$55 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 11/16. 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

Sat, Nov 15 - Sun, Nov 16
Frontier Logo
12:58 pm - 4:57 pmSEA-DEN
2h 59mnonstop
Frontier Logo
6:00 am - 1:37 pmDEN-SEA
8h 37m1 stop
$96Frontier
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Fri, Dec 12 - Mon, Dec 15
Delta Logo
7:35 pm - 11:21 pmSEA-DEN
2h 46mnonstop
Delta Logo
6:05 am - 8:15 amDEN-SEA
3h 10mnonstop
$97Delta
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Wed, Nov 19 - Wed, Nov 26
Multiple Airlines Logo
5:20 am - 10:35 amSEA-DEN
4h 15m1 stop
Multiple Airlines Logo
9:44 am - 11:56 amDEN-SEA
3h 12mnonstop
$98Multiple Airlines
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Sun, Jan 11 - Sun, Jan 18
Frontier Logo
6:07 pm - 3:58 amSEA-DEN
8h 51m1 stop
Frontier Logo
10:16 am - 12:26 pmDEN-SEA
3h 10mnonstop
$100Frontier
Find Deal
Wed, Dec 24 - Mon, Dec 29
Frontier Logo
1:25 pm - 5:18 pmSEA-DEN
2h 53mnonstop
Frontier Logo
10:16 am - 12:30 pmDEN-SEA
3h 14mnonstop
$101Frontier
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Thu, Dec 4 - Thu, Dec 11
Frontier Logo
11:01 am - 8:12 pmSEA-DEN
8h 11m1 stop
Frontier Logo
9:42 am - 11:53 amDEN-SEA
3h 11mnonstop
$102Frontier
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Thu, Nov 13 - Wed, Nov 19
Multiple Airlines Logo
12:58 pm - 4:57 pmSEA-DEN
2h 59mnonstop
Multiple Airlines Logo
11:31 am - 3:37 pmDEN-SEA
5h 06m1 stop
$103Multiple Airlines
Find Deal
Fri, Nov 14 - Sun, Nov 16
Delta Logo
7:40 pm - 11:27 pmSEA-DEN
2h 47mnonstop
Delta Logo
6:05 am - 8:13 amDEN-SEA
3h 08mnonstop
$109Delta
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Sun, Nov 16 - Mon, Nov 17
Alaska Airlines Logo
5:20 am - 10:35 amSEA-DEN
4h 15m1 stop
Alaska Airlines Logo
8:02 pm - 10:13 pmDEN-SEA
3h 11mnonstop
$119Alaska Airlines
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Mon, Nov 17 - Wed, Nov 19
Alaska Airlines Logo
5:20 am - 10:35 amSEA-DEN
4h 15m1 stop
Alaska Airlines Logo
11:31 am - 3:37 pmDEN-SEA
5h 06m1 stop
$128Alaska Airlines
Find Deal

Everything you should know

Cheapest round-trip
$96
Overall average: $193
Frontier
Sat 11/15Sun 11/16
SEA - DEN • Non-stop
Cheapest non-stop
$94
Typical prices: $124-$297
Multiple Airlines
Wed 11/19Thu 11/20
SEA - DEN • Non-stop
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Boulder!
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$55
Best time to beat the crowds with an average 13% drop in price.
Most popular time to fly with an average 19% 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 
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 42m.

  • 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 353 departures each week.

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

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

  • 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 Delta for $55. Frontier offered a round-trip connection from $96 and Delta from $97.

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 1 week 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 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
Alaska AirlinesOverall score based on 11193 reviews
8.5Crew
7.1Food
7.0Entertainment
7.8Comfort
8.1Boarding
Airline reviews

Almost 3 hr delay in Settle with very little information available to passengers. They boarded the plane and we waited for a long time inside the plane as well.

2.0 MediocreAnonymous, Oct 2025SEA - STS
Read more Alaska Airlines reviews

Almost 3 hr delay in Settle with very little information available to passengers. They boarded the plane and we waited for a long time inside the plane as well.

This was our first time flying with Alaska. It was a seamless experience, with comfortable seats and leg room. Staff were friendly and helpful.

Flight on time. Crew good. Seating Bad. Have to pay extra on a not cheap flight to avoid being next to toilet.

The crew was great! Passengers were nice. Just an fyi that I heard several of them complain that the snack was not gluten free. Many people got handed the snack and then promptly gave it back to the flight attendant. Might be good to look into another option as such a high percentage of people in CO and WA are gf. Cheers!

Food and entertainment not applicable - standard drinks and cinnamon cookies; crew did not do a song and dance for us so no entertainment. I like the slightly better leg room than American Airlines - at least it felt that way. Flight crew and atmosphere seemed more welcoming than American, too.

It was fine, mostly I was just happy to be on my last leg home. No in flight entertainment but that's forgivable since it was only a 2 hour flight.

Was delayed in Newark 24 hours due to mechanical problems. The staff was very helpful in trying to make the best of a trying situation. In SeaTac, they changed gates and times. Usually have no problems from SeaTac.

Flight was cancelled, then rebooked on a flight that I was unable to get through since they had closed the gate.

Terrible. We were bumped off our flight to another and weren't sent notice until we were on our prior flight. We got home four hours later and the airline couldn't have cared less.

Continuously changing delayed departure time. Too much waiting for a short flight. Driving would have been faster.

All was good. I just had a hard time getting connected to the WiFi/internet during the flight

Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.

Great flight. Outstanding Service. Southwest was able to put us on a direct flight to Denver when the connection could have been affected by a later arrival to Baltimore. The direct flight was less expensive that the flight with the connection in Baltimore.

Delays delays delays. Late taking off, late landing, wait for a gate, etc.

Boarded on time but once we were ready for take off, the crew determined that, although every seat was taken, somehow someone was on the wrong flight. Delay, delay delay, announcements and ended up with one person checking EVERY ID against their passenger Manifest only to figure out it was a "clerical error." We departed 54 minutes late causing me to run in the St. Louis Airport to make my connection and lose the priority boarding spot I had paid for. Unnecessary delay.

I was re-booked onto another flight because my original flight was delayed and I would have missed my connector. I ended up in the “C” group after paying extra to be in the “A “ group on the original flight. At least if you’re going to re-book people, re-book them into the same group.

Flight was delayed due to plane not passing inspection And one of the crew had to time out and we had to wait for another one A 3 hour delay

mandatory demand customer to check their carry on because not enough people check bags.

Connecting flight is on time and boarding was a breeze!

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.

They ended up paying for the bag twice, but the counter wouldn't take my baggage receipt. Left it to me to resolve. Not sure how to resolve the issue.

The customer service before board was very rude and when I expressed my concerns about making the connecting flight she laughed and told me I bought the wrong ticket. I explained once it showed the flight was delayed it no longer let me change seats or anything. I was trying to upgrade to make sure I would get to the next gate on time.

Non stop on long haul is the way to go. Great experience

The flight used a B767 with a very old interior from before 2014. The entertainment system did not work at all during the flight despite attempts to reset the system. It was like they flew this route just to be competitive.

They changed planes and the new plane couldn’t carry enough fuel to fly across the country so we had to stop in Kansas City to refuel. Flight was delayed .

Flight was too crowded and seats are too small, especially since passengrs are getting larger. Having a middle seat is ALWAYS tough! Woman on my left was large & kept creeping in to my space. Flight personnel were great! Have more savory rather than sweet snacks please.

Flight was crowded and the woman sitting on my left was large & kept crouching in to my space. You need bigger seats or smaller passengers to fit into the seats you DO have! Snack were OK. Would appreciate if airlines had more savory rather than sweet snacks, thank you!

Delayed flight (1hour) plus a long layover after an overnight flight with no backup plane available.

We were delayed, which I think had to do with air traffic control. Otherwise, everything was great.

The boarding process needs to be refined. Sometimes the gate crew calls out the zones and then flip to showing the.zones boarding on the gate monitor display. So, unless you are huddled around the gate lanes watching the monitor, you could miss your boarding zone. Suggest the zones be announced each time a new zone is allowed to board.

The entertainment available didn’t work for anyone on the flight. Long 6 hr flight with no entertainment option and the staff didn’t know until an hour into the flight when we made sure they knew about it. They had no way to fix it.

Late FA meant slow boarding. WiFi did not work. I’m a medium plus sized passenger. The seatbelt was for the first time ever barely fitting. And we delayed on the tarmac 40 min

My husband and I had boarded the flight from Denver to Chicago, and one of the last passengers to get on the plane opened the overhead bin above my husband's seat and threw his bag out of the bin to make space for his own. He said, "Mine is bigger!" The flight attendant supported the new passenger. They didn't care that my husband has two artificial knees and must have the foot room in front of his seat to be able to fit his legs in -- and to be able to stand, much less walk, at the end of the flight. I have never seen this happen before, and it was a disaster.

Terrible. They wouldn't allow me on my flight on the 14th..

I understand stuff happens, but plane failures are likely due to lack of maintenance. Additionally, air conditioning wasn't working, no snack/drink service, no WiFi. Fortunately, the crew was communicative and light-hearted. United grabbed another plane and we were able to get to our destination.

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.

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.

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.

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