$147 Find Cheap Flights from Seattle to Illinois

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Seattle to Illinois departing on 9/9. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Illinois

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
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Flight Deals

Cheap Flights from Seattle to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicago1 stop$354
Moline
Moline1 stop$274
Peoria
Peoria1 stop$271
Bloomington
Bloomington1 stop$343
Champaign
Champaign1 stop$338
Springfield
Springfield1 stop$493
St. Louis
St. Louis1 stop$374
Decatur
Decatur1 stop$406
Paducah
Paducah1 stop$438
Chicago
Chicago1 stop$354
Moline
Moline1 stop$274
Peoria
Peoria1 stop$271
Bloomington
Bloomington1 stop$343
Champaign
Champaign1 stop$338
Springfield
Springfield1 stop$493
St. Louis
St. Louis1 stop$374
Decatur
Decatur1 stop$406
Paducah
Paducah1 stop$438

Book Cheap Seattle to Illinois Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle to Illinois that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Seattle to Illinois

Wed, Aug 12 - Sat, Aug 22
American Airlines Logo
3:35 pm - 11:59 pm
SEA
-
PIA
6h 24m
1 stop
American Airlines Logo
6:47 pm - 12:13 am
PIA
-
SEA
7h 26m
1 stop
$271American Airlines
Wed, Aug 26 - Sun, Aug 30
Multiple Airlines Logo
8:13 pm - 12:16 pm
SEA
-
MLI
14h 03m
1 stop
Multiple Airlines Logo
1:06 pm - 10:35 am
MLI
-
SEA
23h 29m
1 stop
$274Multiple Airlines
Fri, Sep 11 - Sun, Sep 13
Southwest Logo
7:00 am - 5:10 pm
SEA
-
MDW
8h 10m
2 stops
Southwest Logo
2:35 pm - 5:00 pm
MDW
-
SEA
4h 25mnonstop
$354Southwest
Thu, Jul 2 - Fri, Jul 17
Alaska Airlines Logo
1:10 pm - 7:21 pm
SEA
-
ORD
4h 11mnonstop
Alaska Airlines Logo
8:20 pm - 11:04 pm
ORD
-
SEA
4h 44mnonstop
$355Alaska Airlines
Thu, Aug 6 - Wed, Aug 12
Southwest Logo
7:25 pm - 5:40 am
SEA
-
MDW
8h 15m
1 stop
Southwest Logo
11:10 am - 6:10 pm
MDW
-
SEA
9h 00m
2 stops
$355Southwest
Wed, Jul 29 - Tue, Aug 4
Alaska Airlines Logo
5:48 pm - 11:59 pm
SEA
-
ORD
4h 11mnonstop
Alaska Airlines Logo
8:20 pm - 11:04 pm
ORD
-
SEA
4h 44mnonstop
$359Alaska Airlines
Wed, Aug 26 - Sat, Aug 29
United Airlines Logo
11:00 pm - 10:06 am
SEA
-
PIA
9h 06m
1 stop
United Airlines Logo
3:35 pm - 10:43 pm
PIA
-
SEA
9h 08m
1 stop
$371United Airlines
Thu, Aug 27 - Sun, Aug 30
Delta Logo
11:59 pm - 10:25 am
SEA
-
MLI
8h 26m
1 stop
Delta Logo
5:09 pm - 11:57 pm
MLI
-
SEA
8h 48m
1 stop
$371Delta
Fri, Sep 11 - Wed, Sep 16
United Airlines Logo
11:00 pm - 10:12 am
SEA
-
STL
9h 12m
1 stop
United Airlines Logo
12:59 pm - 7:15 pm
STL
-
SEA
8h 16m
1 stop
$374United Airlines
Fri, Aug 14 - Mon, Aug 24
Delta Logo
11:59 pm - 10:25 am
SEA
-
MLI
8h 26m
1 stop
Delta Logo
5:09 pm - 11:57 pm
MLI
-
SEA
8h 48m
1 stop
$384Delta
Booking Insights

KAYAK's insights & trends for Seattle to Illinois flights

Get data-powered insights and trends into flights from Seattle to Illinois to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from Seattle to Illinois?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Seattle to Illinois departing in August.

What is the cheapest Seattle to Illinois flight route?

Data is based on round-trip flight searches on KAYAK over the past month.

The cheapest ticket to Illinois from Seattle found in the last 5 days was to Chicago, at $332 round-trip. The most popular route is from Seattle (SEA) to Chicago O'Hare Intl Airport (ORD), and the cheapest round-trip airline ticket found on this route in the last 5 days was $332.

What is the cheapest time of day to fly to Illinois?

The average price for all round-trip flights from Seattle to Illinois depending on the time of departure, clicked by users on KAYAK in the last 2 weeks.

The cheapest time of day to fly to Illinois is generally in the evening, when round-trip flights cost $352 on average. Morning departures are around 28% more expensive than evening flights, on average. The most expensive time of day to fly to Illinois is generally in the morning, which is peak travel time and where the average cost of a ticket is $453.

Can I save money by flying with a layover from Seattle to Illinois?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of $376, prices are generally cheapest when you fly direct.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Seattle to Illinois is January, when tickets cost $47 (return) on average. On the other hand, the most expensive months are March and December, when the average cost of round-trip tickets is $686 and $510 respectively.

What’s the cheapest day of the week to fly from Seattle to Illinois?

The average price of all round-trip flights from Seattle to Illinois clicked on KAYAK for each day over the last 12 months.

For Seattle to Illinois, Wednesday is the cheapest day to fly on average and Sunday is the most expensive. Flying from Illinois back to Seattle, the best deals are generally found on Friday, with Monday being the most expensive.

How far in advance should I book a flight from Seattle to Illinois?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Seattle to Illinois, you should book around 3 weeks before departure, which saves you about 42% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 10 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$147
Best time to beat the crowds with an average 13% drop in price.
Most popular time to fly with an average 12% increase in price.
Flight from Seattle to St. Louis

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Seattle to Illinois?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Seattle to Illinois.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Seattle to Illinois?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Seattle to Illinois is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Seattle to Illinois?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly from Seattle to Illinois with an airline and back with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Seattle to Illinois?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying from Seattle to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Seattle to the following destinations at these prices or less: Chicago $205 one-way - $378 round-trip

Reviews of the top 5 airlines serving from Seattle to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Seattle to Illinois. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Seattle to Illinois? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
7.9
Alaska AirlinesOverall score based on 12509 reviews
7.0Food
8.1Boarding
7.0Entertainment
7.8Comfort
8.5Crew
Airline reviews

People were friendly. Flight was a little delayed. Maybe I missed the reason for it. Overall a nice experience.

8.0 ExcellentScott, Jun 2026
SEA - LAX
Read more Alaska Airlines reviews

People were friendly. Flight was a little delayed. Maybe I missed the reason for it. Overall a nice experience.

Crews were friendly enough. To help the airline I checked my carry on baggage. Typical "gonna be a full flight we need 19 carry on bags to be checked to help out". So I helped out only to have to wait 30+ mins for my luggage and risked not getting to my car rental on time. The return flight was delayed. Kept hearing employees say something about "they didn't have any power" which is kind of concerning. The air flow and air conditioning was insufficient. It was warm and stuffy during the flight. Plus no free wi-fi......Booooooo!

Didn’t even get on, check my flight to Seattle for details. Do better Alaska.

A five hour nonstop flight traveling over a few time zones and over the dinner hour and you get a small bag of pretzels. And no screens to watch movies. I

The flight kept getting delayed due to a maintenance issue. That happens, but there is no excuse for changing the gate FIVE TIMES, including one time nearly all the way across SeaTac. After we were delayed for 3+ hours, they did send us (via email) a $12 meal voucher...except you can't find a $12 meal anywhere in that airport, unless you consider a bag of M&M's and a bottle of water a meal. The plane had one problem after another but finally took off 4.5 hours late. This caused us to miss our hotel shuttle at ORD (they didn't run past midnight and it was 3 am) so we had to wait 25 minutes and pay for an Uber. I did get a $50 flight voucher from Alaska...big deal. Barely covers my Uber ride that I shouldn't have needed.

I upgraded to a better seat and it was much more comfortable. Nobody serves food anymore and actually on a 2+ hr flight not necessary. I didn’t even get water.

Check in & bag drop was straightforward. Alaskair changed the gate approx 40 min before departure, and I only became aware due to Google wallet update to my boarding pass. Had to move from gate N1 to C9 which required use of the Train, luckily I had time available.

Super impressed by staff courtesy, and assistance, Flight was one of the best I've had despite turbulence... Will definitely be flying Alaskan air as my preferred choice

My boarding passes were pulled from my Apple wallet and my 3 family members who were all sitting together in the same row all got put middle seats and were one of the last to board and barely were able to get our bags in the luggage bins.

Was disappointed not to have known Alaska Air offers no music, no flight aware, no films.

Flight was delayed over 3 hours. Planes were dirty. Staff indifferent. And they serve vegan pretzels as snacks.

It was great. The gate staff were very helpful in Portland when my son forgot his rolling bag and had to go back to get it just in time to make it on the plane. We really appreciate that. Great job!

Airline is not very senior friendly. Flights are late, forcing us to run to the connecting flight. Food is awful. Wish they would go back to pretzels and peanuts. During flight, pressurization isn’t quite right and all of our ears get plugged. Everything is nickel and dime, charging for boarding, seat selection and legroom. While a screen at the desk in the gate area says check your roll on bag now for free due to space limitation, the employee at the desk will not check the bag without a $100 fee. Insane.

Kayak could’ve posted the correct gate number. Almost missed my flight.

Slow boarding, limited food and drink portions. Bad delays and turbulence

there were two flight attendants that were up front...that were the best! They get KUDOs for making my trip only fantastic. Tell them Jeff said that!

OKay. I sat in the back of the plane and it was really loud between babies and little kids, and adults who.like to talk a lot and loudly most of the flight.

Flight coming out of Buffalo was delayed, so we had to be rescheduled on another flight from Baltimore to Phoenix which means we had a long layover and got home 3.5 hours late. Shuttle to parking stopped at 10pm, so we had to pay for an Uber to the parking lot and got charged an extra day of parking since it was after midnight. Not the best experience. Long day!

Was fine, delayed and feels like southwest is always late

I don't know why flying out of Sarasota requires two plane changes.

I have Precheck. Flew HPN to DEN and return this past weekend. Delta didn't attach my Precheck number to this trip. So it was waiting in general line especially in Denver. Unavailable.

Original flight was delayed, then cancelled and the gate staff did not expedite rebooking. Also, no instructions were given that a ticket number was needed before being called to facilitate rebooking. This could have been much more organized.

Be on time? When not on time a circling for over an hour offer more than 1 bag of chips to the passengers? It was a 7 hour flight by the time we got done.

The Boarding process was great. Particularly since my wife and I require assistance. The flight attendants were amazing. We travel frequently; they honestly were a cut above. 😀

Crew was nice, meal was good. Entertainment had to be rebooted 3 times and still did not work. Turns out there was residue on screen, it needed to be cleaned to prevent the touchscreen buttons from continuously activating. I had entertainment for the last 45 minutes of a 5 hour 45 minute flight. Really unacceptable for first class. Flight attendent indicated your cleaning solution creates this problem. Seems as if this is widely known, you should be using a different product or cleaning better. Really really disappointing which simply added to the wi fi on your planes with reliably never ever works.

Snacks and included beverages were appreciated. Boarding went smoothly. Plenty of overhead bin space. Seats get very uncomfortable after a couple of hours. After waiting 10 painful minutes for my walker, a very nice Delta guest agent pushed me in a wheelchair to the gate. It was finally delivered to me after another 15 minutes . Our checked bag was on the carousel long b4 I was able to retrieve it. Fortunately it was still there but somewhere along the way the straps we used to secure it were removed and and were not reattached. Wish I had made note of the agents name.

It was fine. 55 minute flight. No snacks or beverage service offered. Boarding went smoothly and my walker was waiting for me on the jet way.

The cabin temperature was nice and cool. The wifi was not working.

Could not get my connecting flight boarding pass until four hrs before departure! Ver annoying especially since the staff could not explain why!

There was an unruly family behind us that made the short flight miserable!!! The cabin crew did nothing to contain it.

Our flight was delayed several Times due to mechanical issues. Although I understand this may happen at times, it was very inconvenient and we had to book a hotel for an overnight stay. We were traveling with my 3-yo grandson and waiting at the airport from noon until 6:30pm with no reassurance that our next rescheduled flight would depart, we had to decide what’s best for him. A day later, I found out that I may be able to demand compensation if my flight is delayed more than 4 hours. I will hav to read the fine print next time.

Over 5 hour delay with minimal updates or ability to standby for alternative flights. During boarding and 1 hr+ wait for takeoff, seats were drenched w water from air conditioning condensation and always leftover crumbs on carpet and seats

Boarded early, left early, arrived 40 mins early! A win win for me!

These airplanes should be illegal. The seats are two tight, it is a safety issue. Wheelchair support was ridiculously slow. We almost missed our flight.

This flight is a quick way to get to Chicago, but a bit expensive.

Very comfortable seating and the Flight staff were very attentive. The premium economy section that I was seated in was very clean, updated, and well appointed. I would highly recommend flying United Airlines as this experience was better than the Japan Airlines business class that I flew several months ago.

O’hsre taxi and deboarding took 40 minutes. Needed 20 minutes extra time between connecting flights to avoid running through terminal.

Standard flight with a drinks and a snack- overall very quick flight. The flight attendants were very strict, bordered on rude.

Delayed - weather wasn't bad at either end. Also sat on tarmac in ORD.

boarded early to only find out that flight would sit at gate for 45 min to an hour. Landed in chicago and sat on runway for over an hour before got to gate. Total delay was extensive for a 45 min flight door to door.

The flight was delayed significantly and we sat on runway after landing for awhile. Best thing was the flight attendant, Jenny, in first class, who was very professional and attentive. She was excellent - the rest of the flight was not.

The flight attendants were extremely sourly and borderline rude. I did not feel appreciated as an AA customer once.

The flight from LA to Chicago was smooth and service was very good overall.

The Mario was so helpful and provided amazing customer service however l have being waiting for a callback for almost a week now and have not heard anything further after l informed them l wanted to change my date of traveling because of my hospital appointment even send them proof and l was unable to use manag your booking on their website is a bit frustrating and l would appreciate an update on My request as soon as possible. And have called them times without numbers no response

Awful, tons of delays, I got into Chicago multiple hours late meaning I hit the very traffic I tried so desperately to avoid. Just empty apologies from American Airlines text alerts. Trash behavior from a trash airline.

They lost my baggage and I am still struggling to the information and update

Requested early boarding to disinfect seat, tray table, etc. before general boarding. Instructed to board after wheelchair passengers. Waited on jet bridge behind 12 wheelchair passengers. Stopped immediately after entering plane to wait for gate agent in rear of plane cleaning a seat that was wet, got to my row and found both seats adjacent to mine already occupied, with the lack of room making it impossible for me to clean my own space and defeating the purpose of my boarding early. Cleaned the armrests and tray table as best I could.

The wifi experience is awful. I had to try again and again, taking over 30 minutes, to connect to the wifi. I had to watch the same two ads over and over until I was finally successful. Once connected, it was anything but "high speed" and disconnected at least three times during the flight.

It was good, the staff was great, and the food, was as usual, tea and biscuit. Bathroom was clean, and the plane was clean as well.

Very good I can’t complain one bit. Thank you American Airlines for making my flight enjoyable and safe!

Everything you need to know for your flight from Seattle to Illinois

Information on your arrival and departure airports