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$49+ Cheap flights from San Francisco (SFO) 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 4/21. Fares are subject to change and may not be available on all flights or dates of travel.
SFO — DEN
Mar 31 — Apr 71
Mon 3/31
Mon 4/7
1 adult, Economy
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Cheapflights Tip: The best prices from San Francisco to Boulder are usually found in September or January, booked 30 days in advance, depart on a Wednesday or Saturday and return on a Friday

Cheap flight deals from San Francisco to Boulder

Keep the following information in mind while searching for San Francisco to Boulder flight deals. Data was last updated March 26, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$97
(Frontier)

One-way from

$49
(Frontier)

Popular in

December

Cheapest in

September

Average price

$218
Provider with most accurate pricing for San Francisco-Denver Intl flight deals.
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Provider most trusted by Cheapflights users for San Francisco-Denver Intl flights.
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From San Francisco to Boulder
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One-way flight from San Francisco to Boulder
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Highest demand for flights based on searches. 5% potential increase in price ($11 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in March 2025
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Find flight deals from San Francisco to Boulder

Cheapest flights from San Francisco to Boulder
Explore the most affordable flight options available from San Francisco to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 26, 2025.

This Frontier deal was found by Cheapflights users on 3/25. 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 4/233:33 pmSFO - DEN
Nonstop2h 42mFrontier
Wed 4/2310:38 pmDEN - SFO
Nonstop2h 55mFrontier
Deal found 3/25$97
This United Airlines deal was found by Cheapflights users on 3/25. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/155:00 amSFO - DEN
Nonstop2h 38mUnited Airlines
Sun 5/185:20 amDEN - SFO
Nonstop2h 50mUnited Airlines
Deal found 3/25$141
This Southwest deal was found by Cheapflights users on 3/25. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/207:00 amSFO - DEN
1 stop4h 30mSouthwest
Thu 4/247:55 amDEN - SFO
Nonstop2h 40mSouthwest
Deal found 3/25$147
This Kiwi.com deal was found by Cheapflights users on 3/25. 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 4/2210:33 amSFO - DEN
1 stop7h 24mMultiple Airlines
Sat 4/2610:38 pmDEN - SFO
Nonstop2h 55mMultiple Airlines
Deal found 3/25$154
This Hawaiian Airlines deal was found by Cheapflights users on 3/25. 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 Hawaiian Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/224:49 pmSFO - DEN
1 stop6h 10mHawaiian Airlines
Tue 4/297:00 amDEN - SFO
1 stop7h 32mHawaiian Airlines
Deal found 3/25$199
This Alaska Airlines deal was found by Cheapflights users on 3/25. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/288:00 amSFO - DEN
1 stop12h 15mAlaska Airlines
Fri 5/96:37 pmDEN - SFO
1 stop6h 04mAlaska Airlines
Deal found 3/25$201
This American Airlines deal was found by Cheapflights users on 3/25. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/13:23 pmSFO - DEN
1 stop5h 19mAmerican Airlines
Tue 7/156:07 pmDEN - SFO
1 stop5h 30mAmerican Airlines
Deal found 3/25$209
This Delta deal was found by Cheapflights users on 3/25. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/95:05 pmSFO - DEN
1 stop4h 25mDelta
Fri 5/167:17 pmDEN - SFO
1 stop4h 52mDelta
Deal found 3/25$217

Cheapflights Fare Finder

Customize your flight search to find flights from San Francisco 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 March 26, 2025.
Use the filters below to find and compare flights from San Francisco to Boulder that are best for you.

Fly from

San Francisco

Fly to

Boulder

Route

Depart

Return

Price

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Wed 4/23

3:33 pm-7:15 pm

Nonstop2h 42m

Denver Intl

Wed 4/23

10:38 pm-12:33 am

Nonstop2h 55m

$97

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Thu 5/15

5:00 am-8:38 am

Nonstop2h 38m

Denver Intl

Sun 5/18

5:20 am-7:10 am

Nonstop2h 50m

$141

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Sun 4/20

7:00 am-12:30 pm

1 stop4h 30m

Denver Intl

Thu 4/24

7:55 am-9:35 am

Nonstop2h 40m

$147

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Tue 4/22

10:33 am-6:57 pm

1 stop7h 24m

Denver Intl

Sat 4/26

10:38 pm-12:33 am

Nonstop2h 55m

$154

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Tue 4/22

4:49 pm-11:59 pm

1 stop6h 10m

Denver Intl

Tue 4/29

7:00 am-1:32 pm

1 stop7h 32m

$199

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Mon 4/28

8:00 am-9:15 pm

1 stop12h 15m

Denver Intl

Fri 5/9

6:37 pm-11:41 pm

1 stop6h 04m

$201

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Fri 5/9

5:55 am-12:04 pm

1 stop5h 09m

Denver Intl

Thu 5/15

5:30 am-8:56 am

1 stop4h 26m

$217

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Mon 4/14

7:50 am-3:22 pm

1 stop6h 32m

Denver Intl

Thu 4/17

8:09 am-12:16 pm

1 stop5h 07m

$258

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Mon 4/21

6:00 am-9:39 am

Nonstop2h 39m

$49

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

Thu 5/15

5:00 am-8:38 am

Nonstop2h 38m

$71

Flights are sorted by cheapest round-trip flights first.

Deals found on 3/24

Showing 1-10 of 16 results
1
2

Best time to book a flight from San Francisco to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder from San Francisco 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 San Francisco to Boulder

How far ahead should I book a flight from San Francisco to Boulder?

Use this chart to determine the optimal time to book a round-trip flight from San Francisco to Boulder. Price data was last updated on March 21, 2025.

Booking 30 days in advance of your planned departure date is, on average, the best time to get cheap flights from San Francisco to Boulder. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

What is the cheapest month to book a flight from San Francisco to Boulder?

Currently, October is the cheapest month in which you can book a flight from San Francisco to Boulder (average of $197). Flying from San Francisco to Boulder in March is currently the most expensive (average of $278). 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 SFO to BD9?

Find hourly flight availability from San Francisco 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 March 26, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from San Francisco to Boulder as you normally would.

What is the cheapest day to fly from San Francisco to Boulder?

Use this chart to determine the cheapest time to fly round-trip from San Francisco to Boulder. Price data was last updated on October 6, 2024.

Travelers seeking maximum savings on their San Francisco to Boulder flight should consider departing on Friday evenings when fares are most often at their lowest. Friday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from San Francisco to Boulder

Explore weekly flight availability from San Francisco 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 March 26, 2025.

The most flights from SFO to BD9 are scheduled on a Wednesday (53 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (1 on average).

Rainfall in Boulder by month

Plan your trip to Boulder by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Boulder ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Boulder when rainfall is around 0.5 in.

Temperature in Boulder by month

Plan your trip to Boulder by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Boulder, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

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 March 26, 2025.
To help decide which airline to fly from San Francisco to Boulder, see what other customers have to say about Southwest, Alaska Airlines and Delta. In addition to providing an overall rating, users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Southwest
8.1
Very good
4,273 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Alaska Airlines
8.0
Very good
9,789 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Delta
8.0
Very good
7,891 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
Hawaiian Airlines
7.9
Good
2,331 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.
United Airlines
7.4
Good
8,608 reviews
Southwest
8.1
Very good
4,273 reviews

Overall

8.1

Boarding

8.2

Comfort

8.1

Entertainment

7.6

Food

7.1

Crew

8.6

Reviews

1 / 20
10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Related info for your journey

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

  • What airport do you fly from for flights from San Francisco to Boulder?

    Located just 11.8 mi from the city center, San Francisco is the airport most travelers will use when flying to Boulder from San Francisco. Booking flights from San Francisco (SFO) to Boulder should be relatively easy as there are 37 daily outbound flights to Boulder from 6 different airlines.

  • How popular is this San Francisco to Boulder flight route?

    This flight path from San Francisco to Boulder was viewed by 330 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • What are the cheapest airlines to fly from San Francisco to Boulder one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $49. Users have also found prices from $71 and $76 on United Airlines and Southwest, respectively.

  • What are the most reliable airlines from San Francisco to Boulder?

    Consider United Airlines (90%), Virgin Australia (90%) or Air New Zealand (90%) when booking your flight. These represent the most reliable airlines when flying from San Francisco to Boulder.

  • What are the cheapest flights from San Francisco to Boulder?

    The cheapest flight price from San Francisco to Boulder is $62. On average you can expect to pay $798. The most popular route, (San Francisco - Denver Intl), can usually be booked for $141.

  • Can I find deals for flights from San Francisco to Boulder that include hotel bookings?

    Yes. In addition to deals on San Francisco to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from San Francisco to Boulder?

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

  • Can I find deals for business class flights from San Francisco to Boulder?

    Yes. Cheapflights offers flight deals from San Francisco 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 San Francisco to Boulder?

    Currently, October is the cheapest month in which you can book a flight from San Francisco to Boulder (average of $197). Flying from San Francisco to Boulder in March is currently the most expensive (average of $278). 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.

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Top 6 airlines flying from San Francisco to Boulder

Discover the top 6 airlines that operate flights from San Francisco 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 March 26, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$58Average$154FlexibilityNo cancel feeOn-time62%
Alaska AirlinesCheapest$116Average$320FlexibilityNo cancel feeOn-time75%
United AirlinesCheapest$156Average$369FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$159Average$326FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$187Average$339FlexibilityNo cancel feeOn-time71%
DeltaCheapest$195Average$336FlexibilityNo cancel feeOn-timeN/A
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