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$63+ Cheap flights from Washington, D.C. (WAS) to Boulder, CO

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 2/28. Fares are subject to change and may not be available on all flights or dates of travel.
WAS — DEN
Jan 17 — Jan 241
Sat 1/17
Sat 1/24
1 adult, Economy
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Cheapflights Tip: The best prices from Washington, D.C. to Boulder are usually found in August or January, booked 85 days in advance, depart on a Wednesday or Saturday and return on a Friday

Cheap flight deals from Washington, D.C. to Boulder

Cheapest flights from Washington, D.C. to Boulder
Explore the most affordable flight options available from Washington, D.C. to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on December 18, 2025.

This Mytrip deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/312:00 pmDCA - DEN
Nonstop4h 15mFrontier
Sat 1/104:38 pmDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/16$194
This Kiwi.com deal was found by Cheapflights users on 12/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/242:35 pmIAD - DEN
1 stop29h 22mMultiple Airlines
Wed 1/76:00 amDEN - IAD
1 stop8h 50mMultiple Airlines
Deal found 12/18$221
This Mytrip deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/292:09 pmIAD - DEN
1 stop20h 39mFrontier
Thu 1/89:44 amDEN - IAD
1 stop20h 11mFrontier
Deal found 12/16$232
This Mytrip deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/299:30 pmBWI - DEN
1 stop13h 08mFrontier
Thu 1/86:00 amDEN - BWI
1 stop10h 27mFrontier
Deal found 12/16$232
This CheapOair deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/292:09 pmIAD - DEN
1 stop20h 39mFrontier
Mon 1/126:00 amDEN - IAD
1 stop7h 27mFrontier
Deal found 12/16$234
This CheapOair deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/299:30 pmBWI - DEN
1 stop13h 08mFrontier
Mon 1/511:59 pmDEN - BWI
1 stop20h 04mFrontier
Deal found 12/16$234
This Kiwi.com deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/298:00 amDCA - DEN
Nonstop4h 13mFrontier
Tue 1/67:36 amDEN - DCA
Nonstop3h 26mFrontier
Deal found 12/16$236
This Frontier deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/298:00 amDCA - DEN
Nonstop4h 13mFrontier
Sat 1/104:38 pmDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/16$239
This Super.com deal was found by Cheapflights users on 12/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/298:00 amDCA - DEN
Nonstop4h 13mFrontier
Mon 1/124:38 pmDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/17$246
This Mytrip deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/298:00 amDCA - DEN
Nonstop4h 13mFrontier
Thu 1/811:38 amDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/16$249
This Orbitz deal was found by Cheapflights users on 12/17. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/295:42 pmBWI - DEN
1 stop17h 06mFrontier
Wed 12/317:00 amDEN - BWI
1 stop26h 44mFrontier
Deal found 12/17$254
This eDestinos deal was found by Cheapflights users on 12/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/317:01 pmIAD - DEN
2 stops30h 12mFrontier
Sat 1/1011:59 pmDEN - IAD
1 stop29h 41mFrontier
Deal found 12/16$255

Find flight deals from Washington, D.C. to Boulder

Keep the following information in mind while searching for Washington, D.C. to Boulder flight deals. Data was last updated December 18, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$133
(Frontier)

One-way from

$63
(Trip.com)

Popular in

December

Cheapest in

August

Average price

$359
Provider with most accurate pricing for Washington, D.C. (WAS)-Denver Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Washington, D.C. (WAS)-Denver Intl flights.
Search Deals
From Washington, D.C. (WAS) to Boulder
Search Deals
One-way flight from Washington, D.C. (WAS) to Boulder
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($11 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($8 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Washington, D.C. to Boulder that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 18, 2025.
Use the filters below to find and compare flights from Washington, D.C. to Boulder that are best for you.

Fly from

Washington, D.C.

Fly to

Boulder

Route

Depart

Return

Price

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 1/17

3:45 pm-5:50 pm

Nonstop4h 05m

Denver Intl

Sat 1/24

5:00 pm-10:10 pm

Nonstop3h 10m

$177

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Fri 1/16

2:00 pm-4:22 pm

Nonstop4h 22m

Denver Intl

Fri 1/23

4:38 pm-9:59 pm

Nonstop3h 21m

$181

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Wed 2/18

7:42 pm-9:47 pm

Nonstop4h 05m

Denver Intl

Mon 2/23

11:59 pm-5:18 am

Nonstop3h 19m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Tue 1/13

5:30 pm-7:35 pm

Nonstop4h 05m

Denver Intl

Sat 1/17

5:00 pm-10:10 pm

Nonstop3h 10m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 1/10

3:45 pm-5:50 pm

Nonstop4h 05m

Denver Intl

Sat 1/17

5:00 pm-10:10 pm

Nonstop3h 10m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Wed 2/18

7:00 am-2:00 pm

1 stop9h 00m

Denver Intl

Tue 2/24

12:59 am-9:08 am

1 stop6h 09m

$217

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 1/31

10:47 am-3:38 pm

1 stop6h 51m

Denver Intl

Sat 2/7

3:07 pm-11:06 pm

1 stop5h 59m

$217

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Thu 1/8

3:21 pm-12:59 am

1 stop11h 38m

Denver Intl

Sun 1/11

9:44 am-8:56 pm

1 stop9h 12m

$217

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Fri 2/20

5:19 pm-7:40 pm

Nonstop4h 21m

Denver Intl

Mon 2/23

6:00 am-11:20 am

Nonstop3h 20m

$217

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 1/10

3:45 pm-5:50 pm

Nonstop4h 05m

Denver Intl

Tue 1/13

4:45 pm-9:55 pm

Nonstop3h 10m

$217

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/17

Showing 1-10 of 60 results
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Best time to book a flight from Washington, D.C. to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder from Washington, D.C. with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

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

How far ahead should I book a flight from Washington, D.C. to Boulder?

Use this chart to determine the optimal time to book a round-trip flight from Washington, D.C. to Boulder. Price data was last updated on December 12, 2025.

The price you pay for your flight from Washington, D.C. to Boulder may vary depending on when you book. For the best chance of a lower fare, look to book 85 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from Washington, D.C. to Boulder?

Currently, January is the cheapest month in which you can book a flight from Washington, D.C. to Boulder (average of $85). Flying from Washington, D.C. to Boulder in June is currently the most expensive (average of $173). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from WAS to BD9?

Find hourly flight availability from Washington, D.C. to Boulder. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated December 18, 2025.

A simple way to save on the total cost of your ticket is to fly from Washington, D.C. to Boulder in the evening. If you’re flexible enough to do this you can expect to save up to 17% on your trip compared to booking a flight in the afternoon.

What is the cheapest day to fly from Washington, D.C. to Boulder?

Use this chart to determine the cheapest time to fly round-trip from Washington, D.C. to Boulder. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Washington, D.C. to Boulder flight should consider departing on Saturday at noon when fares are most often at their lowest. Sunday evenings flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Washington, D.C. to Boulder

Explore weekly flight availability from Washington, D.C. to Boulder. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated December 18, 2025.

The most flights from WAS to BD9 are scheduled on a Wednesday (28 on average). You will have fewer flight options on Friday, which is when the least amount of flights are scheduled (3 on average).

How much does it cost to fly round-trip from Washington, D.C. to Boulder?

Reviews of airlines servicing Boulder

Get insights into the airlines that provide service to Boulder. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Boulder. Reviews last updated December 18, 2025.
Read through reviews of airlines operating flights from Washington, D.C. to Boulder, such as Southwest, Delta, and United Airlines. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Southwest
7.9
Good
4,250 reviews
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Delta
7.9
Good
8,005 reviews
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
United Airlines
7.4
Good
9,092 reviews
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
American Airlines
7.2
Good
11,055 reviews
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am
Frontier
5.8
Fair
3,081 reviews
Southwest
7.9
Good
4,250 reviews

Boarding

8.1

Food

7.0

Overall

7.9

Entertainment

7.5

Crew

8.6

Comfort

8.0

Reviews

1 / 20
2.0
Mediocre

Thomas,Dec 2025

SEA - DEN

Plane two hours late in leaving 1:00 pm west coat time got home next day at 2:45am most car rental places are closed and don’t open till 5am

Related info for your journey

Find useful and relevant information for your journey from Washington, D.C. to Boulder. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from Washington, D.C. to Boulder?

    A quick flight from Washington, D.C. to Boulder can take about 4h 05m. Southwest provides one of the quickest options available for as low as $177. Airlines will cover a distance of 1448 mi. Generally, flights for this route are nonstop.

  • What are the cheapest airlines to fly from Washington, D.C. to Boulder one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $59. Users have also found prices from $88 and $98 on Southwest and American Airlines, respectively.

  • What are the most popular routes from Washington, D.C. to Boulder?

    Most travelers choose Washington, D.C. Dulles Intl - Denver Intl, Baltimore/Washington - Denver Intl or Washington, D.C. Reagan-National - Denver Intl when deciding on the best route from Washington, D.C. to Boulder.

  • What are the most reliable airlines from Washington, D.C. to Boulder?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Washington, D.C. to Boulder on time: Avianca (87%), Copa Airlines (84%), Ethiopian Air (84%).

  • What are the cheapest flights from Washington, D.C. to Boulder?

    Looking at all options, your cheapest flight can be booked for $128. While the most popular route (Washington, D.C. Dulles Intl - Denver Intl) can be booked for $177 on average, our data indicates $866 when flying from Washington, D.C. to Boulder.

  • Can I find deals for flights from Washington, D.C. to Boulder that include hotel bookings?

    Yes. In addition to deals on Washington, D.C. to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Washington, D.C. to Boulder?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Washington, D.C. to Boulder.

  • Can I find deals for business class flights from Washington, D.C. to Boulder?

    Yes. Cheapflights offers flight deals from Washington, D.C. to Boulder by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Washington, D.C. to Boulder?

    Currently, January is the cheapest month in which you can book a flight from Washington, D.C. to Boulder (average of $85). Flying from Washington, D.C. to Boulder in June is currently the most expensive (average of $173). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for Washington, D.C. to Boulder

See prices for flight routes from nearby airports that may be better suited for you.
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Top 6 airlines flying from Washington, D.C. to Boulder

Discover the top 6 airlines that operate flights from Washington, D.C. to Boulder. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$92Average$240FlexibilityNo cancel feeOn-time62%
JetBlueCheapest$128Average$450FlexibilityNo cancel feeOn-time62%
DeltaCheapest$138Average$315FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$160Average$364FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$178Average$367FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$214Average$382FlexibilityNo cancel feeOn-time69%

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