORD
- SEA
2 stops40h 06m
Multiple Airlines
Deal found 4/3![Multiple Airlines logo]()
$223
This Frontier deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/2510:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Sat 5/27:21 pm
ORD
- SEA
1 stop24h 36m
Frontier
Deal found 4/2![Frontier logo]()
$225
This Booking.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/2810:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Wed 5/138:56 pm
ORD
- SEA
1 stop23h 39m
Frontier
Deal found 4/3![Frontier logo]()
$227
This Kiwi.com deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/3010:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Sun 5/310:50 am
ORD
- SEA
1 stop24h 37m
Multiple Airlines
Deal found 4/4![Multiple Airlines logo]()
$229
This Booking.com deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/3010:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Sun 5/310:50 am
ORD
- SEA
1 stop24h 37m
Frontier
Deal found 4/4![Frontier logo]()
$231
This Kiwi.com deal was found by Cheapflights users on 4/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/611:06 am
SEA
- ORD
1 stop17h 33m
Frontier
Sun 5/109:37 pm
ORD
- SEA
1 stop14h 12m
Frontier
Deal found 4/7![Frontier logo]()
$232
This Expedia deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/187:12 pm
SEA
- ORD
1 stop12h 33m
Multiple Airlines
Sat 4/258:00 am
ORD
- SEA
Nonstop4h 40m
Multiple Airlines
Deal found 4/2![Multiple Airlines logo]()
$233
This CheapOair deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/110:06 pm
SEA
- ORD
1 stop30h 02m
Frontier
Sun 5/37:21 pm
ORD
- SEA
1 stop24h 31m
Frontier
Deal found 4/3![Frontier logo]()
$236
This CheapOair deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2010:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Thu 4/237:21 pm
ORD
- SEA
1 stop24h 31m
Frontier
Deal found 4/6![Frontier logo]()
$237
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/2510:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Mon 4/278:58 pm
ORD
- SEA
2 stops14h 29m
Multiple Airlines
Deal found 4/3![Multiple Airlines logo]()
$238
This Gotogate deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1711:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Wed 4/227:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 4/2![Frontier logo]()
$240
This Southwest deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/2511:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 5/26:05 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 4/5![Southwest logo]()
$255
Best flights from Seattle to IllinoisDiscover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated April 7, 2026.
Discover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated April 7, 2026.
This Delta deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/257:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Sat 5/27:15 am
ORD
- SEA
Nonstop4h 49m
Delta
Deal found 4/3![Delta logo]()
$255
This Alaska Airlines deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/55:42 pm
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Wed 5/68:00 am
ORD
- SEA
Nonstop4h 40m
Alaska Airlines
Deal found 4/6![Alaska Airlines logo]()
$255
This United Airlines deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2911:59 pm
SEA
- ORD
Nonstop4h 00m
United Airlines
Wed 5/131:20 pm
ORD
- SEA
1 stop8h 28m
United Airlines
Deal found 4/3![United Airlines logo]()
$265
This Southwest deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/2311:55 pm
SEA
- STL
1 stop7h 10m
Southwest
Tue 4/285:30 am
STL
- SEA
2 stops14h 30m
Southwest
Deal found 4/6![Southwest logo]()
$272
This American Airlines deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/123:17 pm
SEA
- BMI
1 stop6h 35m
American Airlines
Tue 5/195:00 am
BMI
- SEA
1 stop7h 14m
American Airlines
Deal found 4/3![American Airlines logo]()
$411
This Kiwi.com deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/211:03 am
SEA
- PIA
2 stops22h 56m
Multiple Airlines
Mon 7/612:49 pm
PIA
- SEA
1 stop23h 46m
Multiple Airlines
Deal found 4/5![Multiple Airlines logo]()
$454
This Delta deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/27:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Sat 5/96:55 pm
ORD
- SEA
Nonstop4h 45m
Delta
Deal found 4/5![Delta logo]()
$255
This Southwest deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/185:45 am
SEA
- STL
2 stops10h 25m
Southwest
Tue 4/215:15 am
STL
- SEA
2 stops10h 20m
Southwest
Deal found 4/4![Southwest logo]()
$283
This Alaska Airlines deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/61:28 pm
SEA
- ORD
Nonstop4h 24m
Alaska Airlines
Thu 5/146:00 am
ORD
- SEA
Nonstop4h 34m
Alaska Airlines
Deal found 4/6![Alaska Airlines logo]()
$305
This Southwest deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/132:20 pm
SEA
- MDW
1 stop7h 00m
Southwest
Sat 5/166:05 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 4/2![Southwest logo]()
$285
This Delta deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/175:30 am
SEA
- STL
1 stop9h 46m
Delta
Sat 6/65:00 pm
STL
- SEA
1 stop7h 01m
Delta
Deal found 4/5![Delta logo]()
$304
This Southwest deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/25:45 am
SEA
- MDW
2 stops9h 45m
Southwest
Sat 5/96:45 am
MDW
- SEA
2 stops14h 55m
Southwest
Deal found 4/5![Southwest logo]()
$291
This United Airlines deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/110:40 pm
SEA
- CMI
1 stop8h 14m
United Airlines
Fri 7/101:32 pm
CMI
- SEA
2 stops10h 27m
United Airlines
Deal found 4/5![United Airlines logo]()
$368
This Alaska Airlines deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/99:07 am
SEA
- ORD
1 stop7h 56m
Alaska Airlines
Wed 5/132:10 pm
ORD
- SEA
1 stop9h 20m
Alaska Airlines
Deal found 4/6![Alaska Airlines logo]()
$335
This Southwest deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/66:40 am
SEA
- STL
2 stops9h 20m
Southwest
Fri 6/126:45 pm
STL
- SEA
1 stop8h 55m
Southwest
Deal found 4/4![Southwest logo]()
$304
This United Airlines deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/22:28 pm
SEA
- PIA
1 stop6h 21m
United Airlines
Wed 5/65:30 pm
PIA
- SEA
1 stop7h 17m
United Airlines
Deal found 4/2![United Airlines logo]()
$371
This American Airlines deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/21:19 pm
SEA
- EVV
1 stop8h 35m
American Airlines
Wed 5/66:33 am
EVV
- SEA
1 stop7h 56m
American Airlines
Deal found 4/5![American Airlines logo]()
$416
This Delta deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/2411:14 pm
SEA
- ORD
1 stop6h 47m
Delta
Tue 4/2812:46 pm
ORD
- SEA
Nonstop4h 34m
Delta
Deal found 4/4![Delta logo]()
$346
This Alaska Airlines deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/2412:45 pm
SEA
- STL
Nonstop4h 00m
Alaska Airlines
Sun 6/77:41 pm
STL
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 4/5![Alaska Airlines logo]()
$367
This American Airlines deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/176:00 am
SEA
- BMI
1 stop7h 15m
American Airlines
Tue 4/216:00 am
BMI
- SEA
1 stop9h 15m
American Airlines
Deal found 4/2![American Airlines logo]()
$419
This Southwest deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2911:45 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Fri 5/111:40 am
MDW
- SEA
1 stop9h 25m
Southwest
Deal found 4/5![Southwest logo]()
$315
This United Airlines deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/172:39 pm
SEA
- PIA
1 stop7h 18m
United Airlines
Tue 4/215:35 pm
PIA
- SEA
1 stop7h 07m
United Airlines
Deal found 4/2![United Airlines logo]()
$390
This United Airlines deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/188:51 am
SEA
- PIA
2 stops10h 22m
United Airlines
Mon 4/207:43 pm
PIA
- SEA
1 stop6h 51m
United Airlines
Deal found 4/2![United Airlines logo]()
$395
This Southwest deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/255:45 am
SEA
- ORD
2 stops14h 35m
Southwest
Fri 5/11:35 pm
ORD
- SEA
1 stop8h 50m
Southwest
Deal found 4/3![Southwest logo]()
$330
This Southwest deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2211:35 am
SEA
- ORD
2 stops9h 20m
Southwest
Tue 5/124:50 pm
ORD
- SEA
1 stop9h 05m
Southwest
Deal found 4/6![Southwest logo]()
$330
This United Airlines deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/217:00 am
SEA
- PAH
1 stop9h 19m
United Airlines
Sat 4/255:00 am
PAH
- SEA
1 stop8h 48m
United Airlines
Deal found 4/6![United Airlines logo]()
$404
This Alaska Airlines deal was found by Cheapflights users on 4/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/295:52 pm
SEA
- STL
Nonstop4h 02m
Alaska Airlines
Mon 6/17:41 pm
STL
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 4/5![Alaska Airlines logo]()
$457
This Delta deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/2911:35 pm
SEA
- BMI
1 stop9h 48m
Delta
Wed 6/1012:09 pm
BMI
- SEA
1 stop8h 55m
Delta
Deal found 4/4![Delta logo]()
$478
This Southwest deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/196:25 pm
SEA
- MDW
1 stop8h 35m
Southwest
Sat 5/236:15 am
MDW
- SEA
1 stop13h 40m
Southwest
Deal found 4/3![Southwest logo]()
$330
This American Airlines deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/1811:58 pm
SEA
- CMI
1 stop9h 12m
American Airlines
Mon 6/226:44 pm
CMI
- SEA
1 stop7h 32m
American Airlines
Deal found 4/3![American Airlines logo]()
$538
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated April 7, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated April 7, 2026 and is based on user searches.
This CheapOair deal was found by Cheapflights users on 4/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Fri 4/1710:55 am
ORD
- SEA
1 stop24h 32m
Frontier
Deal found 4/7![Frontier logo]()
$261
This CheapOair deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Mon 4/2010:55 am
ORD
- SEA
1 stop24h 32m
Frontier
Deal found 4/3![Frontier logo]()
$262
This Gotogate deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1711:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Wed 4/227:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 4/2![Frontier logo]()
$240
This CheapOair deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1710:59 pm
SEA
- ORD
1 stop29h 09m
Frontier
Mon 4/2010:55 am
ORD
- SEA
1 stop24h 32m
Frontier
Deal found 4/6![Frontier logo]()
$242
This CheapOair deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1710:59 pm
SEA
- ORD
1 stop29h 09m
Frontier
Fri 4/247:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 4/6![Frontier logo]()
$263
This CheapOair deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1711:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 4/3![Frontier logo]()
$271
This Delta deal was found by Cheapflights users on 4/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/195:35 am
SEA
- STL
1 stop5h 48m
Delta
Tue 4/217:00 am
STL
- SEA
1 stop7h 25m
Delta
Deal found 4/2![Delta logo]()
$273
This Delta deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2011:14 pm
SEA
- STL
1 stop8h 28m
Delta
Fri 4/2412:23 pm
STL
- SEA
1 stop6h 22m
Delta
Deal found 4/6![Delta logo]()
$272
This Southwest deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/2511:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 5/26:05 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 4/4![Southwest logo]()
$255
This Southwest deal was found by Cheapflights users on 4/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/28:30 am
SEA
- MDW
Nonstop4h 10m
Southwest
Sat 5/96:00 am
MDW
- SEA
1 stop6h 25m
Southwest
Deal found 4/7![Southwest logo]()
$265
This United Airlines deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/245:00 am
SEA
- STL
1 stop5h 42m
United Airlines
Fri 5/295:41 pm
STL
- SEA
1 stop8h 18m
United Airlines
Deal found 4/6![United Airlines logo]()
$275
This Southwest deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/286:30 am
SEA
- STL
2 stops14h 10m
Southwest
Tue 6/25:30 am
STL
- SEA
2 stops14h 30m
Southwest
Deal found 4/6![Southwest logo]()
$271
One-way flights from Seattle to IllinoisSearch for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated April 7, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated April 7, 2026.
This Kiwi.com deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/17:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 4/4![Frontier logo]()
$82
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/87:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 4/3![Frontier logo]()
$88
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/37:12 pm
SEA
- STL
1 stop22h 20m
Frontier
Deal found 4/3![Frontier logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/87:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 4/6![Frontier logo]()
$106
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/211:21 am
SEA
- STL
2 stops30h 02m
Frontier
Deal found 4/3![Frontier logo]()
$108
This Super.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1711:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Deal found 4/3![Frontier logo]()
$109
This Super.com deal was found by Cheapflights users on 4/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2710:11 pm
SEA
- ORD
1 stop29h 57m
Frontier
Deal found 4/7![Frontier logo]()
$110
This Booking.com deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/27:12 pm
SEA
- ORD
1 stop12h 33m
Frontier
Deal found 4/6![Frontier logo]()
$111
This Kiwi.com deal was found by Cheapflights users on 4/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/77:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 4/3![Frontier logo]()
$111
This CheapOair deal was found by Cheapflights users on 4/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/2411:07 am
SEA
- ORD
1 stop16h 43m
Frontier
Deal found 4/6![Frontier logo]()
$112
This Kiwi.com deal was found by Cheapflights users on 4/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/47:12 pm
SEA
- ORD
2 stops25h 49m
Frontier
Deal found 4/4![Frontier logo]()
$113
This Trip.com deal was found by Cheapflights users on 4/7. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2010:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Deal found 4/7![Frontier logo]()
$114
Find flight deals from Seattle to Illinois
Keep the following information in mind while searching for Seattle to Illinois flight deals. Data was last updated April 7, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $223 (Kiwi.com) |
One-way from | $82 (Kiwi.com) |
Popular in | December |
Cheapest in | February |
Average price | $305 |
Good round-trip deal | $345 or less |
Good one-way deal | $186 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Seattle to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 7, 2026.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 4/25
7:15 am-1:23 pm
Nonstop4h 08m
Chicago O'Hare Intl
Sat 5/2
7:15 am-10:04 am
Nonstop4h 49m
$255
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 5/5
5:42 pm-11:59 pm
Nonstop4h 17m
Chicago O'Hare Intl
Wed 5/6
8:00 am-10:40 am
Nonstop4h 40m
$255
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 5/2
7:15 am-1:23 pm
Nonstop4h 08m
Chicago O'Hare Intl
Sat 5/9
6:55 pm-9:40 pm
Nonstop4h 45m
$255
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 4/29
11:59 pm-5:59 am
Nonstop4h 00m
Chicago O'Hare Intl
Wed 5/13
1:20 pm-7:48 pm
1 stop8h 28m
$265
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Thu 4/23
11:55 pm-9:05 am
1 stop7h 10m
Lambert-St Louis
Tue 4/28
5:30 am-6:00 pm
2 stops14h 30m
$272
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Sat 4/18
5:45 am-6:10 pm
2 stops10h 25m
Lambert-St Louis
Tue 4/21
5:15 am-1:35 pm
2 stops10h 20m
$283
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Wed 5/13
2:20 pm-11:20 pm
1 stop7h 00m
Chicago Midway
Sat 5/16
6:05 pm-8:35 pm
Nonstop4h 30m
$285
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Sat 5/2
5:45 am-5:30 pm
2 stops9h 45m
Chicago Midway
Sat 5/9
6:45 am-7:40 pm
2 stops14h 55m
$291
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Sun 5/17
5:30 am-5:16 pm
1 stop9h 46m
Lambert-St Louis
Sat 6/6
5:00 pm-10:01 pm
1 stop7h 01m
$304
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Sat 6/6
6:40 am-6:00 pm
2 stops9h 20m
Lambert-St Louis
Fri 6/12
6:45 pm-1:40 am
1 stop8h 55m
$304
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Seattle to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Seattle with our price prediction graph.
SEA-ORD
SEA-MDW
SEA-STL
SEA-BMI
SEA-PIA
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Seattle to Illinois
SEA-USIL
SEA-ORD
SEA-MDW
SEA-STL
SEA-BMI
What is the cheapest month to book a flight from Seattle to Illinois?
Currently, January is the cheapest month in which you can book a flight from Seattle to Illinois (average of $93). Flying from Seattle to Illinois in March is currently the most expensive (average of $177). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
What is the cheapest time of day to fly from SEA to IL?
Find hourly flight availability from Seattle to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated April 7, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 7% on the flight price compared to flying in the morning, which is usually more expensive.
What is the cheapest day to fly from Seattle to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Seattle to Illinois. Price data was last updated on April 4, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday mornings flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Seattle to Illinois
Explore weekly flight availability from Seattle to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated April 7, 2026.
The most flights from SEA to USIL are scheduled on a Tuesday (49 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (25 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated April 7, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Southwest,Alaska Airlines, andDelta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Comfort
8.0
Food
7.0
Entertainment
7.5
Overall
8.0
Boarding
8.1
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Related info for your journey
Find useful and relevant information for your journey from Seattle to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Alternative routes for Seattle to Illinois
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Illinois by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Seattle to Illinois by cabin class
Find flights from Seattle to Illinois, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Seattle and Illinois flights
Browse other Seattle and Illinois flight options. Last updated on April 7, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Seattle to Illinois flights
Consider these flights traveling from Seattle to Illinois.
Top 7 airlines flying from Seattle to Illinois
Discover the top 7 airlines that operate flights from Seattle to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 7, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$84 | Average$247 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$109 | Average$289 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$162 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$164 | Average$417 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$169 | Average$314 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$347 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$177 | Average$423 | FlexibilityNo cancel fee | On-time71% |