$36+ Cheap flights from San Diego (SAN) 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 4/27. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — DEN
Feb 28 — Mar 71
1 adult, Economy
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Find cheap flights from San Diego 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 Diego to Boulder are usually found in February or December, booked 52 days in advance, depart on a Friday or Thursday and return on a Thursday
Cheap flight deals from San Diego to Boulder
Cheapest flights from San Diego to BoulderExplore the most affordable flight options available from San Diego to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on January 29, 2026.
Explore the most affordable flight options available from San Diego 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.
Tue 3/106:25 am
SAN
- DEN
Nonstop2h 35m
Frontier
Tue 3/1710:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/28![Frontier logo]()
$51
This Flightnetwork 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 Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 2/2812:23 pm
SAN
- DEN
Nonstop2h 33m
Frontier
Sun 3/16:44 am
DEN
- SAN
Nonstop2h 40m
Frontier
Deal found 1/27![Frontier logo]()
$52
This Trip.com deal was found by Cheapflights users on 1/29. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 2/247:11 am
SAN
- DEN
Nonstop2h 31m
Frontier
Thu 2/2610:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/29![Frontier logo]()
$53
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.
Thu 2/266:25 am
SAN
- DEN
Nonstop2h 35m
Frontier
Mon 3/210:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/26![Frontier logo]()
$55
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.
Mon 3/309:18 pm
SAN
- DEN
Nonstop2h 29m
Frontier
Thu 4/26:15 am
DEN
- SAN
Nonstop2h 37m
Frontier
Deal found 1/28![Frontier logo]()
$56
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 2/278:35 am
SAN
- DEN
Nonstop2h 34m
Frontier
Sun 3/16:44 am
DEN
- SAN
Nonstop2h 40m
Frontier
Deal found 1/27![Frontier logo]()
$57
This Trip.com deal was found by Cheapflights users on 1/29. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/127:15 am
SAN
- DEN
Nonstop2h 35m
Frontier
Wed 5/139:30 pm
DEN
- SAN
Nonstop2h 36m
Frontier
Deal found 1/29![Frontier logo]()
$58
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.
Wed 3/186:25 am
SAN
- DEN
Nonstop2h 35m
Frontier
Sun 3/2210:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/27![Frontier logo]()
$61
This Kiwi.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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 2/68:16 pm
SAN
- DEN
Nonstop2h 37m
Frontier
Sat 3/710:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/28![Frontier logo]()
$62
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 2/2611:59 am
SAN
- DEN
Nonstop2h 29m
Frontier
Thu 3/59:30 am
DEN
- SAN
Nonstop2h 44m
Frontier
Deal found 1/28![Frontier logo]()
$67
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.
Mon 3/239:08 pm
SAN
- DEN
Nonstop2h 29m
Frontier
Sat 3/2810:29 pm
DEN
- SAN
Nonstop2h 39m
Frontier
Deal found 1/26![Frontier logo]()
$69
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.
Mon 3/309:18 pm
SAN
- DEN
Nonstop2h 29m
Frontier
Sat 4/410:30 pm
DEN
- SAN
Nonstop2h 32m
Frontier
Deal found 1/27![Frontier logo]()
$70
Find flight deals from San Diego to Boulder
Keep the following information in mind while searching for San Diego 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 | $51 (Frontier) |
One-way from | $36 (Kiwi.com) |
Popular in | June |
Cheapest in | February |
Average price | $156 |
Cheapflights Fare Finder
Customize your flight search to find flights from San Diego 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 San Diego to Boulder that are best for you.
Fly from
San Diego
Fly to
Boulder
Route
Depart
Return
Price
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Tue 4/7
6:25 am-10:05 am
Nonstop2h 40m
Denver Intl
Sat 4/11
10:30 pm-12:02 am
Nonstop2h 32m
$56
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Sun 2/15
6:25 am-10:00 am
Nonstop2h 35m
Denver Intl
Wed 2/18
6:30 am-5:51 pm
1 stop12h 21m
$113
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Fri 3/6
2:16 pm-5:48 pm
Nonstop2h 32m
Denver Intl
Mon 3/9
6:45 pm-8:27 pm
Nonstop2h 42m
$117
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Tue 2/24
6:20 am-9:50 am
Nonstop2h 30m
Denver Intl
Sat 2/28
6:55 am-8:40 am
Nonstop2h 45m
$117
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 4/2
6:32 am-10:09 am
Nonstop2h 37m
Denver Intl
Sun 4/5
7:45 am-9:16 am
Nonstop2h 31m
$117
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Fri 3/6
2:16 pm-5:48 pm
Nonstop2h 32m
Denver Intl
Tue 3/10
1:10 pm-2:49 pm
Nonstop2h 39m
$117
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Fri 4/3
8:42 am-12:20 pm
Nonstop2h 38m
Denver Intl
Fri 4/3
6:20 pm-7:58 pm
Nonstop2h 38m
$147
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Fri 2/13
8:35 am-12:09 pm
Nonstop2h 34m
Denver Intl
Mon 3/16
10:29 pm-12:08 am
Nonstop2h 39m
$156
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 5/14
6:32 am-10:09 am
Nonstop2h 37m
Denver Intl
Thu 5/21
9:00 pm-10:25 pm
Nonstop2h 25m
$183
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 6/11
6:35 am-10:08 am
Nonstop2h 33m
Denver Intl
Fri 6/19
3:49 pm-5:14 pm
Nonstop2h 25m
$195
Showing 1-10 of 24 results
Best time to book a flight from San Diego to Boulder
Have a flexible travel schedule? Discover the best time to fly to Boulder from San Diego 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 Diego to Boulder
How far ahead should I book a flight from San Diego to Boulder?
Use this chart to determine the optimal time to book a round-trip flight from San Diego to Boulder. Price data was last updated on January 23, 2026.
Booking 23 days in advance of your planned departure date is, on average, the best time to get cheap flights from San Diego 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 Diego to Boulder?
Currently, January is the cheapest month in which you can book a flight from San Diego to Boulder (average of $38). Flying from San Diego to Boulder in May is currently the most expensive (average of $70). 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 SAN to BD9?
Find hourly flight availability from San Diego 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 San Diego to Boulder in the evening. If you’re flexible enough to do this you can expect to save up to 38% on your trip compared to booking a flight at noon.
What is the cheapest day to fly from San Diego to Boulder?
Use this chart to determine the cheapest time to fly round-trip from San Diego to Boulder. Price data was last updated on January 24, 2026.
Travelers seeking maximum savings on their San Diego to Boulder flight should consider departing on Tuesday at noon 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 Diego to Boulder
Explore weekly flight availability from San Diego 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 SAN to BD9 are scheduled on a Wednesday (27 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (12 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 29, 2026.
See what other customers who have flown with Alaska Airlines, Southwest, and Hawaiian Airlines from San Diego to Boulder have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Overall
8.0
Entertainment
7.0
Food
7.1
Crew
8.5
Boarding
8.1
Comfort
7.8
Reviews
1 / 20
10.0
ExcellentAnonymous,Jan 2026
STS - LAX
Related info for your journey
Find useful and relevant information for your journey from San Diego 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 Diego to Boulder
See prices for flight routes from nearby airports that may be better suited for you.
Top 6 airlines flying from San Diego to Boulder
Discover the top 6 airlines that operate flights from San Diego 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.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$55 | Average$156 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$68 | Average$167 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$102 | Average$189 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$117 | Average$305 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$131 | Average$335 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$218 | Average$380 | FlexibilityNo cancel fee | On-time71% |