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$62+ 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 1/10. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — SEA
Jan 9 — Jan 161
Fri 1/9
Fri 1/16
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 December 10, 2025.

This Frontier deal was found by Cheapflights users on 12/9. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/2110:49 pmORD - SEA
1 stop13h 22mFrontier
Tue 12/302:54 pmSEA - ORD
1 stop7h 18mFrontier
Deal found 12/9$207
This Frontier deal was found by Cheapflights users on 12/9. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/2110:49 pmORD - SEA
1 stop13h 22mFrontier
Wed 12/311:25 pmSEA - ORD
1 stop8h 47mFrontier
Deal found 12/9$208
This Kiwi.com deal was found by Cheapflights users on 12/8. 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 12/236:00 amORD - SEA
Nonstop4h 45mAlaska Airlines
Wed 1/75:50 pmSEA - ORD
Nonstop4h 00mAlaska Airlines
Deal found 12/8$230
This Frontier deal was found by Cheapflights users on 12/8. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/177:43 pmSTL - SEA
1 stop6h 27mFrontier
Thu 1/89:23 pmSEA - STL
1 stop12h 49mFrontier
Deal found 12/8$233
This CheapOair deal was found by Cheapflights users on 12/9. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/2310:10 pmSTL - SEA
1 stop17h 41mFrontier
Tue 12/302:54 pmSEA - STL
1 stop17h 08mFrontier
Deal found 12/9$234
This Alaska Airlines deal was found by Cheapflights users on 12/7. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/236:00 amORD - SEA
Nonstop4h 45mAlaska Airlines
Thu 1/158:30 amSEA - ORD
Nonstop4h 08mAlaska Airlines
Deal found 12/7$237
This Expedia deal was found by Cheapflights users on 12/8. 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.
Tue 12/236:00 amORD - SEA
Nonstop4h 45mMultiple Airlines
Wed 12/311:25 pmSEA - ORD
1 stop8h 47mMultiple Airlines
Deal found 12/8$246
This Alaska Airlines deal was found by Cheapflights users on 12/8. 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.
Tue 12/236:00 amORD - SEA
Nonstop4h 45mAlaska Airlines
Tue 1/65:20 amSEA - ORD
1 stop5h 56mAlaska Airlines
Deal found 12/8$247
This Delta deal was found by Cheapflights users on 12/9. 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.
Wed 12/246:05 amSTL - SEA
1 stop8h 53mDelta
Wed 12/3112:55 amSEA - STL
1 stop8h 17mDelta
Deal found 12/9$248
This Frontier deal was found by Cheapflights users on 12/7. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/227:00 amORD - SEA
1 stop7h 30mFrontier
Thu 1/1512:19 pmSEA - ORD
1 stop7h 05mFrontier
Deal found 12/7$253
This Frontier deal was found by Cheapflights users on 12/8. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/227:00 amORD - SEA
1 stop7h 30mFrontier
Wed 12/311:25 pmSEA - ORD
1 stop8h 47mFrontier
Deal found 12/8$255
This Frontier deal was found by Cheapflights users on 12/8. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/2110:49 pmORD - SEA
1 stop13h 22mFrontier
Thu 12/251:25 pmSEA - ORD
1 stop8h 47mFrontier
Deal found 12/8$258

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 December 10, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$177
(Southwest)

One-way from

$62
(Kiwi.com)

Popular in

December

Cheapest in

February

Average price

$343

Good round-trip deal

$257 or less

Good one-way deal

$138 or less
Provider with most accurate pricing for Chicago (CHI)-Seattle/Tacoma Intl flight deals.
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Provider most trusted by Cheapflights users for Chicago (CHI)-Seattle/Tacoma Intl flights.
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From Illinois to Seattle/Tacoma Intl
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One-way flight from Illinois to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 7% potential increase in price ($20 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 December 2025
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Price to beat on a round-trip flight from Illinois to Seattle/Tacoma Intl.
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Price to beat on a one-way flight from Illinois to Seattle/Tacoma Intl.
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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 December 10, 2025.
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

Mon 1/19

8:05 am-10:50 am

Nonstop4h 45m

Seattle/Tacoma Intl

Sun 1/25

6:35 am-12:35 pm

Nonstop4h 00m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Thu 2/26

7:00 am-9:51 am

Nonstop4h 51m

Seattle/Tacoma Intl

Mon 3/2

6:00 am-12:01 pm

Nonstop4h 01m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Thu 1/22

7:54 pm-10:43 pm

Nonstop4h 49m

Seattle/Tacoma Intl

Mon 1/26

7:00 am-1:08 pm

Nonstop4h 08m

$177

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Fri 1/23

10:35 am-1:15 pm

Nonstop4h 40m

Seattle/Tacoma Intl

Sun 2/1

6:35 am-12:35 pm

Nonstop4h 00m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 2/11

3:35 pm-6:22 pm

Nonstop4h 47m

Seattle/Tacoma Intl

Sun 2/15

5:55 pm-11:56 pm

Nonstop4h 01m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Tue 1/6

6:00 am-8:45 am

Nonstop4h 45m

Seattle/Tacoma Intl

Tue 1/13

5:50 pm-11:50 pm

Nonstop4h 00m

$177

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Tue 1/13

3:35 pm-6:14 pm

Nonstop4h 39m

Seattle/Tacoma Intl

Tue 1/20

12:35 pm-11:14 pm

1 stop8h 39m

$183

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Thu 1/8

10:05 am-5:50 pm

1 stop9h 45m

Seattle/Tacoma Intl

Thu 1/15

6:35 am-12:35 pm

Nonstop4h 00m

$187

ChicagoSeattle

MDW - SEA

MDWSEA

Chicago Midway

Fri 1/30

5:35 pm-10:30 pm

1 stop6h 55m

Seattle/Tacoma Intl

Sun 2/1

6:35 am-12:35 pm

Nonstop4h 00m

$187

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 3/4

5:29 pm-8:16 pm

Nonstop4h 47m

Seattle/Tacoma Intl

Sat 3/7

10:48 pm-12:11 pm

1 stop11h 23m

$187

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/8

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, September is the cheapest month in which you can book a flight from Illinois to Seattle (average of $113). Flying from Illinois to Seattle in December is currently the most expensive (average of $179). 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 December 10, 2025.

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 morning tend to be the most expensive. A flight in the evening could potentially save you up to 34% 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 December 16, 2024.

Travelers seeking maximum savings on their Illinois to Seattle flight should consider departing on Thursday at noon 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 December 10, 2025.

The most flights from USIL to SEA are scheduled on a Monday (40 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (28 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 45m. 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 Spirit Airlines ($42), Southwest ($64), and Frontier ($82).

  • 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: Aer Lingus (81%), Malaysia Airlines (79%), American Airlines (77%).

  • What are the cheapest flights from Illinois to Seattle?

    The cheapest flight price from Illinois to Seattle is $101. On average you can expect to pay $719. The most popular route, (Chicago O'Hare Intl - Seattle/Tacoma Intl), can usually be booked for $166.

  • 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, September is the cheapest month in which you can book a flight from Illinois to Seattle (average of $113). Flying from Illinois to Seattle in December is currently the most expensive (average of $179). 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
Olympia
Ocean Shores
Edmonds
Lynnwood
Renton
Puyallup
Kirkland
Tukwila
Kent
Cle Elum
Marysville
Leavenworth
Fife
Aberdeen
Shoreline
Centralia
Federal Way

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Alternative routes for Illinois to Seattle

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Top 8 airlines flying from Illinois to Seattle

Discover the top 8 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 December 10, 2025.
AirlineCheapestAverageFlexibilityOn-time
Hawaiian AirlinesCheapest$91Average$251FlexibilityNo cancel feeOn-time85%
Spirit AirlinesCheapest$105Average$202FlexibilityNo cancel feeOn-time65%
DeltaCheapest$120Average$304FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$142Average$264FlexibilityNo cancel feeOn-time62%
Alaska AirlinesCheapest$169Average$440FlexibilityNo cancel feeOn-time75%
American AirlinesCheapest$175Average$457FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$177Average$429FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$189Average$424FlexibilityNo cancel feeOn-time63%

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