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$66+ Cheap flights from Illinois to Seattle (SEA)

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 2/25. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — SEA
Feb 28 — Mar 71
Sat 2/28
Sat 3/7
1 adult, Economy
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Cheap flight deals from Illinois to Seattle

Cheapest flights from Illinois to Seattle
Explore the most affordable flight options available from Illinois to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on January 29, 2026.

This Kiwi.com deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” 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 2/271:59 pm
STL
-
SEA
1 stop24h 02m
Frontier
Tue 3/37:33 pm
SEA
-
STL
2 stops18h 20m
Frontier
Deal found 1/27$172
This Kiwi.com deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 3/78:12 pm
STL
-
SEA
1 stop16h 07m
Frontier
Fri 3/1312:24 pm
SEA
-
STL
1 stop19h 25m
Frontier
Deal found 1/28$173
This Southwest deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 3/139:55 pm
MDW
-
SEA
Nonstop4h 35m
Southwest
Sun 3/2211:55 pm
SEA
-
MDW
Nonstop3h 55m
Southwest
Deal found 1/28$177
This United Airlines deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 3/68:01 pm
ORD
-
SEA
Nonstop4h 44m
United Airlines
Sun 3/87:00 am
SEA
-
ORD
Nonstop4h 06m
United Airlines
Deal found 1/28$177
This Delta deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 4/216:45 pm
STL
-
SEA
1 stop7h 14m
Delta
Sat 5/28:20 am
SEA
-
STL
1 stop6h 30m
Delta
Deal found 1/28$177
This Kiwi.com deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” 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 3/48:10 am
ORD
-
SEA
1 stop26h 03m
Frontier
Mon 3/99:36 pm
SEA
-
ORD
1 stop30h 32m
Frontier
Deal found 1/26$180
This Kiwi.com deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 2/197:00 am
ORD
-
SEA
Nonstop4h 51m
Hawaiian Airlines
Wed 2/251:56 pm
SEA
-
ORD
1 stop8h 03m
Hawaiian Airlines
Deal found 1/28$181
This Kiwi.com deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 3/118:12 pm
STL
-
SEA
1 stop17h 07m
Frontier
Sun 3/1512:24 pm
SEA
-
STL
1 stop19h 25m
Frontier
Deal found 1/28$181
This Alaska Airlines deal was found by Cheapflights users on 1/27. Clicking the “Pick Dates” 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 3/187:24 pm
ORD
-
SEA
Nonstop4h 41m
Alaska Airlines
Wed 3/1812:35 am
SEA
-
ORD
Nonstop4h 04m
Alaska Airlines
Deal found 1/27$182
This Southwest deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 3/59:55 pm
MDW
-
SEA
Nonstop4h 35m
Southwest
Mon 3/91:20 pm
SEA
-
MDW
1 stop6h 40m
Southwest
Deal found 1/28$183
This United Airlines deal was found by Cheapflights users on 1/28. Clicking the “Pick Dates” 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 2/194:20 pm
ORD
-
SEA
Nonstop4h 43m
United Airlines
Sat 2/2112:32 pm
SEA
-
ORD
1 stop8h 54m
United Airlines
Deal found 1/28$183
This Expedia deal was found by Cheapflights users on 1/26. Clicking the “Pick Dates” 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 4/36:00 am
ORD
-
SEA
Nonstop4h 37m
Multiple Airlines
Sat 4/1112:42 pm
SEA
-
ORD
1 stop9h 56m
Multiple Airlines
Deal found 1/26$184

Find flight deals from Illinois to Seattle

Keep the following information in mind while searching for Illinois to Seattle flight deals. Data was last updated January 29, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$172
(Kiwi.com)

One-way from

$66
(Kiwi.com)

Popular in

June

Cheapest in

February

Average price

$243

Good round-trip deal

$186 or less

Good one-way deal

$108 or less
Provider with most accurate pricing for Chicago (CHI)-Seattle/Tacoma Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Chicago (CHI)-Seattle/Tacoma Intl flights.
Search Deals
From Illinois to Seattle/Tacoma Intl
Search Deals
One-way flight from Illinois to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 10% potential increase in price ($31 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($6 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in January 2026
Search Deals
Price to beat on a round-trip flight from Illinois to Seattle/Tacoma Intl.
Search Deals
Price to beat on a one-way flight from Illinois to Seattle/Tacoma Intl.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Illinois to Seattle 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 January 29, 2026.
Use the filters below to find and compare flights from Illinois to Seattle that are best for you.

Fly from

Illinois

Fly to

Seattle

Route

Depart

Return

Price

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Sat 3/14

9:40 pm-12:15 am

Nonstop4h 35m

Seattle/Tacoma Intl

Sun 3/22

11:55 pm-5:50 am

Nonstop3h 55m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 3/4

2:20 pm-5:00 pm

Nonstop4h 40m

Seattle/Tacoma Intl

Mon 3/16

5:55 pm-11:52 pm

Nonstop3h 57m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Fri 4/3

1:59 pm-4:37 pm

Nonstop4h 38m

Seattle/Tacoma Intl

Sun 4/5

11:59 pm-5:59 am

Nonstop4h 00m

$177

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Fri 3/6

9:55 pm-12:30 am

Nonstop4h 35m

Seattle/Tacoma Intl

Mon 3/9

11:55 pm-5:50 am

Nonstop3h 55m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Fri 3/6

4:20 pm-7:03 pm

Nonstop4h 43m

Seattle/Tacoma Intl

Sat 3/7

7:00 am-1:06 pm

Nonstop4h 06m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 3/4

7:40 am-10:25 am

Nonstop4h 45m

Seattle/Tacoma Intl

Sun 3/8

7:15 am-1:24 pm

Nonstop4h 09m

$177

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Fri 3/20

9:55 pm-12:30 am

Nonstop4h 35m

Seattle/Tacoma Intl

Mon 3/23

11:55 pm-5:50 am

Nonstop3h 55m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Thu 2/26

7:59 pm-10:43 pm

Nonstop4h 44m

Seattle/Tacoma Intl

Sun 3/1

7:00 am-1:06 pm

Nonstop4h 06m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 3/18

7:25 am-10:05 am

Nonstop4h 40m

Seattle/Tacoma Intl

Tue 3/24

7:15 am-1:25 pm

Nonstop4h 10m

$177

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Wed 2/25

10:35 am-1:15 pm

Nonstop4h 40m

Seattle/Tacoma Intl

Wed 3/4

6:45 am-12:40 pm

Nonstop3h 55m

$177

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/27

Showing 1-10 of 60 results
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Best time to book a flight from Illinois to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Illinois with our price prediction graph.
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 Illinois to Seattle

What is the cheapest month to book a flight from Illinois to Seattle?

Currently, October is the cheapest month in which you can book a flight from Illinois to Seattle (average of $112). Flying from Illinois to Seattle in December is currently the most expensive (average of $178). 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 IL to SEA?

Find hourly flight availability from Illinois to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated January 29, 2026.

One of the essential ways to save on airfare from Illinois to Seattle is to remain as flexible as possible. Flights that are in the afternoon tend to be the most expensive. A flight in the evening could potentially save you up to 32% on airfare.

What is the cheapest day to fly from Illinois to Seattle?

Use this chart to determine the cheapest time to fly round-trip from Illinois to Seattle. Price data was last updated on January 24, 2026.

Travelers seeking maximum savings on their Illinois to Seattle flight should consider departing on Tuesday mornings when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Illinois to Seattle

Explore weekly flight availability from Illinois to Seattle. 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 January 29, 2026.

The most flights from USIL to SEA are scheduled on a Thursday (32 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (10 on average).

Related info for your journey

Find useful and relevant information for your journey from Illinois to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Seattle from Illinois?

    Seattle/Tacoma Intl (SEA), located 11.4 mi from the city center, is the airport you fly into when you book flights from Illinois to Seattle.

  • How long is the flight from Illinois to Seattle?

    Departing from Illinois to Seattle will take you 4h 35m. The distance between Illinois and Seattle is about 1728 mi. Most flights are nonstop.

  • What are the cheapest airlines to fly from Illinois to Seattle one-way?

    The cheapest airlines for a one-way flight from Illinois to Seattle are Southwest ($64), Frontier ($82), and Alaska Airlines ($84).

  • What are the most popular routes from Illinois to Seattle?

    The most popular route from Illinois to Seattle is Chicago O'Hare Intl - Seattle/Tacoma Intl. You may also consider Chicago Midway - Seattle/Tacoma Intl or Lambert-St Louis - Seattle/Tacoma Intl.

  • What are the most reliable airlines from Illinois to Seattle?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Illinois to Seattle on time: Brussels Airlines (72%), United Airlines (66%), American Airlines (65%).

  • What are the cheapest flights from Illinois to Seattle?

    The cheapest flight price from Illinois to Seattle is $88. On average you can expect to pay $598. The most popular route, (Chicago O'Hare Intl - Seattle/Tacoma Intl), can usually be booked for $177.

  • Can I find deals for flights from Illinois to Seattle that include hotel bookings?

    Yes. In addition to deals on Illinois to Seattle flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Illinois to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Illinois to Seattle.

  • Can I find deals for business class flights from Illinois to Seattle?

    Yes. Cheapflights offers flight deals from Illinois to Seattle by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Illinois to Seattle?

    Currently, October is the cheapest month in which you can book a flight from Illinois to Seattle (average of $112). Flying from Illinois to Seattle in December is currently the most expensive (average of $178). 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.

See more FAQs

Traveling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
Tacoma
SeaTac
Lakewood
Ocean Shores
Olympia
Lynnwood
Lacey
Edmonds
Renton
Puyallup
Kirkland
Kent
Tukwila
Fife
Aberdeen
Shoreline
Marysville
Centralia
Federal Way
Chehalis

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for Illinois to Seattle

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Top 7 airlines flying from Illinois to Seattle

Discover the top 7 airlines that operate flights from Illinois to Seattle. 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 January 29, 2026.
AirlineCheapestAverageFlexibilityOn-time
Hawaiian AirlinesCheapest$84Average$237FlexibilityNo cancel feeOn-time85%
DeltaCheapest$110Average$248FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$142Average$264FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$165Average$436FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$168Average$448FlexibilityNo cancel feeOn-time75%
American AirlinesCheapest$177Average$465FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$194Average$432FlexibilityNo cancel feeOn-time63%

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