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$47+ 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 3/7. Fares are subject to change and may not be available on all flights or dates of travel.
WAS — DEN
Feb 28 — Mar 71
Sat 2/28
Sat 3/7
1 adult, Economy
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Cheapflights Tip: The best prices from Washington, D.C. to Boulder are usually found in February or August, booked 76 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 January 29, 2026.

This Frontier deal was found by Cheapflights users on 1/28. 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 2/258:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Wed 2/251:39 pm
DEN
-
DCA
Nonstop3h 20m
Frontier
Deal found 1/28$103
This Kiwi.com deal was found by Cheapflights users on 1/27. 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 2/2810:29 am
IAD
-
DEN
1 stop13h 06m
Frontier
Sat 3/78:50 am
DEN
-
IAD
1 stop13h 41m
Frontier
Deal found 1/27$106
This Super.com deal was found by Cheapflights users on 1/27. 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.
Fri 2/276:00 pm
DCA
-
DEN
Nonstop4h 16m
Frontier
Sun 3/87:35 am
DEN
-
DCA
Nonstop3h 27m
Frontier
Deal found 1/27$107
This Frontier deal was found by Cheapflights users on 1/28. 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.
Sat 2/212:00 pm
DCA
-
DEN
Nonstop4h 22m
Frontier
Wed 2/257:48 am
DEN
-
DCA
Nonstop3h 27m
Frontier
Deal found 1/28$108
This Cheapflightsfares deal was found by Cheapflights users on 1/27. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 2/228:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Wed 2/251:39 pm
DEN
-
DCA
Nonstop3h 20m
Frontier
Deal found 1/27$111
This Frontier deal was found by Cheapflights users on 1/27. 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.
Thu 2/198:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Wed 2/251:39 pm
DEN
-
DCA
Nonstop3h 20m
Frontier
Deal found 1/27$112
This Kiwi.com deal was found by Cheapflights users on 1/27. 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 2/2810:29 am
IAD
-
DEN
1 stop13h 06m
Frontier
Wed 3/42:15 pm
DEN
-
IAD
1 stop18h 18m
Frontier
Deal found 1/27$114
This Cheapflightsfares deal was found by Cheapflights users on 1/28. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 2/188:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Sun 2/227:48 am
DEN
-
DCA
Nonstop3h 27m
Frontier
Deal found 1/28$117
This Frontier deal was found by Cheapflights users on 1/28. 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 2/118:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Wed 2/187:48 am
DEN
-
DCA
Nonstop3h 27m
Frontier
Deal found 1/28$118
This Frontier deal was found by Cheapflights users on 1/27. 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 2/258:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Sat 2/287:33 am
DEN
-
DCA
Nonstop3h 27m
Frontier
Deal found 1/27$123
This Super.com deal was found by Cheapflights users on 1/27. 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.
Sat 2/218:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Mon 2/234:38 pm
DEN
-
DCA
Nonstop3h 21m
Frontier
Deal found 1/27$126
This Cheapflightsfares deal was found by Cheapflights users on 1/27. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 2/208:00 am
DCA
-
DEN
Nonstop4h 22m
Frontier
Thu 2/264:38 pm
DEN
-
DCA
Nonstop3h 21m
Frontier
Deal found 1/27$127

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 January 29, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$103
(Frontier)

One-way from

$47
(Trip.com)

Popular in

December

Cheapest in

February

Average price

$257
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 ($9 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($6 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in January 2026
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 January 29, 2026.
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 3/7

6:05 pm-8:10 pm

Nonstop4h 05m

Denver Intl

Wed 3/11

6:35 pm-11:40 pm

Nonstop3h 05m

$177

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Tue 2/24

3:40 pm-10:18 pm

1 stop8h 38m

Denver Intl

Wed 2/25

11:15 pm-8:03 am

1 stop6h 48m

$219

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Tue 5/12

6:00 am-10:15 am

1 stop6h 15m

Denver Intl

Thu 5/14

11:05 am-10:59 pm

1 stop9h 54m

$219

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Mon 5/4

6:00 am-10:15 am

1 stop6h 15m

Denver Intl

Wed 5/6

11:08 pm-7:59 am

1 stop6h 51m

$219

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 3/7

6:05 pm-8:10 pm

Nonstop4h 05m

Denver Intl

Tue 3/10

8:25 am-5:20 pm

1 stop6h 55m

$227

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Sat 2/21

3:10 pm-8:05 pm

1 stop6h 55m

Denver Intl

Wed 2/25

7:20 am-5:00 pm

1 stop7h 40m

$237

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Thu 3/19

5:50 am-7:45 am

Nonstop3h 55m

Denver Intl

Tue 3/24

6:35 pm-11:40 pm

Nonstop3h 05m

$237

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Thu 5/7

6:00 am-10:15 am

1 stop6h 15m

Denver Intl

Tue 5/12

11:08 pm-7:59 am

1 stop6h 51m

$238

Washington, D.C.Denver

DCA - DEN

DCADEN

Washington, D.C. Reagan-National

Mon 2/23

4:59 pm-10:18 pm

1 stop7h 19m

Denver Intl

Thu 2/26

11:15 pm-9:07 am

1 stop7h 52m

$240

Washington, D.C.Denver

IAD - DEN

IADDEN

Washington, D.C. Dulles Intl

Sat 2/21

5:05 am-7:05 am

Nonstop4h 00m

Denver Intl

Wed 2/25

6:00 am-4:50 pm

1 stop8h 50m

$247

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/29

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 January 23, 2026.

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 35 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 $76). 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 January 29, 2026.

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 22% on your trip compared to booking a flight at noon.

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 January 24, 2026.

Travelers seeking maximum savings on their Washington, D.C. to Boulder flight should consider departing on Tuesday 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 January 29, 2026.

The most flights from WAS to BD9 are scheduled on a Monday (30 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (17 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 January 29, 2026.
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
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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
8.0
Very good
4,267 reviews
Southwest
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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
8,128 reviews
Southwest
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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
9,215 reviews
Southwest
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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
11,205 reviews
Southwest
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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
5.7
Fair
3,056 reviews
Southwest
8.0
Very good
4,267 reviews

Food

7.0

Boarding

8.1

Comfort

8.0

Crew

8.6

Entertainment

7.5

Overall

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. 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 $58. Users have also found prices from $82 and $88 on JetBlue and Southwest, 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: Ethiopian Air (93%), Avianca (88%), United Airlines (87%).

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

    Looking at all options, your cheapest flight can be booked for $132. While the most popular route (Baltimore/Washington - Denver Intl) can be booked for $134 on average, our data indicates $859 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 $76). 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.
Dulles Intl to Denver flights
Reagan-National to Denver flights
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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 January 29, 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$82Average$235FlexibilityNo cancel feeOn-time62%
DeltaCheapest$118Average$310FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$160Average$383FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$177Average$368FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$188Average$409FlexibilityNo cancel feeOn-time69%
JetBlueCheapest$325Average$578FlexibilityNo cancel feeOn-time62%

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