$74+ Cheap flights from Seattle (SEA) to Illinois
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/6. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Oct 11 — Oct 181
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 September 11, 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 September 11, 2026.
This Southwest deal was found by Cheapflights users on 9/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/1111:20 am -
1 stop8h 35m
Tue 11/172:35 pm -
2 stops9h 40m
Deal found 9/10![Southwest logo]()
$222
This Expedia deal was found by Cheapflights users on 9/8. 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.
Fri 10/29:45 pm -
1 stop11h 47m
Mon 10/58:10 pm -
1 stop20h 58m
Deal found 9/8![Frontier logo]()
$226
This Delta deal was found by Cheapflights users on 9/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/126:00 am -
1 stop6h 41m
Thu 11/127:00 pm -
1 stop6h 59m
Deal found 9/7![Delta logo]()
$227
This American Airlines deal was found by Cheapflights users on 9/7. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/153:14 pm -
1 stop7h 05m
Mon 10/195:40 am -
1 stop7h 34m
Deal found 9/7![American Airlines logo]()
$228
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Tue 9/298:15 pm -
2 stops21h 02m
Fri 10/28:10 pm -
1 stop20h 58m
Deal found 9/9![Frontier logo]()
$231
This Southwest deal was found by Cheapflights users on 9/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1211:20 am -
2 stops11h 30m
Sun 11/156:10 am -
1 stop6h 30m
Deal found 9/10![Southwest logo]()
$232
This Southwest deal was found by Cheapflights users on 9/7. 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.
Wed 11/114:40 pm -
2 stops14h 50m
Mon 11/164:40 pm -
1 stop8h 50m
Deal found 9/7![Southwest logo]()
$233
This Southwest deal was found by Cheapflights users on 9/9. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1211:20 am -
2 stops11h 30m
Mon 11/161:20 pm -
2 stops9h 50m
Deal found 9/9![Southwest logo]()
$237
This Southwest deal was found by Cheapflights users on 9/7. 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.
Mon 10/266:50 pm -
1 stop13h 00m
Thu 10/295:50 pm -
2 stops8h 50m
Deal found 9/7![Southwest logo]()
$238
This Southwest deal was found by Cheapflights users on 9/9. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/242:15 pm -
1 stop6h 40m
Sat 10/318:05 am -
2 stops11h 45m
Deal found 9/9![Southwest logo]()
$242
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Sun 11/224:37 pm -
1 stop16h 26m
Tue 12/16:05 pm -
2 stops24h 01m
Deal found 9/10![Frontier logo]()
$243
This Kiwi.com deal was found by Cheapflights users on 9/10. 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 10/25:51 pm -
Nonstop4h 08m
Sat 10/36:30 am -
1 stop10h 38m
Deal found 9/10![Multiple Airlines logo]()
$276
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 September 11, 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 September 11, 2026.
This Southwest deal was found by Cheapflights users on 9/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/912:15 am -
1 stop8h 45m
Wed 11/1112:40 pm -
2 stops11h 35m
Deal found 9/10![Southwest logo]()
$222
This American Airlines deal was found by Cheapflights users on 9/8. 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 1/125:00 am -
1 stop8h 45m
Sat 1/1612:24 pm -
1 stop9h 40m
Deal found 9/8![American Airlines logo]()
$281
This Alaska Airlines deal was found by Cheapflights users on 9/6. 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.
Fri 1/159:23 pm -
1 stop13h 50m
Mon 1/188:00 am -
Nonstop4h 47m
Deal found 9/6![Alaska Airlines logo]()
$296
This United Airlines deal was found by Cheapflights users on 9/8. 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 10/1411:13 pm -
Nonstop4h 06m
Mon 10/197:00 am -
Nonstop4h 36m
Deal found 9/8![United Airlines logo]()
$317
This Delta deal was found by Cheapflights users on 9/9. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/211:45 am -
Nonstop4h 16m
Sat 10/105:48 pm -
Nonstop4h 46m
Deal found 9/9![Delta logo]()
$328
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Tue 10/204:27 pm -
2 stops18h 50m
Thu 10/228:20 pm -
1 stop15h 28m
Deal found 9/9![Multiple Airlines logo]()
$413
This Southwest deal was found by Cheapflights users on 9/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/2412:10 am -
1 stop7h 15m
Sat 10/3110:05 am -
2 stops9h 45m
Deal found 9/10![Southwest logo]()
$227
This Southwest deal was found by Cheapflights users on 9/7. 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.
Wed 12/95:40 am -
2 stops9h 45m
Tue 12/1511:20 am -
2 stops9h 20m
Deal found 9/7![Southwest logo]()
$227
This Southwest deal was found by Cheapflights users on 9/6. 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.
Fri 11/611:20 am -
2 stops11h 30m
Mon 11/97:20 pm -
1 stop7h 35m
Deal found 9/6![Southwest logo]()
$232
This Southwest deal was found by Cheapflights users on 9/8. 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 11/114:40 pm -
2 stops14h 50m
Mon 11/164:40 pm -
1 stop8h 50m
Deal found 9/8![Southwest logo]()
$233
This United Airlines deal was found by Cheapflights users on 9/8. 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 12/22:19 pm -
Nonstop4h 10m
Sat 12/121:12 pm -
1 stop9h 08m
Deal found 9/8![United Airlines logo]()
$323
This Alaska Airlines deal was found by Cheapflights users on 9/10. 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.
Mon 10/195:49 pm -
Nonstop4h 10m
Tue 10/272:21 pm -
1 stop10h 12m
Deal found 9/10![Alaska Airlines logo]()
$327
This Delta deal was found by Cheapflights users on 9/9. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/1610:39 am -
Nonstop4h 14m
Sat 10/2412:00 pm -
Nonstop4h 37m
Deal found 9/9![Delta logo]()
$328
This American Airlines deal was found by Cheapflights users on 9/8. 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 10/176:12 am -
1 stop6h 44m
Mon 10/1912:38 pm -
1 stop9h 37m
Deal found 9/8![American Airlines logo]()
$348
This Alaska Airlines deal was found by Cheapflights users on 9/8. 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 11/2611:40 am -
Nonstop4h 16m
Tue 12/17:55 pm -
1 stop16h 10m
Deal found 9/8![Alaska Airlines logo]()
$327
This United Airlines deal was found by Cheapflights users on 9/8. 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 10/283:49 pm -
1 stop6h 10m
Thu 10/294:20 pm -
1 stop6h 59m
Deal found 9/8![United Airlines logo]()
$337
This Alaska Airlines deal was found by Cheapflights users on 9/8. 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 10/1611:56 am -
Nonstop4h 24m
Sat 10/247:00 am -
Nonstop4h 42m
Deal found 9/8![Alaska Airlines logo]()
$328
This Kiwi.com deal was found by Cheapflights users on 9/9. 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 9/307:25 pm -
2 stops22h 48m
Sun 10/49:36 pm -
1 stop14h 06m
Deal found 9/9![Multiple Airlines logo]()
$414
This Delta deal was found by Cheapflights users on 9/8. 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 10/1411:45 am -
1 stop8h 45m
Tue 10/205:04 pm -
1 stop8h 48m
Deal found 9/8![Delta logo]()
$379
This Alaska Airlines deal was found by Cheapflights users on 9/10. 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.
Fri 10/239:08 pm -
1 stop14h 17m
Sat 10/319:00 am -
Nonstop4h 44m
Deal found 9/10![Alaska Airlines logo]()
$330
This United Airlines deal was found by Cheapflights users on 9/9. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/28:29 pm -
2 stops11h 37m
Tue 10/66:15 am -
1 stop7h 12m
Deal found 9/9![United Airlines logo]()
$364
This Delta deal was found by Cheapflights users on 9/6. 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.
Tue 10/2710:35 pm -
1 stop9h 43m
Sat 10/316:00 am -
1 stop9h 43m
Deal found 9/6![Delta logo]()
$379
This Southwest deal was found by Cheapflights users on 9/7. 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.
Mon 11/164:40 pm -
2 stops14h 55m
Thu 11/195:30 am -
1 stop7h 05m
Deal found 9/7![Southwest logo]()
$323
This United Airlines deal was found by Cheapflights users on 9/9. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/267:00 am -
1 stop6h 11m
Wed 9/306:15 am -
1 stop7h 12m
Deal found 9/9![United Airlines logo]()
$365
This American Airlines deal was found by Cheapflights users on 9/9. 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.
Fri 10/2312:04 pm -
1 stop7h 59m
Sun 11/16:59 pm -
1 stop7h 36m
Deal found 9/9![American Airlines logo]()
$443
This Kiwi.com deal was found by Cheapflights users on 9/7. 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 9/234:27 pm -
2 stops26h 12m
Sun 9/279:29 pm -
1 stop14h 13m
Deal found 9/7![Multiple Airlines logo]()
$447
This Delta deal was found by Cheapflights users on 9/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/66:00 am -
1 stop8h 22m
Wed 10/145:04 pm -
1 stop8h 48m
Deal found 9/7![Delta logo]()
$379
This Southwest deal was found by Cheapflights users on 9/10. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/912:10 am -
Nonstop3h 55m
Tue 10/135:45 pm -
1 stop6h 55m
Deal found 9/10![Southwest logo]()
$327
This American Airlines deal was found by Cheapflights users on 9/8. 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 10/1610:26 am -
1 stop9h 37m
Sun 10/187:03 pm -
1 stop7h 33m
Deal found 9/8![American Airlines logo]()
$443
This United Airlines deal was found by Cheapflights users on 9/7. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/175:00 am -
1 stop8h 20m
Sat 10/178:12 pm -
Nonstop4h 44m
Deal found 9/7![United Airlines logo]()
$367
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated September 11, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated September 11, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Tue 9/298:15 pm -
2 stops21h 02m
Fri 10/28:10 pm -
1 stop20h 58m
Deal found 9/9![Frontier logo]()
$231
This Trip.com deal was found by Cheapflights users on 9/10. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/2910:57 am -
1 stop16h 41m
Sat 10/36:30 am -
1 stop10h 38m
Deal found 9/10![Frontier logo]()
$277
This Expedia deal was found by Cheapflights users on 9/8. 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.
Fri 10/29:45 pm -
1 stop11h 47m
Mon 10/58:10 pm -
1 stop20h 58m
Deal found 9/8![Frontier logo]()
$226
This Kiwi.com deal was found by Cheapflights users on 9/10. 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 10/25:51 pm -
Nonstop4h 08m
Sat 10/36:30 am -
1 stop10h 38m
Deal found 9/10![Multiple Airlines logo]()
$276
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Sat 10/39:45 pm -
1 stop11h 32m
Mon 10/58:10 pm -
1 stop20h 58m
Deal found 9/9![Frontier logo]()
$246
This American Airlines deal was found by Cheapflights users on 9/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/1311:59 pm -
1 stop8h 51m
Sun 10/185:40 am -
1 stop7h 34m
Deal found 9/10![American Airlines logo]()
$222
This American Airlines deal was found by Cheapflights users on 9/9. 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 10/1511:59 pm -
1 stop8h 51m
Mon 10/197:10 pm -
1 stop7h 00m
Deal found 9/9![American Airlines logo]()
$227
This Southwest deal was found by Cheapflights users on 9/7. 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.
Fri 10/168:40 pm -
1 stop12h 35m
Mon 10/197:30 pm -
1 stop8h 10m
Deal found 9/7![Southwest logo]()
$232
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Sun 10/188:00 pm -
1 stop8h 34m
Sat 10/246:30 am -
1 stop10h 42m
Deal found 9/10![Frontier logo]()
$278
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Sun 10/188:00 pm -
1 stop8h 34m
Thu 10/226:30 am -
1 stop10h 42m
Deal found 9/10![Frontier logo]()
$279
This Southwest deal was found by Cheapflights users on 9/9. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/242:15 pm -
1 stop6h 40m
Sat 10/318:05 am -
2 stops11h 45m
Deal found 9/9![Southwest logo]()
$242
This Southwest deal was found by Cheapflights users on 9/7. 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.
Mon 10/268:40 pm -
1 stop13h 00m
Fri 10/305:50 pm -
2 stops8h 50m
Deal found 9/7![Southwest logo]()
$238
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 September 11, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated September 11, 2026.
This Kiwi.com deal was found by Cheapflights users on 9/10. 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.
Tue 10/64:27 pm -
1 stop29h 32m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$74
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Fri 10/234:27 pm -
1 stop24h 30m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$80
This Super.com deal was found by Cheapflights users on 9/10. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/64:27 pm -
1 stop24h 47m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![Frontier logo]()
$99
This Southwest deal was found by Cheapflights users on 9/8. 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 11/711:45 am -
1 stop6h 15m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Southwest logo]()
$104
This Delta deal was found by Cheapflights users on 9/9. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/136:00 am -
1 stop9h 19m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Delta logo]()
$109
This American Airlines deal was found by Cheapflights users on 9/10. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/152:26 pm -
1 stop7h 16m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![American Airlines logo]()
$114
This United Airlines deal was found by Cheapflights users on 9/10. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/36:00 am -
2 stops10h 05m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/10![United Airlines logo]()
$119
This Southwest deal was found by Cheapflights users on 9/9. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/85:15 am -
2 stops13h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Southwest logo]()
$120
This Delta deal was found by Cheapflights users on 9/5. 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.
Mon 11/25:30 am -
1 stop6h 02m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/5![Delta logo]()
$124
This Super.com deal was found by Cheapflights users on 9/8. 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.
Sat 11/144:27 pm -
1 stop5h 54m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Frontier logo]()
$152
This Kiwi.com deal was found by Cheapflights users on 9/8. 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 9/298:15 pm -
2 stops26h 08m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/8![Frontier logo]()
$153
This Kiwi.com deal was found by Cheapflights users on 9/9. 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.
Mon 11/28:09 pm -
2 stops26h 12m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/9![Frontier logo]()
$155
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 September 11, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $222 (Southwest) |
One-way from | $74 (Kiwi.com) |
Popular in | June |
Cheapest in | February |
Average price | $355 |
Good round-trip deal | $364 or less |
Good one-way deal | $190 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 7,457,451 searches. Data last updated September 11, 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
Tue 10/13
6:00 am-5:19 pm
1 stop9h 19m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$109
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sat 11/7
6:00 am-4:38 pm
1 stop8h 38m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$109
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sat 10/10
11:50 pm-8:53 am
1 stop7h 03m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$109
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Tue 11/10
11:47 pm-9:19 am
1 stop7h 32m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$109
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sat 12/5
5:30 am-1:36 pm
1 stop6h 06m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$109
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sat 12/5
5:30 am-6:15 pm
2 stops10h 45m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$114
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sun 11/8
7:00 am-3:43 pm
1 stop6h 43m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$114
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Thu 11/12
9:45 am-8:29 pm
1 stop8h 44m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$114
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Mon 11/9
6:00 am-4:31 pm
1 stop8h 31m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$114
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Sat 10/3
4:27 pm-11:17 am
2 stops16h 50m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$118
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-ORD
SEA-RFD
SEA-MLI
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-ORD
SEA-RFD
SEA-MLI
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 $261). 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 September 11, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 5% on the flight price compared to flying at noon, 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 September 11, 2026.
The most flights from SEA to USIL are scheduled on a Wednesday (53 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (18 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 $321 and $456 in October.The cheapest round-trip price found within the last 5 days was $276 on Multiple Airlines (Oct 2-Oct 3).
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 81 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 September 5, 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 September 11, 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.
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Crew
8.6
Entertainment
7.5
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
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 September 11, 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 7,457,451 searches. Data last updated September 11, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$168 | Average$374 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$177 | Average$373 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$183 | Average$446 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$186 | Average$464 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$193 | Average$309 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$247 | Average$401 | FlexibilityNo cancel fee | On-time63% |