$69+ 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 10/6. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Sep 25 — Oct 21
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 26, 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 26, 2026.
This Delta deal was found by Cheapflights users on 8/23. 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 10/145:30 am -
1 stop6h 02m
Mon 10/192:22 pm -
1 stop6h 30m
Deal found 8/23![Delta logo]()
$238
This Southwest deal was found by Cheapflights users on 8/23. 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 10/2211:10 am -
2 stops8h 35m
Mon 10/265:50 pm -
1 stop9h 45m
Deal found 8/23![Southwest logo]()
$244
This Southwest deal was found by Cheapflights users on 8/25. 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 9/235:20 am -
1 stop10h 35m
Wed 9/308:25 am -
2 stops10h 25m
Deal found 8/25![Southwest logo]()
$248
This Southwest deal was found by Cheapflights users on 8/24. 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 10/16:50 pm -
1 stop13h 10m
Tue 10/65:20 am -
2 stops10h 15m
Deal found 8/24![Southwest logo]()
$250
This Southwest deal was found by Cheapflights users on 8/24. 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 9/2411:05 pm -
1 stop8h 10m
Wed 10/72:35 pm -
2 stops9h 05m
Deal found 8/24![Southwest logo]()
$253
This Kiwi.com deal was found by Cheapflights users on 8/24. 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
Tue 9/2212:17 pm -
2 stops28h 51m
Deal found 8/24![Frontier logo]()
$255
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 stops23h 27m
Mon 9/288:10 pm -
1 stop20h 58m
Deal found 8/23![Frontier logo]()
$256
This Southwest deal was found by Cheapflights users on 8/22. 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 11/511:20 am -
2 stops11h 30m
Mon 11/95:05 am -
2 stops10h 50m
Deal found 8/22![Southwest logo]()
$258
This American Airlines deal was found by Cheapflights users on 8/25. 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 11/511:34 pm -
1 stop9h 13m
Sun 11/86:00 am -
1 stop10h 20m
Deal found 8/25![American Airlines logo]()
$259
This Southwest deal was found by Cheapflights users on 8/24. 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 10/164:15 pm -
1 stop5h 30m
Mon 10/195:50 pm -
2 stops8h 45m
Deal found 8/24![Southwest logo]()
$261
This Southwest deal was found by Cheapflights users on 8/23. 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 9/2610:50 am -
2 stops8h 50m
Tue 9/295:55 am -
1 stop9h 05m
Deal found 8/23![Southwest logo]()
$262
This Delta deal was found by Cheapflights users on 8/25. 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 10/2412:10 am -
1 stop7h 34m
Sun 11/87:45 am -
1 stop9h 05m
Deal found 8/25![Delta logo]()
$263
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 26, 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 26, 2026.
This Southwest deal was found by Cheapflights users on 8/24. 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 10/68:55 am -
1 stop6h 50m
Thu 10/152:30 pm -
2 stops12h 05m
Deal found 8/24![Southwest logo]()
$270
This American Airlines deal was found by Cheapflights users on 8/25. 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 9/303:41 pm -
1 stop6h 27m
Sat 10/312:17 pm -
1 stop9h 31m
Deal found 8/25![American Airlines logo]()
$281
This Delta deal was found by Cheapflights users on 8/20. 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 10/37:15 am -
Nonstop4h 14m
Thu 10/2212:50 pm -
Nonstop4h 35m
Deal found 8/20![Delta logo]()
$287
This United Airlines deal was found by Cheapflights users on 8/22. 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 10/73:18 pm -
1 stop7h 37m
Tue 10/138:12 pm -
Nonstop4h 44m
Deal found 8/22![United Airlines logo]()
$287
This Alaska Airlines deal was found by Cheapflights users on 8/22. 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 9/128:49 pm -
1 stop14h 33m
Sat 10/179:00 am -
Nonstop4h 44m
Deal found 8/22![Alaska Airlines logo]()
$297
This Kiwi.com deal was found by Cheapflights users on 8/25. 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 11/412:14 pm -
1 stop29h 48m
Sun 11/88:37 pm -
1 stop15h 08m
Deal found 8/25![Multiple Airlines logo]()
$339
This Southwest deal was found by Cheapflights users on 8/25. 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 10/163:10 pm -
1 stop7h 25m
Mon 10/195:50 pm -
2 stops8h 45m
Deal found 8/25![Southwest logo]()
$281
This Delta deal was found by Cheapflights users on 8/22. 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 9/167:15 am -
Nonstop4h 14m
Mon 9/215:44 pm -
Nonstop4h 36m
Deal found 8/22![Delta logo]()
$287
This United Airlines deal was found by Cheapflights users on 8/21. 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 10/297:00 am -
Nonstop4h 10m
Tue 11/38:30 pm -
Nonstop4h 47m
Deal found 8/21![United Airlines logo]()
$287
This Southwest deal was found by Cheapflights users on 8/22. 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 9/196:25 pm -
1 stop9h 30m
Sat 9/266:25 pm -
Nonstop4h 30m
Deal found 8/22![Southwest logo]()
$287
This Alaska Airlines deal was found by Cheapflights users on 8/21. 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 8/21![Alaska Airlines logo]()
$317
This United Airlines deal was found by Cheapflights users on 8/21. 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 10/201:56 pm -
1 stop7h 02m
Sat 10/2410:43 am -
2 stops11h 54m
Deal found 8/21![United Airlines logo]()
$303
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 8/23![Multiple Airlines logo]()
$340
This American Airlines deal was found by Cheapflights users on 8/25. 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 11/115:10 am -
1 stop6h 52m
Mon 11/166:59 pm -
1 stop7h 36m
Deal found 8/25![American Airlines logo]()
$348
This Southwest deal was found by Cheapflights users on 8/22. 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 10/1212:10 am -
1 stop8h 40m
Sat 10/178:25 am -
2 stops13h 35m
Deal found 8/22![Southwest logo]()
$289
This Alaska Airlines deal was found by Cheapflights users on 8/21. 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 10/225:49 pm -
Nonstop4h 10m
Sun 10/257:49 pm -
1 stop15h 39m
Deal found 8/21![Alaska Airlines logo]()
$337
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 10/2712:14 pm -
2 stops23h 03m
Sun 11/88:37 pm -
1 stop15h 08m
Deal found 8/23![Multiple Airlines logo]()
$355
This Delta deal was found by Cheapflights users on 8/22. 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 10/1211:59 pm -
1 stop9h 27m
Wed 10/214:26 pm -
1 stop9h 26m
Deal found 8/22![Delta logo]()
$356
This United Airlines deal was found by Cheapflights users on 8/23. 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 11/57:35 pm -
2 stops14h 35m
Sun 11/88:00 am -
1 stop8h 39m
Deal found 8/23![United Airlines logo]()
$332
This Southwest deal was found by Cheapflights users on 8/25. 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 9/234:10 pm -
1 stop11h 30m
Wed 9/306:30 am -
1 stop8h 30m
Deal found 8/25![Southwest logo]()
$302
This Alaska Airlines deal was found by Cheapflights users on 8/25. 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 12/310:52 am -
Nonstop4h 09m
Tue 12/82:54 pm -
1 stop9h 13m
Deal found 8/25![Alaska Airlines logo]()
$340
This American Airlines deal was found by Cheapflights users on 8/24. 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 10/163:14 pm -
1 stop6h 45m
Mon 10/193:58 pm -
1 stop10h 12m
Deal found 8/24![American Airlines logo]()
$381
This Delta deal was found by Cheapflights users on 8/21. 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 10/1511:45 am -
1 stop8h 45m
Sun 10/185:04 pm -
1 stop8h 48m
Deal found 8/21![Delta logo]()
$359
This United Airlines deal was found by Cheapflights users on 8/25. 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 11/122:30 pm -
1 stop6h 54m
Mon 11/168:30 am -
2 stops14h 26m
Deal found 8/25![United Airlines logo]()
$332
This Southwest deal was found by Cheapflights users on 8/21. 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 10/2812:10 am -
Nonstop3h 55m
Tue 11/31:20 pm -
2 stops10h 55m
Deal found 8/21![Southwest logo]()
$302
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 10/2712:14 pm -
2 stops23h 03m
Thu 11/58:52 pm -
1 stop14h 53m
Deal found 8/23![Multiple Airlines logo]()
$378
This KAYAK deal was found by Cheapflights users on 8/25. 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 KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/126:03 pm -
Nonstop3h 56m
Thu 10/157:29 am -
1 stop10h 14m
Deal found 8/25![American Airlines logo]()
$393
This Delta deal was found by Cheapflights users on 8/22. 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 9/236:00 am -
2 stops14h 34m
Tue 10/612:13 pm -
2 stops11h 52m
Deal found 8/22![Delta logo]()
$363
This Alaska Airlines deal was found by Cheapflights users on 8/25. 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 1/1511:45 am -
Nonstop4h 14m
Mon 1/188:00 am -
Nonstop4h 47m
Deal found 8/25![Alaska Airlines logo]()
$367
This Southwest deal was found by Cheapflights users on 8/22. 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.
Sun 9/205:35 am -
Nonstop3h 55m
Wed 9/303:30 pm -
Nonstop4h 25m
Deal found 8/22![Southwest logo]()
$317
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated August 26, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated August 26, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 8/22. 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 9/114:27 pm -
1 stop24h 50m
Mon 9/148:10 pm -
1 stop20h 58m
Deal found 8/22![Frontier logo]()
$274
This CheapOair deal was found by Cheapflights users on 8/21. 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 9/119:45 pm -
1 stop29h 53m
Fri 9/188:55 pm -
1 stop14h 47m
Deal found 8/21![Frontier logo]()
$280
This Kiwi.com deal was found by Cheapflights users on 8/24. 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
Tue 9/2212:17 pm -
2 stops28h 51m
Deal found 8/24![Frontier logo]()
$255
This Kiwi.com deal was found by Cheapflights users on 8/24. 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
Sat 9/198:10 pm -
1 stop20h 58m
Deal found 8/24![Frontier logo]()
$265
This Kiwi.com deal was found by Cheapflights users on 8/24. 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 9/158:15 pm -
2 stops21h 02m
Mon 9/218:10 pm -
1 stop20h 58m
Deal found 8/24![Frontier logo]()
$280
This Kiwi.com deal was found by Cheapflights users on 8/21. 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 9/188:15 pm -
2 stops26h 08m
Wed 9/236:30 am -
1 stop10h 38m
Deal found 8/21![Frontier logo]()
$279
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 9/219:45 pm -
2 stops37h 25m
Mon 9/288:10 pm -
1 stop20h 58m
Deal found 8/23![Frontier logo]()
$279
This Southwest deal was found by Cheapflights users on 8/23. 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 9/235:20 am -
1 stop7h 50m
Mon 9/288:25 am -
Nonstop4h 20m
Deal found 8/23![Southwest logo]()
$238
This Southwest deal was found by Cheapflights users on 8/25. 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 9/235:20 am -
1 stop10h 35m
Wed 9/308:25 am -
2 stops10h 25m
Deal found 8/25![Southwest logo]()
$248
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 stops23h 27m
Mon 9/288:10 pm -
1 stop20h 58m
Deal found 8/23![Frontier logo]()
$256
This Southwest deal was found by Cheapflights users on 8/24. 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 9/2411:05 pm -
1 stop8h 10m
Wed 9/308:25 am -
2 stops10h 25m
Deal found 8/24![Southwest logo]()
$253
This Southwest deal was found by Cheapflights users on 8/23. 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 9/2610:50 am -
2 stops8h 50m
Tue 9/295:55 am -
1 stop9h 05m
Deal found 8/23![Southwest 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 26, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated August 26, 2026.
This Southwest deal was found by Cheapflights users on 8/25. 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 10/612:10 am -
1 stop7h 05m
Deal found 8/25![Southwest logo]()
$69
This Southwest deal was found by Cheapflights users on 8/25. 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 11/59:25 pm -
1 stop12h 25m
Deal found 8/25![Southwest logo]()
$74
This American Airlines deal was found by Cheapflights users on 8/24. 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 9/303:41 pm -
1 stop6h 46m
Deal found 8/24![American Airlines logo]()
$80
This Southwest deal was found by Cheapflights users on 8/21. 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 9/1811:00 pm -
1 stop7h 15m
Deal found 8/21![Southwest logo]()
$86
This Delta deal was found by Cheapflights users on 8/25. 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 10/2311:10 pm -
1 stop8h 34m
Deal found 8/25![Delta logo]()
$89
This American Airlines deal was found by Cheapflights users on 8/23. 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.
Mon 9/213:41 pm -
1 stop6h 46m
Deal found 8/23![American Airlines logo]()
$104
This Delta deal was found by Cheapflights users on 8/21. 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 9/2211:59 pm -
1 stop6h 41m
Deal found 8/21![Delta logo]()
$109
This Delta deal was found by Cheapflights users on 8/25. 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 10/2412:10 am -
1 stop7h 34m
Deal found 8/25![Delta logo]()
$114
This Kiwi.com deal was found by Cheapflights users on 8/25. 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 10/68:15 pm -
2 stops21h 02m
Deal found 8/25![Frontier logo]()
$116
This Kiwi.com deal was found by Cheapflights users on 8/23. 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 9/228:15 pm -
2 stops21h 02m
Deal found 8/23![Frontier logo]()
$121
This Kiwi.com deal was found by Cheapflights users on 8/21. 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 11/178:09 pm -
2 stops17h 14m
Deal found 8/21![Frontier logo]()
$129
This Kiwi.com deal was found by Cheapflights users on 8/22. 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 9/188:15 pm -
2 stops26h 08m
Deal found 8/22![Frontier logo]()
$145
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 26, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $238 (Delta) |
One-way from | $69 (Southwest) |
Popular in | June |
Cheapest in | February |
Average price | $391 |
Good round-trip deal | $372 or less |
Good one-way deal | $199 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 August 26, 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 10/6
8:55 am-5:45 pm
1 stop6h 50m
Lambert-St Louis
Thu 10/15
2:30 pm-12:35 am
2 stops12h 05m
$270
SeattlePeoria
SEA Seattle/Tacoma Intl - PIA Greater Peoria
SEAPIA
Seattle/Tacoma Intl
Wed 9/30
3:41 pm-12:08 am
1 stop6h 27m
Greater Peoria
Sat 10/3
12:17 pm-7:48 pm
1 stop9h 31m
$281
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Fri 10/16
3:10 pm-12:35 am
1 stop7h 25m
Lambert-St Louis
Mon 10/19
5:50 pm-12:35 am
2 stops8h 45m
$281
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Sat 10/3
7:15 am-1:29 pm
Nonstop4h 14m
Chicago O'Hare Intl
Thu 10/22
12:50 pm-3:25 pm
Nonstop4h 35m
$287
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Wed 10/7
3:18 pm-12:55 am
1 stop7h 37m
Chicago O'Hare Intl
Tue 10/13
8:12 pm-10:56 pm
Nonstop4h 44m
$287
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Wed 9/16
7:15 am-1:29 pm
Nonstop4h 14m
Chicago O'Hare Intl
Mon 9/21
5:44 pm-8:20 pm
Nonstop4h 36m
$287
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Thu 10/29
7:00 am-1:10 pm
Nonstop4h 10m
Chicago O'Hare Intl
Tue 11/3
8:30 pm-11:17 pm
Nonstop4h 47m
$287
SeattleChicago
SEA Seattle/Tacoma Intl - MDW Chicago Midway
SEAMDW
Seattle/Tacoma Intl
Sat 9/19
6:25 pm-5:55 am
1 stop9h 30m
Chicago Midway
Sat 9/26
6:25 pm-8:55 pm
Nonstop4h 30m
$287
SeattleSt. Louis
SEA Seattle/Tacoma Intl - STL Lambert-St Louis
SEASTL
Seattle/Tacoma Intl
Mon 10/12
12:10 am-10:50 am
1 stop8h 40m
Lambert-St Louis
Sat 10/17
8:25 am-8:00 pm
2 stops13h 35m
$289
SeattleChicago
SEA Seattle/Tacoma Intl - ORD Chicago O'Hare Intl
SEAORD
Seattle/Tacoma Intl
Sat 9/12
8:49 pm-1:22 pm
1 stop14h 33m
Chicago O'Hare Intl
Sat 10/17
9:00 am-11:44 am
Nonstop4h 44m
$297
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-PIA
SEA-RFD
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-PIA
SEA-RFD
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 26, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 3% 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 August 26, 2026.
The most flights from SEA to USIL are scheduled on a Monday (55 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (21 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 $309 and $460 in October.The cheapest round-trip price found within the last 5 days was $279 on Multiple Airlines (Oct 7-Oct 14).
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 August 22, 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 26, 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.
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Boarding
8.1
Food
7.0
Overall
8.0
Crew
8.6
Comfort
8.0
Entertainment
7.5
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
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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 26, 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 August 26, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$168 | Average$374 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$177 | Average$374 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$184 | Average$445 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$186 | Average$455 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$193 | Average$309 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$247 | Average$399 | FlexibilityNo cancel fee | On-time63% |