$63 Find Cheap Flights from Washington, D.C. 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 Washington, D.C. to Boulder departing on 2/25. 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
$136
Overall average: $320
Frontier
Mon 2/23Fri 2/27
IAD - DEN • 1 stop
Cheapest non-stop
$135
Typical prices: $159-$312
Frontier
Mon 1/5Sat 1/17
DCA - DEN • Non-stop
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Flight Deals
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Flight Deals

Cheap Flights from Washington, D.C. to Boulder (WAS-DEN)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Washington, D.C. 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 Washington, D.C. to Boulder

Mon, Feb 23 - Fri, Feb 27
Frontier Logo
7:05 pm - 9:11 am
IAD
-
DEN
16h 06m1 stop
Frontier Logo
12:59 am - 10:21 am
DEN
-
IAD
7h 22m1 stop
$136Frontier
Sun, Jan 11 - Sun, Jan 18
Frontier Logo
8:01 am - 10:14 am
DCA
-
DEN
4h 13mnonstop
Frontier Logo
4:38 pm - 9:59 pm
DEN
-
DCA
3h 21mnonstop
$136Frontier
Fri, Jan 9 - Sun, Jan 11
Frontier Logo
6:00 pm - 8:12 pm
DCA
-
DEN
4h 12mnonstop
Frontier Logo
7:35 am - 1:01 pm
DEN
-
DCA
3h 26mnonstop
$138Frontier
Tue, Jan 6 - Sat, Jan 10
Multiple Airlines Logo
6:00 am - 10:42 am
DCA
-
DEN
6h 42m1 stop
Multiple Airlines Logo
7:35 am - 1:01 pm
DEN
-
DCA
3h 26mnonstop
$139Multiple Airlines
Thu, Feb 12 - Sat, Feb 14
Frontier Logo
8:00 am - 10:22 am
DCA
-
DEN
4h 22mnonstop
Frontier Logo
11:38 am - 5:00 pm
DEN
-
DCA
3h 22mnonstop
$141Frontier
Sun, Feb 1 - Wed, Feb 4
Multiple Airlines Logo
7:00 am - 12:45 pm
DCA
-
DEN
7h 45m1 stop
Multiple Airlines Logo
7:35 am - 1:02 pm
DEN
-
DCA
3h 27mnonstop
$143Multiple Airlines
Wed, Jan 7 - Sun, Jan 11
Frontier Logo
6:00 pm - 8:12 pm
DCA
-
DEN
4h 12mnonstop
Frontier Logo
7:35 am - 1:01 pm
DEN
-
DCA
3h 26mnonstop
$144Frontier
Thu, Feb 12 - Tue, Feb 17
Frontier Logo
8:00 am - 10:22 am
DCA
-
DEN
4h 22mnonstop
Frontier Logo
6:40 am - 12:04 pm
DEN
-
DCA
3h 24mnonstop
$145Frontier
Thu, Jan 15 - Fri, Jan 16
Frontier Logo
6:00 am - 12:21 pm
IAD
-
DEN
8h 21m1 stop
Frontier Logo
12:05 am - 11:07 am
DEN
-
IAD
9h 02m1 stop
$146Frontier
Fri, Feb 20 - Sat, Feb 21
Frontier Logo
6:00 pm - 8:16 pm
DCA
-
DEN
4h 16mnonstop
Frontier Logo
4:38 pm - 9:59 pm
DEN
-
DCA
3h 21mnonstop
$148Frontier
Useful Info

Good to know

Low seasonNovember
Cheapest flight$63
Best time to beat the crowds with an average 3% drop in price.
Most popular time to fly and prices are also 7% lower on average.
Flight from Baltimore to Denver

When to book flights from Washington, D.C. to Boulder

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

FAQs for booking flights from Washington, D.C. to Boulder

  • Which airports will I be using when flying from Washington, D.C. to Boulder?

    When flying out of Washington, D.C. you’ll be using one of these airports: Washington, D.C. Reagan-National or Washington, D.C. Dulles 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 Washington, D.C. to Boulder take?

    Direct flights cover the 1,471 miles separating Washington, D.C. and Boulder in about 3h 50m.

  • How many flights are there between Washington, D.C. and Boulder?

    34 direct flights run between Washington, D.C. and Boulder on a daily basis. On average, there are about 241 departures each week.

  • What’s the cheapest day of the week to fly between Washington, D.C. and Boulder?

    Consider leaving on a Friday and avoid Saturdays if you are looking for the best rates. For your return to Washington, D.C., you’ll find the best rates on Tuesdays and the most expensive ones on Saturdays.

  • How does KAYAK find such low prices on flights from Washington, D.C. 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 Washington, D.C. to Boulder.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Washington, D.C. to Boulder?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Boulder from Washington, D.C. 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 Washington, D.C. 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 Washington, D.C. with another airline.

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

    In the last 72 hours, the cheapest one-way ticket between Washington, D.C. and Boulder found on KAYAK was with Frontier for $57. Frontier offered a round-trip connection from $101 and JetBlue from $128.

Top tips for finding cheap flights from Washington, D.C. to Boulder

  • There is no airport in Boulder. Instead, you’ll be flying into Denver Airport when flying between Washington, D.C. and Boulder.
  • The cheapest flight from Washington, D.C. to Boulder was found 85 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 August.

Reviews of the top 5 airlines serving Washington, D.C. to Boulder

 
Need help choosing which airline to fly with from Washington, D.C. 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
SouthwestOverall score based on 4250 reviews
8.0Comfort
7.0Food
7.5Entertainment
8.6Crew
8.1Boarding
Airline reviews

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

8.0 ExcellentRussell, Dec 2025
SAN - OAK
Read more Southwest reviews

The boarding and seat assignment system no longer works for me, but I know it is being replaced. Otherwise, I am good with the overall experience.

The lead steward kept singing about "San Francisco" and hotel California---more annoying than humorous....needs work. Flight was smooth and on time.

Still a fan of open seating. Flight was on schedule and arrived on time. The 737 MAX is very comfortable.

Airline travel is always too cramped to really be pleasant, but the cabin crew on this flight did a pretty good job of making up for it by putting on some music during boarding and sprinkling a few funny remarks into the safety briefing and announcements, and just generally being friendly and helpful. It definitely reminded me of why I prefer the in-flight experience on Southwest!

No delays and arrived to destination 30 min early. Staff was super friendly.

San Diego airport is brand new, spacious, airy and very smooth checkin at SW baggage drop.

It was rough. The staff was unprofessional, the choice of on board drinks terrible, it was cramped in space at every airport, they always ran out of overhead bin space so they pressured people to check bags for free or we couldn’t leave on the plane— so I did check my bag to help, and they nearly lost my bag. My bag did not arrive on the luggage belt, another man on my flight and I had to waste our time going to the baggage office to search for our bags. I would only fly southwest again if it was my last choice. Also, my flights were consistently delayed over and over again— at one point they straight up told us we were waiting for the pilot to arrive.

Crew could have been friendlier, maybe I'm spoiled by SW crews. In flight wifi was good. Would be nice to have more food offerings on a 4 plus hour flight

Had to get off plane from prior flight even though I had to reboard same plane to continue to my final destination.

Everything a cheap airline should be at normal airline rates.

Original flight was cancelled and when i was rebooked by the airline, they couldn't seat me in the same type of seat as I had originally booked (went from window/aisle to middle/middle and one was a bulkhead seat, and other wasn't in the same class)

Lady Pilot was perfect in every way wheels up to wheels down communication, professionalism, excellent on time departure and on time arrival, excellent communication! Fantastic job with Superb attitude!!

The food is terrible. The staff is wonderful. Comfort is good.

Left on time, a bit delayed due to headwinds most of the trip.

I fly Delta all the time, have Platinum Medallion status. But this route seems to have major problems with delays and seems to never leave on time! Have only taken it twice in the last two weeks, and each time it had delays of more than 1 hour... very disappointed!!!!

Good seats in Main cabin, excellent service and excellent landing

My flight was cancelled with no explanation after I had already cleared security. I was given 4 options to rebook, only one being non-stop like I had paid for. I grabbed it. It was 4 plus hours later and then took off even later. Biggest complaint is that I booked early and had an aisle seat. They gave me a "window" seat in front of the exit row, so the seat did not decline. I weigh all of 103 #s and it was tight for me! For what I paid, I feel I was kind of ripped off. I think they should have given me the empty comfort seat for the inconvenience. There was no apology nor any explanation as to why the flight was cancelled. My guess is it benefitted Delta in some way.

Very smooth, on-time, and pleasantly uneventful flight. The team at the gate and on board were professional and genuinely courteous. The pilot kept us well updated throughout, and both takeoff and landing were steady and enjoyable without any drama. Just a good, solid flight. Thank you! 💗

Staff was exceptional! Everyone was kind, professional and friendly making the trip very pleasant. Thank you!

No lunch on a x-country flight scheduled for 10:50 am departure, arrived 5+ hrs later. That requires a black box label before you pay for the tickets. Worst, when I checked in online, it's specifically said that lunch was served on his flight for economy Plus passengers.

Not great experience - we were super late boarding due to issues with aircraft. Then when we finally all got onboard and seated and they started taxiing out to the runway they just stopped then turned around and went back to the airport. Apparently the crew “ran out of time” to legally fly us. They mentioned that they were about 2 minutes away from taking off. I understand the rules and safety but kinda wonder why they would have bothered boarding us in the first place? Had to go all the way back and de plane and then wait in a HUGE line to get a hotel (this is somewhere around 2:30am) finally got to hotel by Uber (no shuttle after 20min so gave up) and they ended up putting us all back on the same aircraft at 10am next morning so got about 2.5 hours sleep. They did give us. $250 credit, but it was a São Paulo Brazil flight out of Dulles. The flight and everything was fine.

Starlink wifi on the Embraer E175 is an excellent experience. I was able to connect and work from IAD all the way to approach into BTV.

7 hours delayed due to operational issues on United’s end. Basically laziness.

Short flight but an "eager to help" crew made the journey more enjoyable!

During booking, I kept trying submitting my payment from the Mexican website and it didn't work. After I had the idea to change it to the Canadian website, it worked but I had to be charged the equivalent of 50 CAD more. I received the clear instruction that I would only be able to check-in at the airport and that it was impossible to select a seat 24 hours before departure, that I had to pay 144 CAD to do so, although not only was I able to check-in 24 hours before departure, but I could have selected my seats for free then. All in all, I almost threw $200 out the window due to misleading information. Besides, the app kept crashing, the information to get to the gate on the app was inaccurate, my gate was switched and I was only informed once in the air (luckily I had noticed the departure pannel), I was not addressed in my language beforehand and even if I tried I was immediately answered in English (which meant the crew understood but didn't want to answer accordingly), there was only one snack & beverage service on my medium haul flight and no beverage service on my short haul flight. To be fair, the planes were comfortable, the crew apart from the language issue was helpful, dynamic and engaging, the plane was clean and the directions were clear and direct. United has a lot of potential to be one of my favourite airlines, but the devil is in the details and a lot of them missed the target.

Better WiFi. I cannot understand that in 2025, United is so behind on a technology that is now a necessity and still painfully unreliable, slow and keeps disconnecting.

Great service on board. Boarding a bit slow due to process. Food was pretty average.

Very small cramped plane for an international flight. Everything else was good, but it was maybe the smallest comfort-wise I've ever been on for longer than 3-4 hours and the trip was 7.5

Flight was delayed 3 hours. No food and drink vouchers was provided. They offered a mini pretzel bag and water .

Staff was rude. Didn’t give water for 2 hours. Worst service

I got sick nothing contagious but distressing and the care I received by Kayla? Keighly the flight attendant will be memorable for ever. Thank You

We were told the flight was delayed 5 times, then it was moved to the next day.

Flight delay was communicated before leaving for airport which caused it to be a non-event. Great flight and crew!

The flight attendant, a black woman with curly hair who sat near Row 21, was wonderful and kind.

Flight was delayed leaving Dallas. Arrived about 2 hours later than scheduled.

We were delayed for a “couple of maintenance issues.” They were resolved rather quickly but a computer glitch caused someone in the airport to have to bring a physical copy of the paperwork so we could leave. I don’t know where they had to drive from to get to our plane but it took forever & we were 1 1/2 hrs late in leaving. The flight itself was fine.

Because the plane was 90 degrees F, they would not let us board. I wish they had, because it meant we were delayed. It's Texas, of course it's hot. We would have survived.

It took way too long to diagnose and solve the problem of a broken crew member cabin seat. Though compensation for the volunteer who left the flight was very kind.

Our bags took a long time to get unloaded once we landed.

We fly American Airlines quite a bit. And we always fly business class when traveling internationally. We were a bit disappointed with the comfort of this particular plane as well as the entertainment options.

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.

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.

I missed a flight because of a delay. I had to buy a new ticket through Southwest.

Everything you need to know for your flight from Washington, D.C. to Boulder

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