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$68+ 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 11/8. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — DEN
ago. 23 — ago. 301
sáb. 8/23
sáb. 8/30
1 adult, Economy
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Cheapflights Tip: The best prices from San Diego to Boulder are usually found in January or February, booked 39 days in advance, depart on a Saturday or Friday and return on a Tuesday

Cheap 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 agosto 18, 2025.

Round-trip from

$98
(Booking.com)

One-way from

$68
(Southwest)

Popular in

March

Cheapest in

January

Average price

$184
From San Diego to Boulder
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One-way flight from San Diego to Boulder
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Highest demand for flights based on searches. 3% potential increase in price ($8 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in August 2025
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Find flight deals from San Diego to Boulder

Cheapest flights from San Diego to Boulder
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 agosto 18, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 8/18. 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.
vie. 9/1210:20 amSAN - DEN
Nonstop2h 39mFrontier
dom. 9/1410:29 pmDEN - SAN
Nonstop2h 24mFrontier
Deal found 8/18$98
This FlightHub deal was found by Cheapflights users on 8/16. 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.
vie. 9/1910:20 amSAN - DEN
Nonstop2h 39mFrontier
dom. 9/219:38 amDEN - SAN
Nonstop2h 31mFrontier
Deal found 8/16$103
This Mytrip deal was found by Cheapflights users on 8/16. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 9/36:25 amSAN - DEN
Nonstop2h 37mFrontier
lun. 9/810:29 pmDEN - SAN
1 stop23h 55mFrontier
Deal found 8/16$104
This Booking.com deal was found by Cheapflights users on 8/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 9/277:15 amSAN - DEN
Nonstop2h 35mFrontier
dom. 9/286:30 amDEN - SAN
1 stop9h 40mFrontier
Deal found 8/16$105
This Frontier deal was found by Cheapflights users on 8/16. 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.
dom. 8/316:29 amSAN - DEN
Nonstop2h 37mFrontier
jue. 9/410:29 pmDEN - SAN
Nonstop2h 24mFrontier
Deal found 8/16$106
This Frontier deal was found by Cheapflights users on 8/17. 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.
vie. 10/109:03 pmSAN - DEN
Nonstop2h 43mFrontier
dom. 10/128:30 amDEN - SAN
Nonstop2h 27mFrontier
Deal found 8/17$108
This Mytrip deal was found by Cheapflights users on 8/17. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mié. 9/178:00 amSAN - DEN
1 stop6h 49mFrontier
mar. 9/238:50 pmDEN - SAN
Nonstop2h 34mFrontier
Deal found 8/17$110
This Mytrip deal was found by Cheapflights users on 8/17. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
sáb. 9/277:15 amSAN - DEN
Nonstop2h 35mFrontier
lun. 9/297:17 pmDEN - SAN
1 stop5h 00mFrontier
Deal found 8/17$111
This Booking.com deal was found by Cheapflights users on 8/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
jue. 9/189:03 pmSAN - DEN
Nonstop2h 35mFrontier
dom. 9/216:00 amDEN - SAN
1 stop4h 25mFrontier
Deal found 8/16$112
This Cheapflightsfares deal was found by Cheapflights users on 8/17. 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.
lun. 9/226:35 amSAN - DEN
Nonstop2h 33mFrontier
lun. 9/296:00 amDEN - SAN
1 stop4h 25mFrontier
Deal found 8/17$114
This Trip.com deal was found by Cheapflights users on 8/16. 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.
lun. 11/175:47 pmSAN - DEN
Nonstop2h 31mMultiple Airlines
sáb. 11/227:20 pmDEN - SAN
Nonstop2h 40mMultiple Airlines
Deal found 8/16$115

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 agosto 18, 2025.
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

sáb. 9/27

7:15 am-10:50 am

Nonstop2h 35m

Denver Intl

lun. 9/29

7:00 am-11:48 am

1 stop5h 48m

$104

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 9/23

10:16 am-3:44 pm

1 stop4h 28m

Denver Intl

sáb. 9/27

8:50 pm-10:24 pm

Nonstop2h 34m

$104

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mié. 9/3

6:25 am-10:02 am

Nonstop2h 37m

Denver Intl

lun. 9/8

10:29 pm-9:24 pm

1 stop23h 55m

$104

San DiegoDenver

SAN - DEN

SANDEN

San Diego

sáb. 10/11

8:00 am-7:38 pm

1 stop10h 38m

Denver Intl

mar. 10/14

10:29 pm-11:50 pm

Nonstop2h 21m

$104

San DiegoDenver

SAN - DEN

SANDEN

San Diego

sáb. 9/27

7:15 am-10:50 am

Nonstop2h 35m

Denver Intl

dom. 9/28

6:30 am-3:10 pm

1 stop9h 40m

$105

San DiegoDenver

SAN - DEN

SANDEN

San Diego

dom. 8/31

6:29 am-10:06 am

Nonstop2h 37m

Denver Intl

jue. 9/4

10:29 pm-11:53 pm

Nonstop2h 24m

$106

San DiegoDenver

SAN - DEN

SANDEN

San Diego

jue. 10/9

6:41 am-10:18 am

Nonstop2h 37m

Denver Intl

dom. 10/12

8:30 am-9:57 am

Nonstop2h 27m

$108

San DiegoDenver

SAN - DEN

SANDEN

San Diego

vie. 10/10

1:06 pm-4:50 pm

Nonstop2h 44m

Denver Intl

dom. 10/12

8:30 am-9:57 am

Nonstop2h 27m

$108

San DiegoDenver

SAN - DEN

SANDEN

San Diego

mar. 9/23

7:15 am-10:50 am

Nonstop2h 35m

Denver Intl

mar. 9/30

10:01 am-9:24 pm

1 stop12h 23m

$110

San DiegoDenver

SAN - DEN

SANDEN

San Diego

sáb. 10/18

7:00 am-10:37 am

Nonstop2h 37m

Denver Intl

sáb. 10/18

2:20 pm-8:51 pm

1 stop7h 31m

$110

Flights are sorted by cheapest round-trip flights first.

Deals found on 8/18

Showing 1-10 of 21 results
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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 August 8, 2025.

Booking 39 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, October is the cheapest month in which you can book a flight from San Diego to Boulder (average of $197). Flying from San Diego 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 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 agosto 18, 2025.

When flying from San Diego to Boulder, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

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 December 16, 2024.

Travelers seeking maximum savings on their San Diego to Boulder flight should consider departing on Saturday evenings when fares are most often at their lowest. Monday afternoons 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 agosto 18, 2025.

The most flights from SAN to BD9 are scheduled on a Monday (30 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (1 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 agosto 18, 2025.
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.
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

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
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

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
4,246 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Hawaiian Airlines
7.8
Good
2,664 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

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
8,925 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Frontier
5.8
Fair
3,212 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Crew

8.5

Boarding

8.1

Comfort

7.8

Food

7.1

Overall

8.0

Entertainment

7.0

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 Diego 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 Diego to Boulder?

    San Diego (SAN), located 2.6 mi from the city center, is the airport you fly out of when you book flights from San Diego to Boulder. 7 airlines have flights from San Diego to Boulder on a regular basis. Booking flights from San Diego to Boulder should not be difficult; the airport handles an average of 13 outbound flights to Boulder per day.

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

    Flights from San Diego to Boulder have been viewed 167 times in the past calendar month.

  • How long is the flight from San Diego to Boulder?

    There are many flights that can get you from San Diego to Boulder in 2h 35m. Fly via Frontier to get the fastest option. There are 852 mi between San Diego and Boulder. Most flights are nonstop.

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

    No one likes to see their flight delayed. When booking a flight from San Diego to Boulder consider choosing United Airlines (77%), Air Canada (74%) or SWISS (72%) as they are the most reliable in getting you off to your destination on time.

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

    On average you can expect to pay $767 for a flight from San Diego to Boulder. The cheapest flight overall is $77 while the most popular route, (San Diego - Denver Intl) is currently priced at $95.

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

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

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

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

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

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

    Currently, October is the cheapest month in which you can book a flight from San Diego to Boulder (average of $197). Flying from San Diego 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 7 airlines flying from San Diego to Boulder

Discover the top 7 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 agosto 18, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$66Average$160FlexibilityNo cancel feeOn-time62%
Hawaiian AirlinesCheapest$98Average$232FlexibilityNo cancel feeOn-time85%
Alaska AirlinesCheapest$137Average$217FlexibilityNo cancel feeOn-time75%
SouthwestCheapest$157Average$328FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$167Average$343FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$197Average$326FlexibilityNo cancel feeOn-time71%
DeltaCheapest$206Average$306FlexibilityNo cancel feeOn-timeN/A

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