What is the cheapest airline that flies from Illinois to Seattle/Tacoma Intl?

Frontier, United Airlines, and Southwest are the most popular carriers operating from Illinois to Seattle/Tacoma Intl

How many flights depart from Illinois to Seattle on average per week?

As of August 2025, there are 375 flights per week flying from Illinois to Seattle. The most common day of the week flights depart is Mon, with 26% of flights taking off on this day.

What airlines fly to Seattle?

Alaska Airlines, Delta and American Airlines are the top three most popular airlines that fly to Seattle from Illinois according to our data. Alaska Airlines is the first choice among our users, with 33% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 8 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

How long does it take to fly to Seattle?

Flight times vary depending on what airport in Illinois you fly out of and what airport in Seattle you fly into. For example, flying from Chicago to Seattle takes 4h 30m on average. On the other hand, flying from Peoria to Seattle takes 6h 34m on average. Keep in mind that it’s always quicker to opt for a non-stop flight, so be sure to check momondo if there are any available for your route.

How many flights depart from Illinois to Seattle on average per day?

53 flights are operational daily from Illinois to Seattle as of August 2025. The most popular departure time for this route is 8:00PM, with 33% of flights per day taking off at noon.

When did momondo last update prices for flights from Illinois to Seattle/Tacoma Intl Airport?

Prices for flights from Illinois to Seattle/Tacoma Intl Airport refresh daily.

How many operators does momondo search for flights from Illinois to Seattle/Tacoma Intl Airport?

As of August 2025, there are 8 operators available to choose from for flights from Illinois to Seattle/Tacoma Intl Airport.

How old do you have to be to fly from Illinois to Seattle/Tacoma Intl Airport?

Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Illinois to Seattle/Tacoma Intl Airport.

What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?

The required travel and health documents for your Seattle/Tacoma Intl Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Seattle/Tacoma Intl Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

$74 Cheap Flights from Illinois to Seattle in 2025

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Find the cheapest flights from Illinois to Seattle

Round-trip

One-way

Last minute

Direct

Cheap round-trip flights

7:55 pm - 12:30 amSTL-SEA

6h 35m1 stop

6:12 am - 9:06 amSEA-STL

24h 54m1 stop

$147Frontier

Find Deal

Thu, Sep 11 - Mon, Sep 15

5:35 am - 12:30 amORD-SEA

20h 55m1 stop

6:12 am - 11:59 pmSEA-ORD

15h 47m1 stop

$152Frontier

Find Deal

Thu, Oct 2 - Mon, Oct 6

5:49 pm - 10:59 pmSTL-SEA

7h 10m1 stop

7:00 am - 3:44 pmSEA-STL

6h 44m1 stop

$168United Airlines

Find Deal

Sat, Sep 20 - Sat, Oct 4

11:10 am - 1:30 pmSTL-SEA

4h 20mnonstop

9:10 pm - 9:35 amSEA-STL

10h 25m1 stop

$173Southwest

Find Deal

Sun, Sep 21 - Tue, Sep 23

7:05 am - 12:07 pmORD-SEA

7h 02m1 stop

12:20 am - 6:22 amSEA-ORD

4h 02mnonstop

$176

Find Deal

Sat, Oct 25 - Thu, Oct 30

6:20 am - 8:50 amORD-SEA

4h 30mnonstop

5:55 pm - 12:03 amSEA-ORD

4h 08mnonstop

$177Hawaiian Airlines

Find Deal

Sun, Aug 31 - Sat, Sep 6

11:10 am - 1:30 pmSTL-SEA

4h 20mnonstop

6:45 am - 5:40 pmSEA-STL

8h 55m2 stops

$178Southwest

Find Deal

Sun, Sep 21 - Tue, Sep 23

6:20 am - 8:50 amORD-SEA

4h 30mnonstop

12:59 am - 7:03 amSEA-ORD

4h 04mnonstop

$178Hawaiian Airlines

Find Deal

Sun, Aug 31 - Fri, Sep 5

7:15 am - 12:07 pmORD-SEA

6h 52m1 stop

5:50 pm - 11:59 pmSEA-ORD

4h 09mnonstop

$181

Find Deal

Wed, Oct 15 - Sat, Oct 18

5:49 pm - 10:59 pmSTL-SEA

7h 10m1 stop

8:45 am - 4:33 pmSEA-STL

5h 48m1 stop

$192United Airlines

Find Deal

Sat, Sep 13 - Sat, Sep 20

Frontier flights from Illinois to Seattle

Our best Frontier deals on Illinois to Seattle flight tickets

Frontier

Sep 11

STL7:55 pmLambert-St Louis

6h 35m

1 stop

SEA12:30 amSeattle/Tacoma Intl

Sep 15

SEA6:12 amSeattle/Tacoma Intl

24h 54m

1 stop

STL9:06 amLambert-St Louis

$147

Find similar

Frontier

Oct 2

ORD5:35 amChicago O'Hare Intl

20h 55m

1 stop

SEA12:30 amSeattle/Tacoma Intl

Oct 6

SEA6:12 amSeattle/Tacoma Intl

15h 47m

1 stop

ORD11:59 pmChicago O'Hare Intl

$152

Find similar

Frontier

Oct 15

ORD7:15 amChicago O'Hare Intl

6h 52m

1 stop

SEA12:07 pmSeattle/Tacoma Intl

Oct 25

SEA8:43 pmSeattle/Tacoma Intl

10h 53m

1 stop

ORD9:36 amChicago O'Hare Intl

$153

Find similar

United Airlines flights from Illinois to Seattle

Our best United Airlines deals on Illinois to Seattle flight tickets

United Airlines

Sep 20

STL5:49 pmLambert-St Louis

7h 10m

1 stop

SEA10:59 pmSeattle/Tacoma Intl

Oct 4

SEA7:00 amSeattle/Tacoma Intl

6h 44m

1 stop

STL3:44 pmLambert-St Louis

$168

Find similar

United Airlines

Sep 13

STL5:49 pmLambert-St Louis

7h 10m

1 stop

SEA10:59 pmSeattle/Tacoma Intl

Sep 20

SEA8:45 amSeattle/Tacoma Intl

5h 48m

1 stop

STL4:33 pmLambert-St Louis

$192

Find similar

United Airlines

Aug 31

STL6:35 amLambert-St Louis

11h 16m

2 stops

SEA3:51 pmSeattle/Tacoma Intl

Sep 10

SEA6:25 amSeattle/Tacoma Intl

12h 21m

2 stops

STL8:46 pmLambert-St Louis

$343

Find similar

Fly from

Fly to

Route

Depart

Return

Price

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Thu 9/11

7:55 pm-12:30 am

1 stop6h 35m

Seattle/Tacoma Intl

Mon 9/15

6:12 am-9:06 am

1 stop24h 54m

$147

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Thu 10/2

5:35 am-12:30 am

1 stop20h 55m

Seattle/Tacoma Intl

Mon 10/6

6:12 am-11:59 pm

1 stop15h 47m

$152

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 9/20

5:49 pm-10:59 pm

1 stop7h 10m

Seattle/Tacoma Intl

Sat 10/4

7:00 am-3:44 pm

1 stop6h 44m

$168

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sun 9/21

11:10 am-1:30 pm

Nonstop4h 20m

Seattle/Tacoma Intl

Tue 9/23

9:10 pm-9:35 am

1 stop10h 25m

$173

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Sat 10/25

7:05 am-12:07 pm

1 stop7h 02m

Seattle/Tacoma Intl

Thu 10/30

12:20 am-6:22 am

Nonstop4h 02m

$176

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Sun 8/31

6:20 am-8:50 am

Nonstop4h 30m

Seattle/Tacoma Intl

Sat 9/6

5:55 pm-12:03 am

Nonstop4h 08m

$177

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sun 9/21

11:10 am-1:30 pm

Nonstop4h 20m

Seattle/Tacoma Intl

Tue 9/23

6:45 am-5:40 pm

2 stops8h 55m

$178

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Sun 8/31

6:20 am-8:50 am

Nonstop4h 30m

Seattle/Tacoma Intl

Fri 9/5

12:59 am-7:03 am

Nonstop4h 04m

$178

ChicagoSeattle

ORD - SEA

ORDSEA

Chicago O'Hare Intl

Wed 10/15

7:15 am-12:07 pm

1 stop6h 52m

Seattle/Tacoma Intl

Sat 10/18

5:50 pm-11:59 pm

Nonstop4h 09m

$181

St. LouisSeattle

STL - SEA

STLSEA

Lambert-St Louis

Sat 9/13

5:49 pm-10:59 pm

1 stop7h 10m

Seattle/Tacoma Intl

Sat 9/20

8:45 am-4:33 pm

1 stop5h 48m

$192

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first

How to get the cheapest flight ticket from Illinois to Seattle

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

Prices

Airlines

Other information

What is the cheapest month to fly to Seattle?

In general, February is the cheapest month to fly from Illinois to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $214. If you don’t want to visit Seattle in February, then you should wait until April to fly from Illinois, when ticket prices are also cheap, with an average price of $229.

What is the cheapest day to depart on your flight to Seattle?

On average, the least expensive day to fly to Seattle from Illinois is on a Wednesday. momondo users have found tickets for Wednesday departures for as low as $329. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Monday is the most expensive day to depart from Illinois because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $447.

What is the cheapest time of day to depart on your flight to Seattle?

Flying to Seattle from Illinois in the evening is the least expensive time of day to depart. momondo users have found prices as low as $321 when looking at flights departing in the evening. Flights to Seattle are more costly in the morning, with an average ticket price of $376. Departure times in the morning fall within the peak daily travel times, which is why tickets can be more expensive.

What is the cheapest Illinois to Seattle/Tacoma Intl flight route?

Fly from Chicago Midway to Seattle/Tacoma Intl for the best Illinois - Seattle/Tacoma Intl flight prices

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

You are more likely to see cheaper flights to Seattle from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $281 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from Illinois for as low as $242 on momondo.

What cabin class options are available on Illinois to Seattle/Tacoma Intl flights?

There are 4 cabin classes available to choose from on Illinois to Seattle/Tacoma Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Illinois to Seattle flights?

You could potentially save up to 9% on your flight if you consider stops on a Illinois to Seattle flight.

Cheap Illinois to Seattle flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Illinois to Seattle

Best Price Found	$74
Fastest flight time	4h 19m
Direct flights	Every day
Airports in Seattle	1 airport

The best one-way flight to Seattle from Illinois in the past 72 hours is $74. The best round-trip flight deal from Illinois to Seattle found on momondo in the last 72 hours is $147.

The fastest flight from Illinois to Seattle takes 4h 19m

Direct flights go from Illinois to Seattle every day.

There is 1 airport near Seattle: Seattle/Tacoma Intl (SEA)

Search flight deals

When did momondo last update prices for flights from Illinois to Seattle/Tacoma Intl Airport?
Prices for flights from Illinois to Seattle/Tacoma Intl Airport refresh daily.
How many operators does momondo search for flights from Illinois to Seattle/Tacoma Intl Airport?
As of August 2025, there are 8 operators available to choose from for flights from Illinois to Seattle/Tacoma Intl Airport.
How old do you have to be to fly from Illinois to Seattle/Tacoma Intl Airport?
Although the minimum age for a child to fly alone is five, airlines that offer an unaccompanied minor (UMNR) service may have their own age limits, which could be impacted by factors such as flight length, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Illinois to Seattle/Tacoma Intl Airport.
What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?
The required travel and health documents for your Seattle/Tacoma Intl Airport trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Seattle/Tacoma Intl Airport. We recommend that you seek guidance from your airline or a reliable third party such as IATA.
What is the most popular plane model from Illinois to Seattle?
momondo data reveals that the most frequently booked plane model on the route from Illinois to Seattle is Boeing 737-900 Passenger/BBJ3 (winglets), representing 18.00% of all bookings. The subsequent popular models are Boeing 737-800 at 13.06%, Boeing 737-800 Passenger/BBJ2 (winglets) at 11.68%, and Airbus A321-100/200 at 10.49%.

Best airlines flying from Illinois to Seattle

Compare and see reviews for airlines that fly from Illinois to Seattle with momondo

Airline	Rating	Free Cancellation	Price
Hawaiian Airlines	PriceFrom $90	Free Cancellation	Rating 7.8 2,664 reviews	Search Hawaiian Airlines flights
Spirit Airlines	PriceFrom $98	Free Cancellation	Rating 6.3 8,038 reviews	Search Spirit Airlines flights
Frontier	PriceFrom $118	Free Cancellation	Rating 5.8 3,212 reviews	Search Frontier flights
Delta	PriceFrom $119	Free Cancellation	Rating 8.0 7,981 reviews	Search Delta flights
Alaska Airlines	PriceFrom $157	Free Cancellation	Rating 8.0 10,000 reviews	Search Alaska Airlines flights
United Airlines	PriceFrom $168	Free Cancellation	Rating 7.4 8,925 reviews	Search United Airlines flights
American Airlines	PriceFrom $169	Free Cancellation	Rating 7.2 10,000 reviews	Search American Airlines flights
Southwest	PriceFrom $194	Free Cancellation	Rating 8.0 4,246 reviews	Search Southwest flights

Leavenworth

Tacoma

SeaTac

Ocean Shores

Olympia

Renton

Kent

Lynnwood

Federal Way

Puyallup

Marysville

Tukwila

Kirkland

Lakewood

Centralia

Shoreline

Cle Elum

Fife

Westport

Redmond

Why use momondo?

Why should I use momondo to find a flight deal from Illinois to Seattle?

Finding the right flight to Seattle from Illinois is quick and easy when you have a range of options in front of you, from reputable agents and recognisable airlines. Options that can then be filtered down to find the best fit. That is what momondo does. We make finding flights to Seattle quick and easy, saving you time and money.

Can I find flights from Illinois to Seattle with flexible booking policies on momondo?

Yes. momondo enables you to select and highlight flights to Seattle from Illinois with this policy.

How can momondo help me find flights from Illinois to Seattle?

Once you have performed a search for Illinois to Seattle flights, momondo helps you find the right one by offering useful filters to narrow down your flight selection. Flights can be filtered by multiple factors such as airline, airport and price; but also by other criteria like aircraft type and payment method.

I’m not ready to book a flight from Illinois to Seattle right now. Can momondo alert me if prices change?

If you are not ready to book a flight from Illinois to Seattle now, use our insights above to find helpful tips or alternatively set up a price alert, where momondo will track prices on flights to Seattle and let you know when they change.

An easier way to manage your Seattle trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.

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Cheap flights from Illinois to Seattle from $74

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Illinois to Seattle departing on 9/26. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.

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Big names and deals

Filter for what you want

Filter for what you want

Trusted and free

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Find the cheapest flights from Illinois to Seattle

Cheap round-trip flights

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Cheap last minute flights

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Frontier flights from Illinois to Seattle

Our best Frontier deals on Illinois to Seattle flight tickets

United Airlines flights from Illinois to Seattle

Our best United Airlines deals on Illinois to Seattle flight tickets

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Use the filters below to find and compare flights from Illinois to Seattle that are best for you.

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How to get the cheapest flight ticket from Illinois to Seattle

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Seattle?

What is the cheapest day to depart on your flight to Seattle?

What is the cheapest time of day to depart on your flight to Seattle?

What is the cheapest Illinois to Seattle/Tacoma Intl flight route?

Fly from Chicago Midway to Seattle/Tacoma Intl for the best Illinois - Seattle/Tacoma Intl flight prices

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

What cabin class options are available on Illinois to Seattle/Tacoma Intl flights?

There are 4 cabin classes available to choose from on Illinois to Seattle/Tacoma Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Illinois to Seattle flights?

You could potentially save up to 9% on your flight if you consider stops on a Illinois to Seattle flight.

What is the cheapest airline that flies from Illinois to Seattle/Tacoma Intl?

Frontier, United Airlines, and Southwest are the most popular carriers operating from Illinois to Seattle/Tacoma Intl

What airlines fly to Seattle?

How many flights depart from Illinois to Seattle on average per day?

53 flights are operational daily from Illinois to Seattle as of August 2025. The most popular departure time for this route is 8:00PM, with 33% of flights per day taking off at noon.

How many flights depart from Illinois to Seattle on average per week?

As of August 2025, there are 375 flights per week flying from Illinois to Seattle. The most common day of the week flights depart is Mon, with 26% of flights taking off on this day.

How long does it take to fly to Seattle?

Cheap Illinois to Seattle flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Illinois to Seattle

Best Price Found

Fastest flight time

Direct flights

Airports in Seattle

When did momondo last update prices for flights from Illinois to Seattle/Tacoma Intl Airport?

How many operators does momondo search for flights from Illinois to Seattle/Tacoma Intl Airport?

How old do you have to be to fly from Illinois to Seattle/Tacoma Intl Airport?

What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?

What is the most popular plane model from Illinois to Seattle?

Best airlines flying from Illinois to Seattle

Compare and see reviews for airlines that fly from Illinois to Seattle with momondo

Traveling to a place near Seattle?

Why use momondo?

Why should I use momondo to find a flight deal from Illinois to Seattle?

Can I find flights from Illinois to Seattle with flexible booking policies on momondo?

How can momondo help me find flights from Illinois to Seattle?

I’m not ready to book a flight from Illinois to Seattle right now. Can momondo alert me if prices change?

An easier way to manage your Seattle trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.

Find better results for your trip to the United States

Airports servicing Washington