$115+ 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 10/16. Fares are subject to change and may not be available on all flights or dates of travel.
SFO — DEN
Sep 5 — Sep 121
Round-trip
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
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.3. Compare prices and book
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 October, booked 71 days in advance, depart on a Wednesday or Saturday and return on a Friday
Cheap flight deals from San Francisco to Boulder
Cheapest
Best
Last-minute
One-way
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 August 6, 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 August 6, 2026.
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 9/181:10 pm -
1 stop19h 33m
Mon 9/211:10 pm -
1 stop9h 17m
Deal found 8/4![Frontier logo]()
$205
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Thu 8/271:07 pm -
1 stop29h 13m
Sun 8/3010:29 pm -
Nonstop2h 49m
Deal found 8/3![Frontier logo]()
$206
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 9/410:35 pm -
1 stop9h 44m
Fri 9/117:06 pm -
1 stop16h 16m
Deal found 8/4![Frontier logo]()
$207
This Frontier deal was found by Cheapflights users on 8/3. 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.
Fri 10/29:00 am -
1 stop7h 59m
Sun 11/1510:29 pm -
Nonstop2h 46m
Deal found 8/3![Frontier logo]()
$208
This Super.com deal was found by Cheapflights users on 8/4. 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 9/46:00 am -
Nonstop2h 41m
Sun 9/610:29 pm -
Nonstop2h 49m
Deal found 8/4![Frontier logo]()
$209
This Frontier deal was found by Cheapflights users on 8/1. 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.
Tue 8/258:56 pm -
1 stop5h 52m
Sun 8/3010:29 pm -
Nonstop2h 49m
Deal found 8/1![Frontier logo]()
$210
This Cheapflightsfares deal was found by Cheapflights users on 8/1. 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 8/207:30 pm -
Nonstop2h 40m
Sat 8/222:55 pm -
1 stop8h 59m
Deal found 8/1![Frontier logo]()
$211
This Frontier deal was found by Cheapflights users on 8/1. 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 8/207:30 pm -
Nonstop2h 40m
Wed 8/2610:00 am -
1 stop10h 56m
Deal found 8/1![Frontier logo]()
$213
This Cheapflightsfares deal was found by Cheapflights users on 8/4. 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 9/310:59 pm -
1 stop11h 20m
Tue 9/810:29 pm -
Nonstop2h 49m
Deal found 8/4![Frontier logo]()
$215
This Kiwi.com deal was found by Cheapflights users on 8/1. 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 8/146:04 pm -
Nonstop2h 45m
Sun 8/236:00 am -
1 stop13h 09m
Deal found 8/1![Frontier logo]()
$216
Best flights from San Francisco to BoulderDiscover carefully curated flight deals from San Francisco to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 6, 2026.
Discover carefully curated flight deals from San Francisco to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated August 6, 2026.
This Alaska Airlines deal was found by Cheapflights users on 8/2. 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.
Sun 9/137:08 am -
1 stop15h 36m
Tue 9/151:43 pm -
1 stop10h 29m
Deal found 8/2![Alaska Airlines logo]()
$243
This Southwest deal was found by Cheapflights users on 8/5. 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.
Tue 10/271:25 pm -
Nonstop2h 30m
Mon 11/27:15 pm -
2 stops5h 50m
Deal found 8/5![Southwest logo]()
$290
This Delta deal was found by Cheapflights users on 8/5. 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.
Thu 8/2711:54 am -
1 stop5h 24m
Sat 8/2912:54 pm -
2 stops12h 05m
Deal found 8/5![Delta logo]()
$348
This Southwest deal was found by Cheapflights users on 8/3. 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.
Wed 9/25:50 am -
2 stops7h 10m
Sun 9/68:55 am -
1 stop7h 05m
Deal found 8/3![Southwest logo]()
$293
This Alaska Airlines deal was found by Cheapflights users on 8/5. 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.
Wed 8/2610:59 am -
2 stops9h 14m
Sat 8/291:43 pm -
1 stop6h 23m
Deal found 8/5![Alaska Airlines logo]()
$330
This Southwest deal was found by Cheapflights users on 8/1. 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.
Thu 9/1010:50 am -
1 stop6h 25m
Tue 9/1512:35 pm -
2 stops7h 40m
Deal found 8/1![Southwest logo]()
$304
This Southwest deal was found by Cheapflights users on 8/3. 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.
Mon 8/314:00 pm -
1 stop6h 10m
Sat 9/199:20 am -
2 stops9h 35m
Deal found 8/3![Southwest logo]()
$304
This Southwest deal was found by Cheapflights users on 8/2. 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.
Sat 9/265:00 am -
2 stops6h 35m
Mon 10/55:55 am -
2 stops6h 25m
Deal found 8/2![Southwest logo]()
$309
This Southwest deal was found by Cheapflights users on 8/1. 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.
Thu 8/276:45 am -
2 stops6h 45m
Sat 8/299:20 am -
2 stops9h 25m
Deal found 8/1![Southwest logo]()
$309
This Southwest deal was found by Cheapflights users on 8/3. 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.
Thu 9/35:10 am -
1 stop5h 35m
Thu 9/103:10 pm -
2 stops6h 25m
Deal found 8/3![Southwest logo]()
$348
This Southwest deal was found by Cheapflights users on 8/3. 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.
Thu 9/105:10 am -
1 stop5h 35m
Fri 9/183:10 pm -
2 stops6h 25m
Deal found 8/3![Southwest logo]()
$349
This Southwest deal was found by Cheapflights users on 8/3. 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.
Fri 9/2511:55 am -
2 stops6h 20m
Mon 9/285:20 pm -
1 stop5h 25m
Deal found 8/3![Southwest logo]()
$353
Last-minute flights from San Francisco to BoulderDiscover last-minute flight deals from San Francisco to Boulder. Data last updated August 6, 2026 and is based on user searches.
Discover last-minute flight deals from San Francisco to Boulder. Data last updated August 6, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 8/3. 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.
Tue 8/116:00 am -
Nonstop2h 41m
Tue 8/1810:29 pm -
Nonstop2h 49m
Deal found 8/3![Frontier logo]()
$208
This Kiwi.com deal was found by Cheapflights users on 8/1. 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 8/146:04 pm -
Nonstop2h 45m
Sun 8/236:00 am -
1 stop13h 09m
Deal found 8/1![Frontier logo]()
$216
This Cheapflightsfares deal was found by Cheapflights users on 8/1. 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 8/207:30 pm -
Nonstop2h 40m
Sat 8/222:55 pm -
1 stop8h 59m
Deal found 8/1![Frontier logo]()
$211
This Frontier deal was found by Cheapflights users on 8/1. 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 8/207:30 pm -
Nonstop2h 40m
Wed 8/2610:00 am -
1 stop10h 56m
Deal found 8/1![Frontier logo]()
$213
This Frontier deal was found by Cheapflights users on 8/1. 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.
Tue 8/258:56 pm -
1 stop5h 52m
Sun 8/3010:29 pm -
Nonstop2h 49m
Deal found 8/1![Frontier logo]()
$210
This Kiwi.com deal was found by Cheapflights users on 8/3. 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.
Thu 8/271:07 pm -
1 stop29h 13m
Sun 8/3010:29 pm -
Nonstop2h 49m
Deal found 8/3![Frontier logo]()
$206
This Cheapflightsfares deal was found by Cheapflights users on 8/4. 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 9/310:59 pm -
1 stop11h 20m
Tue 9/810:29 pm -
Nonstop2h 49m
Deal found 8/4![Frontier logo]()
$215
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 9/410:35 pm -
1 stop9h 44m
Fri 9/117:06 pm -
1 stop16h 16m
Deal found 8/4![Frontier logo]()
$207
This Super.com deal was found by Cheapflights users on 8/4. 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 9/46:00 am -
Nonstop2h 41m
Sun 9/610:29 pm -
Nonstop2h 49m
Deal found 8/4![Frontier logo]()
$209
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 9/181:10 pm -
1 stop19h 33m
Mon 9/211:10 pm -
1 stop9h 17m
Deal found 8/4![Frontier logo]()
$205
One-way flights from San Francisco to BoulderSearch for one-way flight options from San Francisco to Boulder. Find affordable one-way fares based on user searches. Data last updated August 6, 2026.
Search for one-way flight options from San Francisco to Boulder. Find affordable one-way fares based on user searches. Data last updated August 6, 2026.
This Kiwi.com deal was found by Cheapflights users on 8/3. 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 10/166:22 am -
2 stops13h 04m
Deal found 8/3![Frontier logo]()
$115
This Kiwi.com deal was found by Cheapflights users on 8/2. 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 9/129:00 am -
2 stops13h 44m
Deal found 8/2![Frontier logo]()
$116
This Alaska Airlines deal was found by Cheapflights users on 8/3. 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.
Fri 8/285:16 pm -
1 stop18h 04m
Deal found 8/3![Alaska Airlines logo]()
$117
This Kiwi.com deal was found by Cheapflights users on 8/3. 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 10/410:24 pm -
2 stops24h 24m
Deal found 8/3![Frontier logo]()
$118
This Kiwi.com deal was found by Cheapflights users on 8/4. 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 10/236:22 am -
1 stop10h 21m
Deal found 8/4![Frontier logo]()
$119
This Kiwi.com deal was found by Cheapflights users on 8/2. 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 8/238:56 pm -
2 stops16h 14m
Deal found 8/2![Frontier logo]()
$122
This Kiwi.com deal was found by Cheapflights users on 8/1. 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.
Wed 9/167:11 pm -
2 stops12h 04m
Deal found 8/1![Frontier logo]()
$123
This Super.com deal was found by Cheapflights users on 8/3. 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 9/46:00 am -
Nonstop2h 41m
Deal found 8/3![Frontier logo]()
$126
This Kiwi.com deal was found by Cheapflights users on 8/4. 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.
Wed 9/239:00 am -
2 stops13h 44m
Deal found 8/4![Frontier logo]()
$127
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 August 6, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $205 (Kiwi.com) |
One-way from | $115 (Kiwi.com) |
Popular in | June |
Cheapest in | February |
Average price | $278 |
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 August 6, 2026.
Use the filters below to find and compare flights from San Francisco to Boulder that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Sun 9/13
7:08 am-11:44 pm
1 stop15h 36m
Denver Intl
Tue 9/15
1:43 pm-11:12 pm
1 stop10h 29m
$243
Quickest round-trip
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Tue 10/27
1:25 pm-4:55 pm
Nonstop2h 30m
Denver Intl
Mon 11/2
7:15 pm-12:05 am
2 stops5h 50m
$290
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Wed 9/2
5:50 am-2:00 pm
2 stops7h 10m
Denver Intl
Sun 9/6
8:55 am-3:00 pm
1 stop7h 05m
$293
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Thu 9/10
10:50 am-6:15 pm
1 stop6h 25m
Denver Intl
Tue 9/15
12:35 pm-7:15 pm
2 stops7h 40m
$304
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Mon 8/31
4:00 pm-11:10 pm
1 stop6h 10m
Denver Intl
Sat 9/19
9:20 am-5:55 pm
2 stops9h 35m
$304
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Sat 9/26
5:00 am-12:35 pm
2 stops6h 35m
Denver Intl
Mon 10/5
5:55 am-11:20 am
2 stops6h 25m
$309
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Thu 8/27
6:45 am-2:30 pm
2 stops6h 45m
Denver Intl
Sat 8/29
9:20 am-5:45 pm
2 stops9h 25m
$309
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Wed 8/26
10:59 am-9:13 pm
2 stops9h 14m
Denver Intl
Sat 8/29
1:43 pm-7:06 pm
1 stop6h 23m
$330
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Thu 8/27
11:54 am-6:18 pm
1 stop5h 24m
Denver Intl
Sat 8/29
12:54 pm-11:59 pm
2 stops12h 05m
$348
San FranciscoDenver
SFO San Francisco - DEN Denver Intl
SFODEN
San Francisco
Thu 9/3
5:10 am-11:45 am
1 stop5h 35m
Denver Intl
Thu 9/10
3:10 pm-8:35 pm
2 stops6h 25m
$348
Showing 1-10 of 24 resultsSorted by cheapest first
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.
SFO-DEN
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
SFO-BD9
SFO-DEN
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 August 6, 2026.
It’s typically best to fly out from San Francisco to Boulder in the evening. Doing so could potentially save you 27% on the flight price compared to flying at noon, which is usually more expensive.
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 August 6, 2026.
The most flights from SFO to BD9 are scheduled on a Wednesday (63 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (7 on average).
How much does it cost to fly round-trip from San Francisco to Boulder?
Airfare is below average for this route at the moment.
San Francisco to Boulder flights typically cost between $207 and $385 in September.The cheapest round-trip price found within the last 5 days was $205 on Frontier (Sep 18-Sep 21).
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 August 1, 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.
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 August 6, 2026.
Peruse reviews from past customers who have flown with Southwest,United Airlines, andJetBlue 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.
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Food
7.0
Overall
8.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
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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
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San Francisco and Boulder flights
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San Francisco to Boulder flights
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Top 5 airlines flying from San Francisco to Boulder
Discover the top 5 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 August 6, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$83 | Average$239 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$174 | Average$408 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$188 | Average$383 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$196 | Average$416 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$252 | Average$393 | FlexibilityNo cancel fee | On-time62% |