$63 Find Cheap Flights from Seattle to Boulder

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 Boulder departing on 5/1. 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

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Everything you should know

Cheapest round-trip
$92
Typical prices: $302-$156
Frontier
Tue 4/14Tue 4/21
SEA - DEN • Non-stop
Cheapest one-way
$63
Typical prices: $98-$203
Frontier
Fri 5/1
SEA - DEN • Non-stop
Arrival airport
You can't fly directly to Boulder. It is served by Denver (DEN), located 33.4 miles from Boulder.
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Flight Deals
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Flight Deals

Cheap Flights from Seattle to Boulder (SEA-DEN)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle to Boulder 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 Boulder

Tue, Apr 14 - Tue, Apr 21
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$92Frontier
Wed, Apr 15 - Tue, Apr 21
Frontier Logo
8:07 pm - 11:59 pm
SEA
-
DEN
2h 52mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$93Frontier
Tue, Apr 21 - Tue, Apr 28
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$97Frontier
Tue, Apr 21 - Wed, Apr 22
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$98Frontier
Tue, Apr 28 - Tue, May 5
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:20 am - 6:35 pm
DEN
-
SEA
12h 15m
1 stop
$101Frontier
Wed, Apr 15 - Sat, Apr 25
Frontier Logo
8:07 pm - 11:59 pm
SEA
-
DEN
2h 52mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$102Frontier
Sat, Apr 25 - Wed, Apr 29
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$103Frontier
Wed, Apr 15 - Wed, Apr 29
Frontier Logo
8:07 pm - 11:59 pm
SEA
-
DEN
2h 52mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$106Frontier
Sat, May 2 - Wed, May 6
Frontier Logo
7:12 pm - 10:59 pm
SEA
-
DEN
2h 47mnonstop
Frontier Logo
7:50 am - 9:49 am
DEN
-
SEA
2h 59mnonstop
$107Frontier
Mon, Apr 20 - Sat, May 2
Frontier Logo
4:20 pm - 8:11 pm
SEA
-
DEN
2h 51mnonstop
Frontier Logo
7:15 am - 9:27 am
DEN
-
SEA
3h 12mnonstop
$108Frontier
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$63
Best time to beat the crowds with an average 26% drop in price.
Most popular time to fly with an average 6% increase in price.
Flight from Seattle to Denver

When to book flights from Seattle to Boulder

Are your dates flexible? Find out the best times to travel from Seattle to Boulder based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price

Flights from Seattle to Boulder: the best tips from KAYAK users' own experiences

Insights shared by verified travelers who flew the route from Seattle to Boulder 
DebraFlew with Alaska Airlines
SEA
-
DEN
Feb 2026
Seattle TSA much improved. Faster service. Baggage check-in ok. I'm sure will get faster as people get used to it.
Verified travelerFlew with Alaska Airlines
SEA
-
DEN
Mar 2025
Alaska Air is very efficient & on-time so allow enough time to get luggage, go thru Customs & Immigration, & long security lines. Terminals in SEA are readily accessible by trains but more signage is needed. Fortunately, Information booths are everywhere & are manned by very helpful staff.
MichaelFlew with Delta
SEA
-
DEN
Apr 2025
Train from Denver airport to downtown is easy to use.
Verified travelerFlew with Alaska Airlines
SEA
-
DEN
May 2024
When flying from Seattle to Denver, be ready to take our any electronics and put them in separate bins when going through security. You will also most likely have to take off your jacket as well. During our flight back the flight randomly changed so be on the lookout in case that happens to you! It was by chance that I checked my ticket and saw that the gate changed last minute.

FAQs for booking flights from Seattle to Boulder

  • Which airports will I be using when flying from Seattle to Boulder?

    When flying out of Seattle you’ll be using Seattle/Tacoma Intl. Boulder does not have its own airport so you’ll be flying into nearby Denver Intl airport, which is 33.4 mi away.

  • How long does a flight from Seattle to Boulder take?

    Direct flights cover the 1,022 miles separating Seattle and Boulder in about 2h 35m.

  • How many flights are there between Seattle and Boulder?

    47 direct flights run between Seattle and Boulder on a daily basis. On average, there are about 331 departures each week.

  • What’s the cheapest day of the week to fly between Seattle and Boulder?

    Consider leaving on a Thursday and avoid Saturdays if you are looking for the best rates. For your return to Seattle, you’ll find the best rates on Fridays and the most expensive ones on Saturdays.

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

    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 Boulder.

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

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Boulder from Seattle 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 Boulder?

    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 to Boulder with an airline and back to Seattle with another airline.

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

    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 to Boulder from Seattle up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • Which airlines provide the cheapest flights from Seattle to Boulder?

    In the last 72 hours, the cheapest one-way ticket between Seattle and Boulder found on KAYAK was with Frontier for $29. Frontier offered a round-trip connection from $57 and Hawaiian Airlines from $78.

Top tips for finding cheap flights from Seattle to Boulder

  • There is no airport in Boulder. Instead, you’ll be flying into Denver Airport when flying between Seattle and Boulder.
  • The cheapest flight from Seattle to Boulder was found 66 days before departure, on average.
  • Book at least 1 week before departure in order to get a below-average price.
  • High season is considered to be May, June and July. The cheapest month to fly is January.

Reviews of the top 5 airlines serving Seattle to Boulder

 
Need help choosing which airline to fly with from Seattle to Boulder? 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.
8.0
SouthwestOverall score based on 4343 reviews
8.0Comfort
8.6Crew
7.0Food
7.5Entertainment
8.1Boarding
Airline reviews

The Air hostess were very rude on my flight from Houston to Austin . Their regular communication itself felt a they are shouting at people.

4.0 Okaysangeetha, Apr 2026
AUS - SJC
Read more Southwest reviews

The Air hostess were very rude on my flight from Houston to Austin . Their regular communication itself felt a they are shouting at people.

Communication about the delayed flight was poor. We were told to move gates three times but that was bad information. We went from gate 128 to gate 126 and then to gate 123 and back to gate 126. Communication about the delay was bad. Ended up being 1 1/2 hour late getting home.

Plane was late. Zero service for 2+ hour flight and it was not that bumpy.

It was good from LAX to Phoenix, But the connection in Phoenix to Tulsa was not that great. The staff on both flights were great. The choice of free entertainment was ok nothing to brag about. The 45 min delay because of some electrical issue wasn't great from Phoenix to Tulsa. We sat there with hardly any air, The seat I had was between windows so the side of the plane pushed in on you. My being a bigger man it then made the seating area uncomfortable. The seats on the plane had no power to connect to recharge your phone or anything. I would recommend that they should look into a slot or clamp to hold your phone to enjoy while watching the entertainment choices hands-free. Also make it possible to raise the inner seat by the window be able to raise the arm rest up to make more room for larger people to set more comfortably. I would also say other then that stop price gouging the airfare or nickel and diming everything. Not fair for people having to fly for emergencies and be paying for higher prices due to the season or holidays. Your making your money either way and the cost of flying is still going to be the same regardless if there's 100 people or 200 people.

Had a great flight. Delayed takeoff, but comfortable. Snacks were good.

Love them will get a Southwest card to track my points and keep flying with them. My family and I were pleased with the services.

I have roller bag with food and medication told me I couldn't bring on my 2nd flight today. 15 years flying with SW never an issue with that bag.

Southwest continues to do less for more money. Flight attendants used to be fun and friendly. But now it’s like they don’t even see you. Such a shame.

Great flight. Good snacks and drinks. Grateful it was free. The flight from Nashville to louisville, i think her name was Tracy (not sure that's right) super awesome, nice and cheerful. She really enjoyed being at work today! She was the person who scanned the boarding pass on flight wn941. She should be recommended for a raise !

I liked it better when you were truer to your roots Am paying more for less fun

We never had an experience on Alaska Airlines. We missed our flight .

Flight was on time departure & arrival. Staff was efficient & attentive. Food was better than normal. Wish they had some sort of entertainment screens loke Delta. I would fly Alaska again though.

It was a bumpy flight but the crew was very attentive and made it a safe and enjoyable experience.

Very easy, stress free airline. Was a wonderful experience. Will use again

The final trip home wasn’t as bad as the trip there. Even with the paid upgrade the comfort level was mediocre at best.

I paid $129 to be upgraded to better seat only ti be completely ignored by flight attendants I think because I used the front restroom ???? I was dozing off and on but I was never once offered a beverage or snack but my seat mates were served numerous double vodkas. I want my money back. I tried to call Alaska Airlines complaints phone number and was told it was 2.5 hours to hold.

Don’t fly with Alaska if you have a layover in Seattle. Guaranteed to screw you over. We waited at terminal S3 &were >2 hours delayed(mechanical issues)and told to change terminals to a different plane that required riding 3 shuttles to get to new terminal N14. Then they delayed the flight even further and changed gates again. when I went to the customer service in terminal N, the manager turned me away without apologizing & refused to assist me but mandated I leave her alone as her shift is nearly finished and insisted I totake another 2 shuttles to terminal C so I can just talk to another service rep while dragging my family of 4/ kids in tow.

i canceled my flight from SEA to SFO, SNA to SEA and received full refund from Alaska Airlines. i am pleased with the customer service.

Departing flight for our weekend trip was cancelled due to weather which meant our return flight was useless. The whole thing was difficult to get support through but Alaska did recover and was able to reimburse us for the flights yesterday. For some reason, Kayak was not kept in the loop, adding to the confusion.

i canceled my return flight package with Alaska Airlines. Customer Service was excellent and assisted me to cancelled both of our reservations and returned the payment in full. that is excellent service and understanding and empathy of the customers' needs. i like Alaska Airlines and recommend AS to everyone.

We departed and landed early which was a nice surprise. The boarding process was slow.

N Everything was perfect from boarding to assistance to baggage in Tampa

Subpar. The seating on the plane is almost unbearable. We are literally touching and/or sitting on each other which is totally unacceptable and shameful. Pilots and crew was very accommodating and friendly.

The boarding was organized and informative but the plane was tight meaning that you were sitting on one another and extremely uncomfortable. It’s disappointing that can’t have common seating comfort on the plane.

Loved the crew! Sucks that we went from 1 hour and 8 minute layover to a 3 hour layover. But weather sucks like that.

I was told that they needed to check my bag at the gate and to pick it up at the gate in Richmond. No big deal. I know they can't control the weather, but we flew around RIC for 45 minutes to avoid the storm and were 25 minutes late leaving as well. Once we landed, we were told to go to baggage claim to pick up our luggage. I went to bathroom, paid for parking, and went to the assigned baggage claim location. United flight people came down with us as well. They got their luggage immediately. Next, South West people came down about 10 minutes later. They got their luggage next. We finally got our luggage around 30 minutes in waiting. Was not a wonderful experience. No reflection on Delta, but the ground crew was lousy at best.

Everything could have benn better. Short fly, no food, no entertainment and no wifi.

Flight delayed. Air broken. Cabin was hot enough to pass out. Delta shuttle’s becoming worse and worse.

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.

I had a cancelled flight because of technical issues going to my destination, and a delayed flight coming home. All told it wasn’t a total bust.

During landing. 2 crew members passed 3 times by my lane and didn't notice that people in front of us had their site to the furthermore reclined... That was uncomfortable and could have been dangerous.

Seats are uncomfortable. This has been a trend in the industry for decades. Trying to fit more seats on each plane to increase profits at the expense of the passenger.

It’s always a great time flying with united airlines.

We got delayed three hours and nobody thought to have the bathroom fixed while we were sitting waiting to board? took a full hour to have maintenance come and check it off. Had to shut the bathroom down twice so that the pilots could go to the bathroom. Everyone missed their connections.

Women boarding passengers at the gate was absolutely rude and disrespectful of passengers. The flight attendant was absolutely delightful! Smiling and connected with the passengers. So happy. The seats are cramped and uncomfortable but I guess that’s just the way it is Communication regarding flight was excellent

As great a red-eye flight as red-eye flights can be.

Both of my flights arrived early and check in process was smooth

Everything was on time Will use united again for sure

The flight was delayed by two de-icings. The seatbelt did not work correctly. It did not stay tight.

It was an early flight and most people napped/slept and the crew let us which was nice.

More inflight connection. And leg space is horrible. And the paying for baggage I'd ridiculous!!!

It was costly and difficult to check in. $85 to take a small suitcase with me, carry on or checked and $75 on the return trip, Plus $25 if I didn't check my self in check in $25, because I couldn't do it on the kiosk. Small very uncomfortable seats, waited on the runway for near an hour each way. It was my worst flight to date.

Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.

The experience was good. No frills but I got there safe and sound and on time.

As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.

The ticketing agents were rude but then we had a great gate agent very nice we had to ride a buss out to where the plane was parked but it was in some back corner of the airport when we got to the plane the captain who was great btw was cleaning the plane because the same rude ticketing agent told them they we not contracted to vacuum the plane. The ride to las Vegas was fine We had a connecting flight to Dallas. The flight was fine but when we arrived in Dallas everyone who flew on any frontier airlines the picked up bags from baggage claim D15 had to wait over a hour for their bags to start we arrived at 11:30pm ish to the gate we didn't leave the baggage clamed till 12:50 am very not happy and i used to fly frontier 4 times a week for work in Denver i will not be using them again

Frontier Airlines was AWFUL. I was an hour early for my flight and the lady refused to check me in. I had to purchase a whole new ticket with a different airline.

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

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