$38 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 10/11. 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.
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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, Oct 28 - Wed, Oct 29
Frontier Logo
6:00 am - 9:51 amSEA-DEN
2h 51mnonstop
Frontier Logo
8:55 pm - 11:02 pmDEN-SEA
3h 07mnonstop
$71Frontier
Find Deal
Sat, Sep 20 - Sat, Sep 27
Frontier Logo
7:00 am - 10:53 amSEA-DEN
2h 53mnonstop
Frontier Logo
6:33 pm - 8:39 pmDEN-SEA
3h 06mnonstop
$74Frontier
Find Deal
Tue, Sep 16 - Tue, Sep 23
Frontier Logo
7:00 am - 10:53 amSEA-DEN
2h 53mnonstop
Frontier Logo
8:55 pm - 10:59 pmDEN-SEA
3h 04mnonstop
$75Frontier
Find Deal
Tue, Sep 16 - Wed, Sep 24
Frontier Logo
7:00 am - 10:53 amSEA-DEN
2h 53mnonstop
Frontier Logo
8:55 pm - 10:59 pmDEN-SEA
3h 04mnonstop
$76Frontier
Find Deal
Wed, Sep 24 - Sun, Sep 28
Frontier Logo
7:00 am - 10:53 amSEA-DEN
2h 53mnonstop
Frontier Logo
10:29 pm - 12:30 amDEN-SEA
3h 01mnonstop
$77Frontier
Find Deal
Fri, Sep 5 - Sun, Sep 7
Frontier Logo
6:12 am - 10:08 amSEA-DEN
2h 56mnonstop
Frontier Logo
10:29 pm - 12:30 amDEN-SEA
3h 01mnonstop
$78Frontier
Find Deal
Wed, Oct 8 - Sun, Oct 12
Frontier Logo
8:43 pm - 12:35 amSEA-DEN
2h 52mnonstop
Frontier Logo
5:30 am - 7:33 amDEN-SEA
3h 03mnonstop
$79Frontier
Find Deal
Sun, Sep 28 - Tue, Sep 30
Frontier Logo
6:12 am - 10:08 amSEA-DEN
2h 56mnonstop
Frontier Logo
8:55 pm - 10:59 pmDEN-SEA
3h 04mnonstop
$80Frontier
Find Deal
Tue, Oct 28 - Wed, Oct 29
Frontier Logo
6:00 am - 9:51 amSEA-DEN
2h 51mnonstop
Frontier Logo
8:55 pm - 11:02 pmDEN-SEA
3h 07mnonstop
$81Frontier
Find Deal
Thu, Sep 4 - Mon, Sep 8
Frontier Logo
6:12 am - 10:08 amSEA-DEN
2h 56mnonstop
Frontier Logo
10:29 pm - 12:30 amDEN-SEA
3h 01mnonstop
$84Frontier
Find Deal
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$38
Best time to beat the crowds with an average 11% drop in price.
Most popular time to fly and prices are also 22% lower on average.
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 
Verified travelerFlew with Alaska AirlinesSEA-DENMar 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 DeltaSEA-DENApr 2025
Train from Denver airport to downtown is easy to use.
Verified travelerFlew with Alaska AirlinesSEA-DENMay 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 49m.

  • How many flights are there between Seattle and Boulder?

    50 direct flights run between Seattle and Boulder on a daily basis. On average, there are about 356 departures each week.

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

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

  • 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.

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 77 days before departure, on average.
  • Book at least 2 weeks before departure in order to get a below-average price.
  • High season is considered to be November, December and January. The cheapest month to fly is October.

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
Alaska AirlinesOverall score based on 10000 reviews
8.5Crew
7.1Food
8.1Boarding
7.8Comfort
7.0Entertainment
Airline reviews

Didn't care for the crowding at the gate area at SEA TAC. Not a fault of the airline.

8.0 ExcellentAnonymous, Aug 2025SEA - PHX
Read more Alaska Airlines reviews

Didn't care for the crowding at the gate area at SEA TAC. Not a fault of the airline.

Loved the staff ease of flying snacks and free movies and WiFi

you could have gotten me there on the day I was supposed to be there, not a day later. Paid for 3 nights at a VRBO and got to spend only 2 nights there.

Flight crew and gate staff were very polite and professional. They were very helpful and made my trip smooth and trouble free

Our flight was delayed BY 6 hours and the reason it was delayed because they needed a part which made me be worried about the plane. They did not have any TVS. Add the seeds and this was a very long flight. But they also only offered snacks, and even after we waited the 6 hours of being delayed with that, we still have to pay for drinks. If we we wanted one

all crew, pilots and attendants were fantastic. Both to and from flight to SEA, attendants went above and beyond.

Late boarding, but the flight was smooth and the crew was accommodating.

I requested wheelchair assistance in Seattle transferring gates and in Anchorage to get to baggage claim. No assistance was provided at all.

I was totally disgusted at the stewardesses supplying the three passengers in front of us in the exit row with multiple rounds of booze. They were loud and inappropriate using profanity to share stories. Our 3 and 7 year old he’s d it as well. Just flat out inappropriate and amazed AA wasn’t implementing a drink limit policy.

Arrived in Seattle to find our non stop flight was canceled and that we were rebooked to depart 16 hrs later. We stood in customer relation line for well over an hour and a half to find out what to do with our frozen fish that was checked bags and to get to our destination in a more timely fashion. There were only 2 Alaska reps working trying to help at least 2 cancelled flights that we know about. At one point a 3 rd rep showed up and shortly after one rep left stating she was going on break. There were atleast 50 people still in line. Finally We were rerouted through a different airport adding another stop the next day and given flight confirmation but no seat assignment stating ticket vouchers needed to be attached. We were then told to go to Alaska air luggage to request our fish be put in the freezer. The supervisor at baggage told us the freezer was full and that there was nothing he could do about it. Luckily he walked off and the ladies at the counter made sure our fish was put in the freezer. The following morning we had to be back to baggage to make sure our fish was tagged appropriately to get to our destination on a separate flight. . Both of our return flights we had to take we had to stand in line for the ticket people to try to find our ticket vouchers to attach to the boarding passes we were given. Al together our return took 31 hrs instead of the 12 hrs scheduled.

Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.

Southwest's seats are the least comfortable I have ever sat in.

The cabin was quiet for the redeye flight. The area was clean. The staff was great. The 787 Max was in good condition. Drawbacks were that the seat widths were tight for some passengers. The seat padding was at best average and for a long flight uncomfortable.

Southwest like most American domestic airlines, is a mediocre airline. But it is among the cheapest. Oh well.

My flight was delayed 50 minutes and we were rushed to board to then sit for 15 minutes until the pilot arrived. Unacceptable since we could have waited to board. Also the delayed flight was updated AFTER we boarded to more than the 10 minutes as originally stated.

Other than a bit of a delay, everything was good. Again, the boarding process and picking seats is the only thing I don't enjoy.

If we are going to have to pay for luggage, make it easier to do. Put something on the app during check-in so I don't need to do it at the kiosk. I've done it twice recently and I ended up having to pay at the desk because something went wrong at the kiosk in Tampa.

southwest just starting charging for luggage. hadnt realized it until it was too late. now out $70 when i couldve bought a carry on if i wouldve known. free bags was one of the only reasons i chose southwest over another airline (the other being no assigned seats, which is apparently also being changed). stupid business decision. wont be flying southwest anymore.

The quality of Southwest Airlines continues to degrade each time I fly with them. If it were not for the free luggage, I would probably choose another airline. Their prices are a little bit competitive, but way too high for the quality of the service. Southwest is not unique in this way. Domestic flight in the United States of America has continued to be a lower and lower quality product. Very sad when you compare the quality of domestic airlines to that of many international airlines around the world.

Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.

The flight attendants in SLC were rude. I arrived 40 minutes early to gate. Ticket said I needed check in for seat assignments and tried check in and attendants said they weren’t doing it. And proceeded to never call me to give me a ticket so when time to board I received the very last seat. Please relay to employees to do their job better..,

On this flight I felt the food offering was not as complete as on previous flights. The tomato salad was a bit off and there was nothing additional such a bread or butter. The breakfast was only one option, so you either ate what they had or ate nothing. The crew was efficient, but most seemed frustrated throughout the flight. The flight arrived early and was obstacle-free, so I’m overall quite happy, but the shine in the rest of the experience just wasn’t there.

The seats got pretty uncomfortable pretty fast. The armrests are bigger than on other planes, so I had less room in the actual seat. My butt hurt by the end of the flight. :/ comfort was the primary issue. The crew were fantastic!

I believe that a four-hour trip should have a meal. Delta had none.

Great flight with Delta! Boarding was quick and easy, the amenities were solid, and the plane was in great shape. The flight attendants had a fun, lively energy while staying professional. All in all, a smooth trip — even managed to catch up on some rest. Thanks, Delta!

I was uncomfortably cold on the plane. Other than that it was uneventful and therefore as enjoyable as a plane ride can be.

There was supposed to be a meal served, but there wasn’t and the major toilet was out of order

They made us board and then deboard due to mechanical issue which delayed the departure by almost 2 hours and we barely made our connecting flight. These quality checks should've been done before boarding not after.

Having to up charge for a seat assignment is not good. Delta can do better

I liked the friendliness of the staff. The cleanliness of all 3 planes.

Had to cancel first flight because Airporter Bus took over 3 hrs to get to airport which resulted in an extra $378 dollar fare . Is there anyway I can be reimbursed for initial fare since it was not my fault? Sent from my iPhone EJ Ledet

Excellent flight. Boarding was efficient and departure was on time. Smooth flight with on time arrival. Deplaning was also efficient.

Our flight was understandably diverted to a small regional airport in Laramie, Wyoming due to weather conditions, which I fully recognize and appreciate. However, the low rating stems from the experience that followed: passengers remained on board for over an hour without the option to deplane and stretch, despite the aircraft being stationary. Although the pilot opened the cabin door, only he was permitted to exit. Meanwhile, passengers grew increasingly uncomfortable as warm summer air entered the cabin through the open door, and being in the second row meant we were impacted immediately. While the flight attendants made efforts to keep everyone at ease, I believe allowing passengers to deplane briefly, given the extended delay, would have significantly improved the overall experience.

I never flew. Flight was canceled. DIA worst airport in the country. Avoid at all costs.

Very rough getting into denver. my kid threw up it was so rough.

Why wasn't this flight departure scheduled eith another crew so that it could leave on time? When we arrived in Denver we had so little time between flights we had run to the connecting flight. We should received some credit for the inconvenience.

I was supposed to be on business class at first class from Denver back to Miami due to weather changes. I missed my connection and it’s put on a flight to Fort Lauderdale. Instead of honoring my business class/1st class ticket, they put me in coach, but there were two first class seats open. I think it’s absolutely disgusting that I paid for first class $1300 ticket and they put me in economy and they had to open seats available and I have still not been refunded the difference. I ended up having to eat a snack box instead of the meal I was supposed to get and did not get home till 2 AM so I think that’s a little pathetic that I had to live off crackers for dinner And my poor dog ate some cheese and salami. Oh yes, apparently when they switched me to the new flight they forgot to mention I had a service dog

Excellent service despite turbulence during the flight. Flight attendants were remarkable!

Flight attendant moved my bag without notifying me and was rude to me when I asked him about it. There was no reason to move it.

The gate attendant let me walk right by her with a bag too big for the overhead compartment

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.

Late, terrible communication, horrible planning of passenger seating until the literal last minute. One of the worst flying experiences of my life. Y'all suck

First of all, we never got on the connecting flight to Denver. They delayed our flight for two hours. If we would have gotten on that flight, we would have been stuck in Denver for 13 hours. So we re- routed our flight for a straight through flight to Oklahoma two days later. THEN, they delayed that flight for two hours. After that we were able to finally get on our flight and come home. Frontier Airlines - one of the worst airlines I have ever been on.

Terrible communication with weather delay, lost baggage, near impossible to reach customer service

My tickets got canceled on me by your site and I didn't have a flight. Then you kept sending me emails on the status of q flight I didn't have tickets for.

The crew was mostly okay. The flight attendant who answered our questions was curt and unhelpful unfortunately. He seemed upset and I understand having off days.

Flight was delayed one hour. Notification to the crowd waiting near the gate was terrible…announcements were unclear and very hard to hear and therefore understand. Frontier does NOT send texts to notify, only email. The reader board over the gate itself was NEVER updated to indicate the gate had been changed. It’s like a bunch of children are running things.

We’ve all seen the YouTube vids of out of control passengers. But this was an instance of a highly aggressive, bully flight attendant. Yelling in the face of a vet with PTSD who was texting their family. And no , we had not yet been instructed to put our phones in airplane mode. My suggestion is that you should pay whatever difference there is in order to avoid Frontier airlines. Additionally, after 3hrs trying to get customer service frontier offered a $25 voucher. I declined. This experience was so traumatic. To be verbally assaulted and abused by a flight attendant that has the power to say “boo” and I miss my flight ( which was to a family member’s funeral ). Frontier is unsafe and I cannot impress enough how much I discourage anyone ( esp those with any kind of disability like PTSD ) flying on Frontier.

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