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$66+ 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 5/7. Fares are subject to change and may not be available on all flights or dates of travel.
SFO — DEN
may. 5 — may. 121
lun. 5/5
lun. 5/12
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 24 days in advance, depart on a Wednesday or Friday 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 abril 30, 2025.

Most accurate provider

CheapOair
3 stars

Most trusted provider

CheapOair
3 stars

Round-trip from

$106
(FlightHub)

One-way from

$66
(Cheapflightsfares)

Popular in

December

Cheapest in

September

Average price

$208
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
Search Deals
Highest demand for flights based on searches. 4% potential increase in price ($10 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 April 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 abril 30, 2025.

This FlightHub deal was found by Cheapflights users on 4/28. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 8/66:37 amSFO - DEN
Nonstop2h 40mFrontier
dom. 8/1010:29 pmDEN - SFO
Nonstop2h 50mFrontier
Deal found 4/28$104
This Orbitz deal was found by Cheapflights users on 4/29. 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.
dom. 6/296:37 amSFO - DEN
Nonstop2h 35mMultiple Airlines
mar. 7/16:00 amDEN - SFO
1 stop8h 45mMultiple Airlines
Deal found 4/29$171
This United Airlines deal was found by Cheapflights users on 4/29. 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.
mar. 6/108:45 pmSFO - DEN
Nonstop2h 33mUnited Airlines
sáb. 6/148:02 amDEN - SFO
Nonstop2h 43mUnited Airlines
Deal found 4/29$197
This Southwest deal was found by Cheapflights users on 4/29. 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.
mar. 6/105:55 pmSFO - DEN
Nonstop2h 25mSouthwest
jue. 6/128:10 pmDEN - SFO
Nonstop2h 40mSouthwest
Deal found 4/29$217
This Alaska Airlines deal was found by Cheapflights users on 4/29. 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.
mar. 5/2711:49 amSFO - DEN
1 stop5h 20mAlaska Airlines
mar. 6/311:40 amDEN - SFO
2 stops8h 42mAlaska Airlines
Deal found 4/29$246
This Delta deal was found by Cheapflights users on 4/29. 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.
jue. 7/105:08 pmSFO - DEN
1 stop4h 13mDelta
dom. 7/136:05 amDEN - SFO
1 stop4h 55mDelta
Deal found 4/29$257

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 abril 30, 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

sáb. 6/7

6:37 am-10:12 am

Nonstop2h 35m

Denver Intl

jue. 6/12

10:29 pm-12:24 am

Nonstop2h 55m

$106

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

dom. 6/29

6:37 am-10:12 am

Nonstop2h 35m

Denver Intl

mar. 7/1

6:00 am-1:45 pm

1 stop8h 45m

$171

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mar. 6/10

8:45 pm-12:18 am

Nonstop2h 33m

Denver Intl

sáb. 6/14

8:02 am-9:45 am

Nonstop2h 43m

$197

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mar. 6/10

5:55 pm-9:20 pm

Nonstop2h 25m

Denver Intl

jue. 6/12

8:10 pm-9:50 pm

Nonstop2h 40m

$217

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mar. 5/27

11:49 am-6:09 pm

1 stop5h 20m

Denver Intl

mar. 6/3

11:40 am-7:22 pm

2 stops8h 42m

$246

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

jue. 7/10

5:08 pm-10:21 pm

1 stop4h 13m

Denver Intl

dom. 7/13

6:05 am-10:00 am

1 stop4h 55m

$257

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mar. 5/20

6:00 am-9:35 am

Nonstop2h 35m

$71

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mié. 5/14

6:35 am-10:14 am

Nonstop2h 39m

$72

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

jue. 5/22

11:26 am-7:49 pm

1 stop7h 23m

$100

San FranciscoDenver

SFO - DEN

SFODEN

San Francisco

mar. 5/20

9:25 am-4:49 pm

1 stop6h 24m

$101

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/29

Showing 1-10 of 14 results
1
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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 April 25, 2025.

Booking 24 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 abril 30, 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. Sunday 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 abril 30, 2025.

The most flights from SFO to BD9 are scheduled on a Tuesday (49 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (4 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 abril 30, 2025.
To help decide which airline to fly from San Francisco to Boulder, see what other customers have to say about Alaska Airlines, Southwest 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.
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
9,961 reviews
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,295 reviews
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,936 reviews
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Hawaiian Airlines
7.9
Good
2,406 reviews
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,696 reviews
Alaska Airlines
8.0
Very good
9,961 reviews

Entertainment

7.1

Comfort

7.9

Food

7.1

Boarding

8.2

Overall

8.0

Crew

8.5

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

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 21 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 322 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 $66. Users have also found prices from $81 and $90 on Southwest and United Airlines, respectively.

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

    Consider Frontier (94%), Air Canada (90%) or United Airlines (89%) 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 $79. On average you can expect to pay $850. The most popular route, (San Francisco - Denver Intl), can usually be booked for $95.

  • 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.

See more FAQs

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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 abril 30, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$59Average$157FlexibilityNo cancel feeOn-time62%
Alaska AirlinesCheapest$116Average$320FlexibilityNo cancel feeOn-time75%
SouthwestCheapest$146Average$326FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$157Average$383FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$182Average$319FlexibilityNo cancel feeOn-time71%
DeltaCheapest$196Average$296FlexibilityNo cancel feeOn-timeN/A

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