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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 1/24. Fares are subject to change and may not be available on all flights or dates of travel.
WAS — DEN
Jan 11 — Jan 181
Sun 1/11
Sun 1/18
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 12, 2025.

This Super.com deal was found by Cheapflights users on 12/10. 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.
Thu 12/258:00 amDCA - DEN
Nonstop4h 13mFrontier
Mon 1/124:38 pmDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/10$201
This Trip.com deal was found by Cheapflights users on 12/11. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/258:00 amDCA - DEN
Nonstop4h 13mFrontier
Thu 1/811:38 amDEN - DCA
Nonstop3h 21mFrontier
Deal found 12/11$207
This Frontier deal was found by Cheapflights users on 12/11. 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.
Wed 12/318:00 amDCA - DEN
Nonstop4h 13mFrontier
Tue 1/137:35 amDEN - DCA
Nonstop3h 27mFrontier
Deal found 12/11$214
This CheapOair deal was found by Cheapflights users on 12/9. 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.
Tue 12/305:36 pmBWI - DEN
1 stop27h 39mFrontier
Thu 1/14:13 pmDEN - BWI
1 stop15h 58mFrontier
Deal found 12/9$220
This Kiwi.com deal was found by Cheapflights users on 12/10. 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.
Tue 12/308:50 pmBWI - DEN
1 stop13h 48mFrontier
Tue 1/611:22 amDEN - BWI
1 stop8h 41mFrontier
Deal found 12/10$224
This Frontier deal was found by Cheapflights users on 12/11. 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.
Wed 12/318:00 amDCA - DEN
Nonstop4h 13mFrontier
Thu 1/87:35 amDEN - DCA
Nonstop3h 26mFrontier
Deal found 12/11$225
This Kiwi.com deal was found by Cheapflights users on 12/10. 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.
Fri 12/196:00 amBWI - DEN
1 stop9h 33mFrontier
Wed 1/710:36 amDEN - BWI
1 stop9h 20mFrontier
Deal found 12/10$228
This CheapOair deal was found by Cheapflights users on 12/10. 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 12/154:00 pmIAD - DEN
1 stop18h 43mFrontier
Wed 12/1711:59 pmDEN - IAD
1 stop6h 47mFrontier
Deal found 12/10$234
This CheapOair deal was found by Cheapflights users on 12/10. 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.
Tue 12/235:36 pmBWI - DEN
1 stop27h 39mFrontier
Tue 12/306:25 amDEN - BWI
1 stop27h 21mFrontier
Deal found 12/10$234
This Kiwi.com deal was found by Cheapflights users on 12/10. 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.
Tue 12/309:58 pmIAD - DEN
2 stops35h 35mFrontier
Fri 1/166:13 pmDEN - IAD
1 stop14h 54mFrontier
Deal found 12/10$240
This Kiwi.com deal was found by Cheapflights users on 12/9. 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.
Sat 12/138:37 amBWI - DEN
1 stop25h 47mFrontier
Tue 12/1611:59 pmDEN - BWI
1 stop8h 22mFrontier
Deal found 12/9$240
This Gotogate deal was found by Cheapflights users on 12/9. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/229:58 pmIAD - DEN
1 stop27h 06mFrontier
Wed 1/76:00 amDEN - IAD
1 stop8h 50mFrontier
Deal found 12/9$241

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 12, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$136
(Super.com)

One-way from

$63
(Trip.com)

Popular in

December

Cheapest in

August

Average price

$358
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. 3% potential increase in price ($11 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($7 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 12, 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

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Tue 1/6

6:00 am-10:42 am

1 stop6h 42m

Denver Intl

Thu 1/8

11:38 am-4:59 pm

Nonstop3h 21m

$150

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Wed 1/21

9:05 am-11:15 am

Nonstop4h 10m

Denver Intl

Wed 1/28

4:45 pm-9:55 pm

Nonstop3h 10m

$177

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

Sun 2/22

6:00 am-11:20 am

Nonstop3h 20m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 2/7

4:11 pm-6:24 pm

Nonstop4h 13m

Denver Intl

Mon 2/9

11:59 pm-5:21 am

Nonstop3h 22m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sun 1/11

5:30 am-7:30 am

Nonstop4h 00m

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

Thu 1/29

10:32 pm-12:30 am

Nonstop3h 58m

Denver Intl

Tue 2/3

7:50 am-1:17 pm

Nonstop3h 27m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 1/10

8:15 am-10:27 am

Nonstop4h 12m

Denver Intl

Thu 1/15

11:59 pm-5:21 am

Nonstop3h 22m

$197

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Wed 2/11

6:00 am-10:08 am

1 stop6h 08m

Denver Intl

Tue 2/17

6:10 am-4:28 pm

1 stop8h 18m

$217

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Sat 1/10

6:00 pm-10:55 pm

1 stop6h 55m

Denver Intl

Sat 1/17

6:00 am-3:00 pm

1 stop7h 00m

$217

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Sat 1/10

6:05 am-10:24 am

1 stop6h 19m

Denver Intl

Tue 1/13

1:18 pm-9:34 pm

1 stop6h 16m

$217

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/10

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 5, 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, February is the cheapest month in which you can book a flight from Washington, D.C. to Boulder (average of $88). 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 12, 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 12, 2025.

The most flights from WAS to BD9 are scheduled on a Thursday (28 on average). You will have fewer flight options on Friday, which is when the least amount of flights are scheduled (19 on average).

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 12, 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
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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
4,253 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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
8,008 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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
9,095 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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
11,050 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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
3,084 reviews
Southwest
7.9
Good
4,253 reviews

Comfort

8.0

Boarding

8.1

Food

7.0

Crew

8.6

Entertainment

7.5

Overall

7.9

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 $197. Airlines will cover a distance of 1448 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • 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 $57. 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 Baltimore/Washington - Denver Intl, Washington, D.C. Dulles Intl - 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 (88%), Ethiopian Air (85%), United Airlines (85%).

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

    Looking at all options, your cheapest flight can be booked for $148. While the most popular route (Baltimore/Washington - Denver Intl) can be booked for $129 on average, our data indicates $881 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, February is the cheapest month in which you can book a flight from Washington, D.C. to Boulder (average of $88). 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

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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 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$106Average$241FlexibilityNo cancel feeOn-time62%
JetBlueCheapest$128Average$321FlexibilityNo cancel feeOn-time62%
DeltaCheapest$138Average$322FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$160Average$364FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$178Average$369FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$215Average$387FlexibilityNo cancel feeOn-time69%

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