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$62+ 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 2/6. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
ene. 7 — ene. 141
mié. 1/7
mié. 1/14
1 adult, Economy
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Cheap flight deals from Seattle to Illinois

Cheapest flights from Seattle to Illinois
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 diciembre 8, 2025.

This United Airlines deal was found by Cheapflights users on 12/6. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/2511:59 pmSEA - ORD
Nonstop4h 10mUnited Airlines
sáb. 1/108:50 amORD - SEA
Nonstop4h 42mUnited Airlines
Deal found 12/6$177
This deal was found by Cheapflights users on 12/6. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
lun. 12/83:40 pmSEA - ORD
1 stop6h 32mFrontier
lun. 12/157:00 amORD - SEA
1 stop6h 53mFrontier
Deal found 12/6$179
This Mytrip deal was found by Cheapflights users on 12/6. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/251:25 pmSEA - ORD
1 stop8h 47mFrontier
dom. 1/2512:07 pmORD - SEA
1 stop25h 12mFrontier
Deal found 12/6$197
This American Airlines deal was found by Cheapflights users on 12/6. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mar. 12/3012:14 amSEA - ORD
Nonstop3h 53mAmerican Airlines
lun. 1/57:25 amORD - SEA
Nonstop4h 37mAmerican Airlines
Deal found 12/6$209
This Orbitz deal was found by Cheapflights users on 12/6. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/251:25 pmSEA - ORD
1 stop8h 47mMultiple Airlines
dom. 1/258:00 amORD - SEA
Nonstop4h 46mMultiple Airlines
Deal found 12/6$210
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.
mié. 12/315:49 pmSEA - ORD
Nonstop4h 10mAlaska Airlines
lun. 1/58:58 pmORD - SEA
1 stop14h 36mAlaska Airlines
Deal found 12/7$217
This American Airlines deal was found by Cheapflights users on 12/6. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 12/2712:14 amSEA - ORD
Nonstop3h 53mAmerican Airlines
sáb. 1/107:36 pmORD - SEA
Nonstop4h 44mAmerican Airlines
Deal found 12/6$232
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.
mié. 12/245:49 pmSEA - ORD
Nonstop4h 10mAlaska Airlines
mar. 1/206:06 pmORD - SEA
Nonstop4h 50mAlaska Airlines
Deal found 12/7$237
This Expedia 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mar. 12/302:54 pmSEA - ORD
1 stop7h 18mMultiple Airlines
lun. 1/51:09 pmORD - SEA
Nonstop4h 48mMultiple Airlines
Deal found 12/7$245
This Trip.com deal was found by Cheapflights users on 12/6. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 12/1112:48 pmSEA - MDW
1 stop20h 20mFrontier
lun. 12/156:15 amMDW - SEA
1 stop12h 21mFrontier
Deal found 12/6$311
This Southwest deal was found by Cheapflights users on 12/6. 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.
mié. 12/313:05 pmSEA - MDW
1 stop12h 00mSouthwest
dom. 1/410:30 pmMDW - SEA
1 stop13h 40mSouthwest
Deal found 12/6$338
This Southwest 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
lun. 12/298:35 pmSEA - MDW
1 stop10h 10mSouthwest
lun. 1/55:15 pmMDW - SEA
1 stop9h 15mSouthwest
Deal found 12/8$342

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 diciembre 8, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$176
(Kiwi.com)

One-way from

$62
(Kiwi.com)

Popular in

December

Cheapest in

January

Average price

$381

Good round-trip deal

$324 or less

Good one-way deal

$174 or less
Provider with most accurate pricing for Seattle/Tacoma Intl-Chicago (CHI) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Chicago (CHI) flights.
Search Deals
From Seattle/Tacoma Intl to Illinois
Search Deals
One-way flight from Seattle/Tacoma Intl to Illinois
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($14 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Illinois.
Search Deals
Price to beat on a one-way flight from Seattle/Tacoma Intl to Illinois.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated diciembre 8, 2025.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.

Fly from

Seattle

Fly to

Illinois

Route

Depart

Return

Price

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

vie. 2/13

6:00 am-12:01 pm

Nonstop4h 01m

Chicago O'Hare Intl

dom. 2/15

5:29 pm-8:16 pm

Nonstop4h 47m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

sáb. 1/10

7:00 am-1:08 pm

Nonstop4h 08m

Chicago O'Hare Intl

lun. 1/12

7:54 pm-10:43 pm

Nonstop4h 49m

$177

SeattleChicago

SEA - MDW

SEAMDW

Seattle/Tacoma Intl

jue. 1/8

6:45 am-12:40 pm

Nonstop3h 55m

Chicago Midway

jue. 1/15

8:05 am-10:50 am

Nonstop4h 45m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

vie. 1/9

5:50 pm-11:50 pm

Nonstop4h 00m

Chicago O'Hare Intl

dom. 1/11

8:00 am-10:46 am

Nonstop4h 46m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

lun. 2/9

7:00 am-1:08 pm

Nonstop4h 08m

Chicago O'Hare Intl

vie. 2/13

4:20 pm-7:03 pm

Nonstop4h 43m

$177

SeattleChicago

SEA - MDW

SEAMDW

Seattle/Tacoma Intl

jue. 1/22

6:45 am-12:40 pm

Nonstop3h 55m

Chicago Midway

lun. 1/26

10:35 am-1:15 pm

Nonstop4h 40m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

mar. 1/6

7:00 am-1:08 pm

Nonstop4h 08m

Chicago O'Hare Intl

mar. 1/13

8:50 am-11:32 am

Nonstop4h 42m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

sáb. 2/14

5:55 pm-11:56 pm

Nonstop4h 01m

Chicago O'Hare Intl

lun. 2/16

7:00 am-9:51 am

Nonstop4h 51m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

mar. 1/27

8:30 am-2:38 pm

Nonstop4h 08m

Chicago O'Hare Intl

vie. 1/30

8:00 am-10:46 am

Nonstop4h 46m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

mar. 1/13

12:35 pm-11:14 pm

1 stop8h 39m

Chicago O'Hare Intl

vie. 1/23

1:20 pm-4:01 pm

Nonstop4h 41m

$183

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 Seattle to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Seattle 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 Seattle to Illinois

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 $116). Flying from Seattle to Illinois in July is currently the most expensive (average of $169). 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 diciembre 8, 2025.

It’s typically best to fly out from Seattle to Illinois in the afternoon. Doing so could potentially save you 19% on the flight price compared to flying in the morning, which is usually more expensive.

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 December 16, 2024.

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

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 diciembre 8, 2025.

The most flights from SEA to USIL are scheduled on a Friday (55 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (28 on average).

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 diciembre 8, 2025.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Alaska Airlines, Delta, and Hawaiian Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Alaska Airlines
8.0
Very good
11,419 reviews
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Delta
7.9
Good
8,011 reviews
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Hawaiian Airlines
7.8
Good
2,818 reviews
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
United Airlines
7.4
Good
9,089 reviews
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
American Airlines
7.2
Good
11,045 reviews
Alaska Airlines
8.0
Very good
11,419 reviews

Entertainment

7.0

Comfort

7.8

Boarding

8.1

Crew

8.5

Food

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.

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.

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

    Most people fly from Seattle/Tacoma Intl (SEA) if they book a flight from Seattle to Illinois. Seattle/Tacoma Intl is conveniently located just 11.4 mi from Seattle’s city center.

  • How long is the flight from Seattle to Illinois?

    Airlines like Alaska Airlines, United Airlines, and Southwest fly from Seattle to Illinois in about 3h 55m. The time it takes to get you to your destination is usually consistent. The distance between Seattle and Illinois is about 1728 mi. Most flights are nonstop.

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

    The cheapest airlines for a one-way flight from Seattle to Illinois are Frontier ($69), Spirit Airlines ($81), and Southwest ($84).

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

    The most popular flight routes from Seattle to Illinois are Seattle/Tacoma Intl - Chicago O'Hare Intl, Seattle/Tacoma Intl - Chicago Midway and Seattle/Tacoma Intl - Lambert-St Louis.

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

    No one likes to see their flight delayed. When booking a flight from Seattle to Illinois consider choosing WestJet (100%), Austrian Airlines (95%) or Royal Jordanian (92%) as they are the most reliable in getting you off to your destination on time.

  • What are the cheapest flights from Seattle to Illinois?

    On average you can expect to pay $849 for a flight from Seattle to Illinois. The cheapest flight overall is $98 while the most popular route, (Seattle/Tacoma Intl - Chicago O'Hare Intl) is currently priced at $140.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Seattle to Illinois 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 Seattle to Illinois?

    Currently, February is the cheapest month in which you can book a flight from Seattle to Illinois (average of $116). Flying from Seattle to Illinois in July is currently the most expensive (average of $169). 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

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Alternative routes for Seattle to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 8 airlines flying from Seattle to Illinois

Discover the top 8 airlines that operate flights from Seattle to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated diciembre 8, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$107Average$189FlexibilityNo cancel feeOn-time65%
Hawaiian AirlinesCheapest$121Average$288FlexibilityNo cancel feeOn-time85%
DeltaCheapest$122Average$294FlexibilityNo cancel feeOn-timeN/A
FrontierCheapest$137Average$273FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$164Average$424FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$174Average$477FlexibilityNo cancel feeOn-time75%
American AirlinesCheapest$184Average$441FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$184Average$361FlexibilityNo cancel feeOn-time63%

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