$51+ 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 3/3. Fares are subject to change and may not be available on all flights or dates of travel.
SFO — DEN
Feb 27 — Mar 61
1 adult, Economy
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Find cheap flights from San Francisco to Boulder with Cheapflights
1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”2. Select your favorite providers
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Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.Cheapflights Tip: The best prices from San Francisco to Boulder are usually found in February or March, booked 61 days in advance, depart on a Friday or Wednesday and return on a Friday
Cheap flight deals from San Francisco to Boulder
Cheapest flights from San Francisco to BoulderExplore 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 January 28, 2026.
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 January 28, 2026.
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.
Mon 3/28:18 pm
SFO
- DEN
1 stop10h 36m
Frontier
Wed 3/410:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/27![Frontier logo]()
$86
This Super.com 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 2/266:15 am
SFO
- DEN
Nonstop2h 47m
Frontier
Sun 3/16:00 am
DEN
- SFO
Nonstop3h 03m
Frontier
Deal found 1/28![Frontier logo]()
$87
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.
Thu 3/58:48 am
SFO
- DEN
Nonstop2h 40m
Frontier
Sun 3/810:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/27![Frontier logo]()
$88
This Kiwi.com deal was found by Cheapflights users on 1/26. 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.
Sun 2/226:15 am
SFO
- DEN
Nonstop2h 47m
Frontier
Sat 2/2810:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/26![Frontier logo]()
$91
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.
Tue 2/247:15 pm
SFO
- DEN
1 stop7h 41m
Frontier
Sat 2/2810:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/27![Frontier logo]()
$92
This WAYA deal was found by Cheapflights users on 1/26. 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 WAYA is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 3/99:24 pm
SFO
- DEN
1 stop5h 32m
Frontier
Tue 3/106:11 pm
DEN
- SFO
Nonstop2h 58m
Frontier
Deal found 1/26![Frontier logo]()
$93
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.
Tue 2/246:55 am
SFO
- DEN
Nonstop2h 47m
Frontier
Mon 3/26:00 am
DEN
- SFO
Nonstop3h 03m
Frontier
Deal found 1/27![Frontier logo]()
$96
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.
Wed 2/186:55 am
SFO
- DEN
Nonstop2h 47m
Frontier
Sat 2/2810:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/27![Frontier logo]()
$97
This Frontier deal was found by Cheapflights users on 1/26. 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.
Sun 2/158:48 am
SFO
- DEN
Nonstop2h 40m
Frontier
Tue 2/248:00 pm
DEN
- SFO
Nonstop3h 01m
Frontier
Deal found 1/26![Frontier logo]()
$98
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.
Sat 2/286:15 am
SFO
- DEN
Nonstop2h 47m
Frontier
Mon 3/210:34 pm
DEN
- SFO
1 stop20h 46m
Frontier
Deal found 1/27![Frontier logo]()
$99
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.
Thu 2/268:05 am
SFO
- DEN
1 stop6h 11m
Frontier
Tue 3/38:00 pm
DEN
- SFO
Nonstop3h 01m
Frontier
Deal found 1/27![Frontier logo]()
$101
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 2/186:55 am
SFO
- DEN
Nonstop2h 47m
Frontier
Wed 2/2510:29 pm
DEN
- SFO
Nonstop2h 59m
Frontier
Deal found 1/28![Frontier logo]()
$102
Find 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 January 28, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $86 (Kiwi.com) |
One-way from | $51 (WAYA) |
Popular in | December |
Cheapest in | February |
Average price | $237 |
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 January 28, 2026.
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 2/25
12:30 pm-4:00 pm
Nonstop2h 30m
Denver Intl
Sat 2/28
8:10 am-10:05 am
Nonstop2h 55m
$177
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Sat 2/28
4:02 pm-10:37 pm
1 stop5h 35m
Denver Intl
Tue 3/3
6:20 pm-11:54 pm
1 stop6h 34m
$197
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Thu 2/19
8:11 am-11:59 pm
1 stop14h 48m
Denver Intl
Tue 2/24
6:45 pm-11:59 pm
1 stop6h 14m
$219
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Mon 3/16
6:30 am-5:20 pm
1 stop9h 50m
Denver Intl
Wed 3/18
1:16 pm-10:52 pm
1 stop10h 36m
$223
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Wed 4/1
7:20 pm-10:50 pm
Nonstop2h 30m
Denver Intl
Sun 4/5
7:00 pm-12:55 am
1 stop6h 55m
$227
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Fri 3/13
2:58 pm-10:42 am
1 stop18h 44m
Denver Intl
Tue 3/17
6:45 pm-11:59 pm
1 stop6h 14m
$230
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Tue 2/17
5:50 am-9:20 am
Nonstop2h 30m
Denver Intl
Sat 2/21
12:45 pm-8:15 pm
1 stop8h 30m
$233
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Wed 3/25
5:01 pm-10:31 pm
1 stop4h 30m
Denver Intl
Thu 3/26
6:10 pm-11:00 pm
1 stop5h 50m
$237
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Sat 2/28
5:00 am-1:20 pm
2 stops7h 20m
Denver Intl
Mon 3/2
9:35 am-2:10 pm
1 stop5h 35m
$242
San FranciscoDenver
SFO - DEN
SFODEN
San Francisco
Fri 2/20
5:55 am-5:27 pm
1 stop10h 32m
Denver Intl
Sat 2/21
6:40 am-10:41 pm
1 stop17h 01m
$243
Showing 1-10 of 24 results
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 January 23, 2026.
Booking 61 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, February is the cheapest month in which you can book a flight from San Francisco to Boulder (average of $28). Flying from San Francisco to Boulder in June is currently the most expensive (average of $106). 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 January 28, 2026.
It’s typically best to fly out from San Francisco to Boulder in the evening. Doing so could potentially save you 31% on the flight price compared to flying at noon, which is usually more expensive.
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 January 24, 2026.
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 January 28, 2026.
The most flights from SFO to BD9 are scheduled on a Monday (46 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (33 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 January 28, 2026.
Peruse reviews from past customers who have flown with Southwest, United Airlines, and American Airlines from San Francisco to Boulder to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Overall
8.0
Food
7.0
Comfort
8.0
Crew
8.6
Boarding
8.1
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
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.
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Alternative routes for San Francisco to Boulder
See prices for flight routes from nearby airports that may be better suited for you.
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 January 28, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$64 | Average$189 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$88 | Average$100 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$128 | Average$274 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$156 | Average$382 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$157 | Average$350 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$176 | Average$478 | FlexibilityNo cancel fee | On-time71% |