$73 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 7/1. 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
$142
Typical prices: $365-$197
Frontier
Thu 6/4Tue 6/9
SEA - DEN • Non-stop
Cheapest non-stop
$151
Typical prices: $357-$196
Frontier
Tue 6/9Fri 6/12
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
Useful Info
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

Thu, Jun 4 - Tue, Jun 9
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
8:44 am - 6:57 pm
DEN
-
SEA
11h 13m
1 stop
$142Frontier
Fri, Jun 5 - Tue, Jun 9
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
8:44 am - 6:57 pm
DEN
-
SEA
11h 13m
1 stop
$144Frontier
Mon, Jun 8 - Wed, Jun 24
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
8:44 am - 6:57 pm
DEN
-
SEA
11h 13m
1 stop
$147Frontier
Mon, Jun 8 - Tue, Jun 9
Frontier Logo
8:20 pm - 3:58 am
SEA
-
DEN
6h 38m
1 stop
Frontier Logo
7:45 am - 9:48 am
DEN
-
SEA
3h 03mnonstop
$148Frontier
Mon, Jun 8 - Wed, Jun 10
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
8:44 am - 6:57 pm
DEN
-
SEA
11h 13m
1 stop
$149Frontier
Tue, Jun 9 - Sun, Jun 14
Frontier Logo
7:41 pm - 11:36 pm
SEA
-
DEN
2h 55mnonstop
Frontier Logo
7:45 am - 9:48 am
DEN
-
SEA
3h 03mnonstop
$151Frontier
Wed, Jun 3 - Mon, Jun 8
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
10:33 am - 10:35 am
DEN
-
SEA
25h 02m
1 stop
$152Frontier
Tue, Jun 9 - Wed, Jun 10
Frontier Logo
7:41 pm - 11:36 pm
SEA
-
DEN
2h 55mnonstop
Frontier Logo
7:45 am - 9:48 am
DEN
-
SEA
3h 03mnonstop
$153Frontier
Wed, Jun 3 - Sat, Jun 6
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
8:41 am - 7:05 pm
DEN
-
SEA
11h 24m
1 stop
$154Frontier
Wed, Jun 3 - Tue, Jun 9
Frontier Logo
7:50 pm - 11:54 pm
SEA
-
DEN
3h 04mnonstop
Frontier Logo
12:14 pm - 2:18 pm
DEN
-
SEA
3h 04mnonstop
$157Frontier
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$73
Best time to beat the crowds with an average 28% 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?

    58 direct flights run between Seattle and Boulder on a daily basis. On average, there are about 408 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 $56 and Hawaiian Airlines from $70.

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 61 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 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.
7.9
Alaska AirlinesOverall score based on 12378 reviews
7.8Comfort
8.5Crew
7.0Entertainment
8.1Boarding
7.0Food
Airline reviews

Thank you to everyone, the crew and pilots.. they were so amazing!!

10.0 ExcellentAngel, May 2026
SEA - BOS
Read more Alaska Airlines reviews

Thank you to everyone, the crew and pilots.. they were so amazing!!

Crew was so kind, flight was easy, thank you so much for everything

The plane was to narrow. Uncomfortable seats.. Kayak is Awesome!

I had to cancel this trip due to medical reasons. I took out flight insurance but I was unable to cancel my reservation on either Kayak or Alaska. I need proof that I did not take this flight to get my refund. I have tried for a week and a half together that information from either Kayak or Alaska but so far I have gotten no response. I am very disappointed!

We had paid for window seats just to not get window seats. When we ask the flight attendant to switch seats she said no because it was a full flight. It was the the worst experience I had ever.

The crew seem untrained and uncertain no one ever checked up on us in our first class cabin. I had to ask for water four times and the lady kept saying she was busy when they weren't really doing anything. Had to walk to the back of the plane to get water for myself. Crew seem new and unexperience. You can tell this by the fumbling they kept making trying to fight. (I miss Hawaiian air.)

Alaska airlines agent helped me greatly to reschedule my flight. The flight was also very comfortable and the flight attendants were very friendly.

The crew was great and everything went smoothly coming and going.

My window seat did not have a window. I chose seat 11A thinking I would have a view. I had a wall instead.

See what I wrote in the previous section. This was a terrible experience. I would like refund.. I even paid an extra $70 for an aisle seat closer to the front to ensure that I got off early enough to catch the next flight. The fact that the plane did not wait, and even left eearlier, knowing that the first flight came in late, and was moved to a terminal three train stops away is appalling. My friend that flew JetBlue, their flight was delayed and came in later and the connecting flight WAITED for them. How is it that JetBlue could do that, and Alaska could not.

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

I'm glad it wasn't only 75% full because I could get a good seat

if I was good. Not happy that I have to pay extra money to get the seat I need for lake room, but I guess that’s a sign of the times.

Seats were very comfortable. They tilted back. Drinks and snacks were free and served 3 times. Attendants were awesome.

Plane was clean and comfortable. Flight attendants and gate staff were professional, friendly and efficient. Boarding and deplaning were orderly and efficient. All in all, the typical excellent Southwest experience.

Truly terrible. Will never willingly fly southwest again. Seats are worse than before they switched to assigned seating. One flight attendant was the opposite of helpful (rude, unhelpful, dismissive, and as my stranger seatmate said unprompted: a total prick). This caused me, 15 minutes into the flight, to book an alternate return flight home on a competing airline (first class 1.2k purchase instead of my existing planned flight) just so I would not have to ever be on that aircraft, with that terrible service person, with those horrific seats ever again.

Not having a five hour delay with little notice! The crew was very kind, though, and just as tired as we passengers were. The flight didn't depart until nearly 1 am...and no reason was ever given.

The entire experience from boarding to landing was amazing! The crew were very friendly. Will definitely be back.

no service at all due to turbulence. they should've at least given us snacks, there were only 10 people on the entire flight.

First time I've had to use the disabled accommodations. And I could not have had a better experience with Southwest, i was having trouble getting from one terminal to another due to my heart failure. And the next thing I know a Southwest agent had made sure. I had a wheelchair at all my flights. Can't thank them enough.

Enjoyed it very much. Especially liked the free WiFi that Delta offers.

Smooth flight. Left on time, and got in 15 minutes early. Onboard video was great

For some reason, TSA Atlanta didn’t have my bag on the flight on time and they don’t have to provide Delta a reason for that.

WiFi didn’t work on two of four planes. Flight attendants were not overly friendly or welcoming. Planes were extremely slow to board and deplane.

Delta does a great job with entertainment and free wifi. I can still be in touch with my colleagues while in the air.

Aside from a completely packed plane, I really have no complaints.

Bus to plane was delayed for no apparent reason and our luggage was still on the belt when they shut it off. Took about 20 minutes to turn it back on to get our luggage.

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.

It was good overall except from Omaha to Denver when flight a was a repeatedly delayed apparently due to some issue at Denver. Communications could have been handled better. I had to board then deboard with luggage and board again

Booked through Kayak Business, had a seat in middle and towards back due to booking rate, not comfortable.

They told us yesterday APR21st that they were cleaning the plane and we got delayed. After that they said they didn't had any crew for the flight so they cancelled the flight till next day.

The flight crew on this leg of my trip was very friendly and pleasant. Every one of them was humorous, as well as helpful and accommodating. This group was BY FAR the best crew I’ve flown with. They deserve kudos.

The entertainment options on the seat back video boards were nice.

The boarding process was straightforward. One pertinent observation regarding all boarding procedures is that if an individual requires assistance or possesses a special status and is part of preboarding, it is advisable to limit the number of passengers who can preboard with them, rather than the entire, sometimes large, companion groups. The seats are uncomfortable, and the entertainment options are significantly inferior compared to other airlines. During the snack service, I requested an additional bag of snacks, but my request was denied. Initially, the flight attendant agreed to my request.becoming a strange accurate moment. The flight duration was four hours.

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.

Frontier scheduled a 40 minute connection in DEN. What they failed to mention was that they “close the doors” 20 mins prior to departure, which means you only have 20 mins. Not enough time. Possibly against DOT regulations. Filing complaint.

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

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

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