$77+ 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 9/9. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Sep 13 — Sep 201
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
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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 August 14, 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 August 14, 2026.
This Kiwi.com deal was found by Cheapflights users on 8/12. 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 10/97:41 pm -
1 stop21h 16m
Fri 10/234:42 pm -
Nonstop4h 28m
Deal found 8/12![Multiple Airlines logo]()
$260
This CheapOair deal was found by Cheapflights users on 8/11. 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 8/262:37 pm -
1 stop26h 36m
Tue 9/86:45 pm -
1 stop16h 57m
Deal found 8/11![Frontier logo]()
$261
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 9/309:45 pm -
1 stop11h 32m
Fri 10/23:19 pm -
Nonstop4h 22m
Deal found 8/14![Multiple Airlines logo]()
$262
This Kiwi.com deal was found by Cheapflights users on 8/10. 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 10/29:45 pm -
1 stop11h 47m
Sun 10/1110:35 am -
2 stops49h 16m
Deal found 8/10![Frontier logo]()
$263
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 8/157:06 pm -
1 stop22h 17m
Fri 9/1112:17 pm -
1 stop8h 11m
Deal found 8/14![Frontier logo]()
$264
This Kiwi.com deal was found by Cheapflights users on 8/10. 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 9/57:06 pm -
1 stop22h 07m
Wed 9/168:10 pm -
2 stops24h 26m
Deal found 8/10![Frontier logo]()
$265
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/88:48 pm -
1 stop12h 44m
Wed 9/98:10 pm -
2 stops15h 32m
Deal found 8/13![Frontier logo]()
$266
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 10/159:16 pm -
1 stop13h 19m
Thu 10/225:53 pm -
2 stops23h 19m
Deal found 8/13![Frontier logo]()
$268
This Alaska Airlines deal was found by Cheapflights users on 8/13. 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.
Thu 9/106:03 pm -
Nonstop3h 56m
Mon 9/147:36 pm -
Nonstop4h 23m
Deal found 8/13![Alaska Airlines logo]()
$269
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 8/157:06 pm -
1 stop22h 17m
Wed 9/912:17 pm -
1 stop23h 25m
Deal found 8/14![Frontier logo]()
$270
This Delta deal was found by Cheapflights users on 8/13. 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.
Wed 10/146:00 am -
1 stop8h 43m
Wed 10/212:38 pm -
1 stop9h 27m
Deal found 8/13![Delta logo]()
$271
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/99:45 pm -
1 stop11h 32m
Sat 9/128:10 pm -
2 stops24h 26m
Deal found 8/13![Frontier logo]()
$272
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 August 14, 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 August 14, 2026.
This Southwest deal was found by Cheapflights users on 8/13. 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 11/125:15 am -
2 stops9h 40m
Mon 11/162:05 pm -
2 stops9h 05m
Deal found 8/13![Southwest logo]()
$281
This United Airlines deal was found by Cheapflights users on 8/13. 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.
Mon 9/145:13 pm -
Nonstop4h 04m
Fri 9/187:00 am -
Nonstop4h 36m
Deal found 8/13![United Airlines logo]()
$282
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/57:06 pm -
2 stops17h 57m
Sun 9/139:29 pm -
1 stop14h 13m
Deal found 8/13![Multiple Airlines logo]()
$282
This Delta deal was found by Cheapflights users on 8/10. 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.
Thu 11/56:00 am -
1 stop6h 45m
Thu 11/127:00 pm -
1 stop6h 57m
Deal found 8/10![Delta logo]()
$313
This Alaska Airlines deal was found by Cheapflights users on 8/13. 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 9/167:40 am -
1 stop9h 41m
Sat 9/192:18 pm -
1 stop9h 22m
Deal found 8/13![Alaska Airlines logo]()
$317
This American Airlines deal was found by Cheapflights users on 8/11. 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 9/103:41 pm -
1 stop6h 22m
Wed 9/165:02 am -
1 stop7h 07m
Deal found 8/11![American Airlines logo]()
$356
This Kiwi.com deal was found by Cheapflights users on 8/11. 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 9/99:45 pm -
1 stop20h 54m
Sun 9/209:29 pm -
1 stop14h 13m
Deal found 8/11![Multiple Airlines logo]()
$290
This United Airlines deal was found by Cheapflights users on 8/13. 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 9/42:34 pm -
1 stop7h 25m
Mon 9/77:00 am -
Nonstop4h 35m
Deal found 8/13![United Airlines logo]()
$292
This Southwest deal was found by Cheapflights users on 8/13. 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 10/112:10 am -
Nonstop3h 55m
Tue 10/610:00 am -
1 stop10h 05m
Deal found 8/13![Southwest logo]()
$292
This Alaska Airlines deal was found by Cheapflights users on 8/13. 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 9/1212:16 am -
Nonstop4h 04m
Sat 9/261:03 pm -
Nonstop4h 38m
Deal found 8/13![Alaska Airlines logo]()
$333
This Delta deal was found by Cheapflights users on 8/10. 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.
Wed 9/235:50 pm -
Nonstop4h 07m
Sun 9/277:00 am -
Nonstop4h 35m
Deal found 8/10![Delta logo]()
$333
This Southwest deal was found by Cheapflights users on 8/11. 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.
Fri 10/1611:35 am -
2 stops11h 35m
Mon 10/197:15 pm -
1 stop8h 20m
Deal found 8/11![Southwest logo]()
$307
This American Airlines deal was found by Cheapflights users on 8/9. 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 9/243:41 pm -
1 stop6h 24m
Tue 9/2912:08 pm -
1 stop9h 40m
Deal found 8/9![American Airlines logo]()
$359
This Kiwi.com deal was found by Cheapflights users on 8/12. 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 9/294:27 pm -
2 stops18h 50m
Sun 10/49:36 pm -
1 stop14h 06m
Deal found 8/12![Multiple Airlines logo]()
$331
This United Airlines deal was found by Cheapflights users on 8/14. 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.
Thu 11/127:00 am -
1 stop6h 43m
Mon 11/169:40 am -
2 stops13h 16m
Deal found 8/14![United Airlines logo]()
$332
This Alaska Airlines deal was found by Cheapflights users on 8/11. 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 9/612:16 am -
Nonstop4h 04m
Sat 9/196:00 am -
Nonstop4h 30m
Deal found 8/11![Alaska Airlines logo]()
$337
This Southwest deal was found by Cheapflights users on 8/14. 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 10/712:05 pm -
2 stops8h 00m
Fri 10/165:30 am -
1 stop8h 15m
Deal found 8/14![Southwest logo]()
$307
This Delta deal was found by Cheapflights users on 8/11. 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 9/115:50 pm -
Nonstop4h 07m
Sun 9/137:00 am -
Nonstop4h 35m
Deal found 8/11![Delta logo]()
$358
This United Airlines deal was found by Cheapflights users on 8/11. 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 10/1011:59 pm -
1 stop8h 11m
Wed 10/148:00 am -
2 stops14h 37m
Deal found 8/11![United Airlines logo]()
$332
This Kiwi.com deal was found by Cheapflights users on 8/10. 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 10/179:16 pm -
2 stops37h 21m
Sun 10/258:53 pm -
1 stop15h 07m
Deal found 8/10![Multiple Airlines logo]()
$337
This Southwest deal was found by Cheapflights users on 8/13. 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.
Mon 9/145:15 am -
Nonstop4h 00m
Fri 9/189:20 pm -
Nonstop4h 35m
Deal found 8/13![Southwest logo]()
$312
This Alaska Airlines deal was found by Cheapflights users on 8/13. 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.
Thu 8/205:51 pm -
Nonstop4h 08m
Thu 9/36:00 am -
Nonstop4h 30m
Deal found 8/13![Alaska Airlines logo]()
$355
This American Airlines deal was found by Cheapflights users on 8/9. 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.
Wed 8/263:35 pm -
1 stop6h 24m
Sun 8/306:32 am -
1 stop10h 24m
Deal found 8/9![American Airlines logo]()
$394
This United Airlines deal was found by Cheapflights users on 8/12. 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.
Thu 11/52:30 pm -
Nonstop4h 10m
Sun 11/89:25 am -
Nonstop4h 54m
Deal found 8/12![United Airlines logo]()
$333
This Southwest deal was found by Cheapflights users on 8/13. 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 11/125:15 am -
2 stops9h 40m
Sun 11/155:45 am -
1 stop9h 30m
Deal found 8/13![Southwest logo]()
$315
This Alaska Airlines deal was found by Cheapflights users on 8/10. 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 10/108:39 am -
1 stop9h 09m
Wed 10/147:02 am -
Nonstop4h 33m
Deal found 8/10![Alaska Airlines logo]()
$357
This Kiwi.com deal was found by Cheapflights users on 8/9. 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 9/239:45 pm -
1 stop20h 54m
Sun 9/279:29 pm -
1 stop14h 13m
Deal found 8/9![Multiple Airlines logo]()
$358
This United Airlines deal was found by Cheapflights users on 8/13. 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 9/2011:00 pm -
Nonstop4h 06m
Sat 9/267:00 am -
Nonstop4h 36m
Deal found 8/13![United Airlines logo]()
$333
This Delta deal was found by Cheapflights users on 8/10. 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.
Tue 8/2511:59 pm -
1 stop8h 26m
Sat 8/295:09 pm -
1 stop8h 48m
Deal found 8/10![Delta logo]()
$429
This Kiwi.com deal was found by Cheapflights users on 8/11. 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 9/239:45 pm -
1 stop20h 54m
Thu 10/19:03 pm -
1 stop14h 39m
Deal found 8/11![Multiple Airlines logo]()
$364
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated August 14, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated August 14, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 8/157:06 pm -
1 stop22h 17m
Fri 9/1112:17 pm -
1 stop8h 11m
Deal found 8/14![Frontier logo]()
$264
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 8/157:06 pm -
1 stop22h 17m
Wed 9/912:17 pm -
1 stop23h 25m
Deal found 8/14![Frontier logo]()
$270
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 8/198:53 pm -
1 stop18h 57m
Wed 9/912:17 pm -
1 stop23h 25m
Deal found 8/14![Frontier logo]()
$274
This CheapOair deal was found by Cheapflights users on 8/11. 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 8/262:37 pm -
1 stop26h 36m
Tue 9/86:45 pm -
1 stop16h 57m
Deal found 8/11![Frontier logo]()
$261
This Kiwi.com deal was found by Cheapflights users on 8/10. 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 9/57:06 pm -
1 stop22h 07m
Wed 9/168:10 pm -
2 stops24h 26m
Deal found 8/10![Frontier logo]()
$265
This Expedia deal was found by Cheapflights users on 8/10. 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 9/512:42 pm -
Nonstop3h 56m
Wed 9/163:19 pm -
Nonstop4h 22m
Deal found 8/10![Alaska Airlines logo]()
$276
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/88:48 pm -
1 stop12h 44m
Wed 9/98:10 pm -
2 stops15h 32m
Deal found 8/13![Frontier logo]()
$266
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/88:48 pm -
1 stop12h 44m
Sat 9/128:10 pm -
2 stops24h 26m
Deal found 8/13![Frontier logo]()
$271
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/99:45 pm -
1 stop11h 32m
Sat 9/128:10 pm -
2 stops24h 26m
Deal found 8/13![Frontier logo]()
$272
This Alaska Airlines deal was found by Cheapflights users on 8/13. 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.
Thu 9/106:03 pm -
Nonstop3h 56m
Mon 9/147:36 pm -
Nonstop4h 23m
Deal found 8/13![Alaska Airlines logo]()
$269
This Expedia deal was found by Cheapflights users on 8/13. 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.
Wed 9/165:51 pm -
Nonstop4h 08m
Sun 9/208:55 pm -
1 stop14h 47m
Deal found 8/13![Multiple Airlines logo]()
$279
This Kiwi.com deal was found by Cheapflights users on 8/14. 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 9/309:45 pm -
1 stop11h 32m
Fri 10/23:19 pm -
Nonstop4h 22m
Deal found 8/14![Multiple Airlines logo]()
$262
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 August 14, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated August 14, 2026.
This Super.com deal was found by Cheapflights users on 8/12. 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.
Wed 9/99:45 pm -
1 stop11h 32m
Deal found 8/12![Frontier logo]()
$77
This Frontier deal was found by Cheapflights users on 8/11. 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 9/129:45 pm -
1 stop11h 32m
Deal found 8/11![Frontier logo]()
$78
This Kiwi.com deal was found by Cheapflights users on 8/11. 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 9/154:27 pm -
1 stop24h 50m
Deal found 8/11![Frontier logo]()
$80
This Jetabroad deal was found by Cheapflights users on 8/11. 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 Jetabroad is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/109:16 pm -
1 stop23h 23m
Deal found 8/11![Frontier logo]()
$81
This Kiwi.com deal was found by Cheapflights users on 8/12. 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 10/97:41 pm -
1 stop21h 16m
Deal found 8/12![Frontier logo]()
$83
This Kiwi.com deal was found by Cheapflights users on 8/11. 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 9/104:27 pm -
1 stop24h 50m
Deal found 8/11![Frontier logo]()
$85
This Kiwi.com deal was found by Cheapflights users on 8/12. 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 9/57:06 pm -
1 stop22h 07m
Deal found 8/12![Frontier logo]()
$87
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 9/119:45 pm -
1 stop11h 47m
Deal found 8/13![Frontier logo]()
$90
This Super.com deal was found by Cheapflights users on 8/13. 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.
Wed 9/28:48 pm -
1 stop19h 02m
Deal found 8/13![Frontier logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 8/11. 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 9/309:45 pm -
1 stop12h 30m
Deal found 8/11![Multiple Airlines logo]()
$136
This Kiwi.com deal was found by Cheapflights users on 8/13. 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 10/159:16 pm -
2 stops25h 08m
Deal found 8/13![Frontier logo]()
$144
This Southwest deal was found by Cheapflights users on 8/13. 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 9/1712:35 pm -
2 stops8h 50m
Deal found 8/13![Southwest logo]()
$144
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 August 14, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $260 (Kiwi.com) |
One-way from | $77 (Super.com) |
Popular in | June |
Cheapest in | February |
Average price | $369 |
Good round-trip deal | $379 or less |
Good one-way deal | $209 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 August 14, 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
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Thu 11/12
5:15 am-4:55 pm
2 stops9h 40m
Lambert-St Louis
Mon 11/16
2:05 pm-9:10 pm
2 stops9h 05m
$281
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Mon 9/14
5:13 pm-11:17 pm
Nonstop4h 04m
Chicago O'Hare Intl
Fri 9/18
7:00 am-9:36 am
Nonstop4h 36m
$282
SeattleChicago
SEA Seattle/Tacoma Intl - RFD Chicago Greater Rockford
SEARFD
Seattle/Tacoma Intl
Sat 9/5
7:06 pm-3:03 pm
2 stops17h 57m
Chicago Greater Rockford
Sun 9/13
9:29 pm-9:42 am
1 stop14h 13m
$282
SeattleChicago
SEA Seattle/Tacoma Intl - RFD Chicago Greater Rockford
SEARFD
Seattle/Tacoma Intl
Wed 9/9
9:45 pm-8:39 pm
1 stop20h 54m
Chicago Greater Rockford
Sun 9/20
9:29 pm-9:42 am
1 stop14h 13m
$290
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Fri 9/4
2:34 pm-11:59 pm
1 stop7h 25m
Chicago O'Hare Intl
Mon 9/7
7:00 am-9:35 am
Nonstop4h 35m
$292
SeattleChicago
SEA Seattle/Tacoma Intl - MDW Chicago Midway
SEAMDW
Seattle/Tacoma Intl
Thu 10/1
12:10 am-6:05 am
Nonstop3h 55m
Chicago Midway
Tue 10/6
10:00 am-6:05 pm
1 stop10h 05m
$292
SeattleChicago
SEA Seattle/Tacoma Intl - MDW Chicago Midway
SEAMDW
Seattle/Tacoma Intl
Fri 10/16
11:35 am-1:10 am
2 stops11h 35m
Chicago Midway
Mon 10/19
7:15 pm-1:35 am
1 stop8h 20m
$307
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Wed 10/7
12:05 pm-10:05 pm
2 stops8h 00m
Lambert-St Louis
Fri 10/16
5:30 am-11:45 am
1 stop8h 15m
$307
SeattleChicago
SEA Seattle/Tacoma Intl - MDW Chicago Midway
SEAMDW
Seattle/Tacoma Intl
Mon 9/14
5:15 am-11:15 am
Nonstop4h 00m
Chicago Midway
Fri 9/18
9:20 pm-11:55 pm
Nonstop4h 35m
$312
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Thu 11/5
6:00 am-2:45 pm
1 stop6h 45m
Lambert-St Louis
Thu 11/12
7:00 pm-11:57 pm
1 stop6h 57m
$313
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-STL
SEA-MLI
SEA-ORD
SEA-BMI
SEA-MDW
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-STL
SEA-MLI
SEA-ORD
SEA-BMI
What is the cheapest month to book a flight from Seattle to Illinois?
Currently, February is the cheapest month in which you can book a flight from Seattle to Illinois (average of $262). Flying from Seattle to Illinois in June is currently the most expensive (average of $419). 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 August 14, 2026.
It’s typically best to fly out from Seattle to Illinois at noon. Doing so could potentially save you 10% on the flight price compared to flying in the morning, which is usually more expensive.
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 August 14, 2026.
The most flights from SEA to USIL are scheduled on a Thursday (59 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (30 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
Airfare is below average for this route at the moment.
Seattle to Illinois flights typically cost between $311 and $475 in September.The cheapest round-trip price found within the last 5 days was $279 on Multiple Airlines (Sep 16-Sep 20).
How far ahead should I book a flight from Seattle to Illinois?
The price you pay for your flight from Seattle to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 60 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
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 August 8, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Tuesday at noon when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
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 August 14, 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
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Boarding
8.1
Overall
8.0
Crew
8.6
Entertainment
7.5
Food
7.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
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
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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 August 14, 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 6 airlines flying from Seattle to Illinois
Discover the top 6 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 August 14, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$137 | Average$355 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$177 | Average$367 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$182 | Average$448 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$184 | Average$444 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$193 | Average$310 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$239 | Average$383 | FlexibilityNo cancel fee | On-time63% |