$54+ 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 5/23. Fares are subject to change and may not be available on all flights or dates of travel.
SAN — DEN
Apr 16 — Apr 231
Round-trip
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 39 days in advance, depart on a Friday or Thursday and return on a Thursday
Cheap flight deals from San Diego to Boulder
Cheapest
Best
Last-minute
One-way
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 March 17, 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 March 17, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/14. 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 5/156:25 am
SAN
- DEN
Nonstop2h 36m
Frontier
Sat 5/167:12 am
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/14![Frontier logo]()
$63
This Super.com deal was found by Cheapflights users on 3/16. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sun 4/267:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/16![Frontier logo]()
$67
This Flightnetwork deal was found by Cheapflights users on 3/14. 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.
Wed 4/2210:30 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sun 4/267:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/14![Frontier logo]()
$69
This Super.com deal was found by Cheapflights users on 3/12. 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 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sat 4/256:30 pm
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/12![Frontier logo]()
$71
This Cheapflightsfares deal was found by Cheapflights users on 3/13. 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 5/86:25 am
SAN
- DEN
Nonstop2h 36m
Frontier
Sun 5/107:12 am
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/13![Frontier logo]()
$72
This Frontier deal was found by Cheapflights users on 3/14. 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 5/126:25 am
SAN
- DEN
Nonstop2h 36m
Frontier
Sun 5/177:12 am
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/14![Frontier logo]()
$80
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/712:00 pm
SAN
- DEN
Nonstop2h 34m
Frontier
Thu 4/96:15 am
DEN
- SAN
Nonstop2h 37m
Frontier
Deal found 3/13![Frontier logo]()
$81
This Frontier deal was found by Cheapflights users on 3/16. 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.
Thu 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Mon 4/2710:29 pm
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/16![Frontier logo]()
$82
This Expedia deal was found by Cheapflights users on 3/15. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/171:48 pm
SAN
- DEN
Nonstop2h 36m
Multiple Airlines
Sun 4/197:00 am
DEN
- SAN
Nonstop2h 34m
Multiple Airlines
Deal found 3/15![Multiple Airlines logo]()
$87
This Super.com deal was found by Cheapflights users on 3/13. 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 4/306:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Mon 5/47:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/13![Frontier logo]()
$91
This Gotogate deal was found by Cheapflights users on 3/16. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/306:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Thu 5/77:12 am
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/16![Frontier logo]()
$92
Best flights from San Diego to BoulderDiscover carefully curated flight deals from San Diego to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 17, 2026.
Discover carefully curated flight deals from San Diego to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 17, 2026.
This Southwest deal was found by Cheapflights users on 3/11. 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 4/17:45 pm
SAN
- DEN
1 stop4h 00m
Southwest
Sat 4/45:25 am
DEN
- SAN
Nonstop2h 40m
Southwest
Deal found 3/11![Southwest logo]()
$123
This United Airlines deal was found by Cheapflights users on 3/12. 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.
Fri 4/36:32 am
SAN
- DEN
Nonstop2h 37m
United Airlines
Sun 4/57:45 am
DEN
- SAN
Nonstop2h 31m
United Airlines
Deal found 3/12![United Airlines logo]()
$146
This Delta deal was found by Cheapflights users on 3/12. 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.
Tue 4/73:35 pm
SAN
- DEN
1 stop6h 48m
Delta
Sat 4/116:30 am
DEN
- SAN
1 stop4h 25m
Delta
Deal found 3/12![Delta logo]()
$217
This Southwest deal was found by Cheapflights users on 3/12. 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 5/146:55 pm
SAN
- DEN
1 stop4h 30m
Southwest
Fri 5/156:25 pm
DEN
- SAN
1 stop4h 35m
Southwest
Deal found 3/12![Southwest logo]()
$137
This Southwest deal was found by Cheapflights users on 3/13. 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 4/275:55 pm
SAN
- DEN
1 stop4h 00m
Southwest
Thu 4/307:40 am
DEN
- SAN
1 stop4h 40m
Southwest
Deal found 3/13![Southwest logo]()
$137
This Delta deal was found by Cheapflights users on 3/11. 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 7/95:00 pm
SAN
- DEN
1 stop4h 31m
Delta
Wed 7/157:15 pm
DEN
- SAN
1 stop4h 40m
Delta
Deal found 3/11![Delta logo]()
$257
This United Airlines deal was found by Cheapflights users on 3/15. 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.
Thu 5/76:20 am
SAN
- DEN
1 stop7h 06m
United Airlines
Sun 5/107:45 am
DEN
- SAN
Nonstop2h 30m
United Airlines
Deal found 3/15![United Airlines logo]()
$267
This Southwest deal was found by Cheapflights users on 3/12. 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 4/47:20 pm
SAN
- DEN
1 stop4h 20m
Southwest
Tue 4/72:05 pm
DEN
- SAN
2 stops5h 20m
Southwest
Deal found 3/12![Southwest logo]()
$242
This Delta deal was found by Cheapflights users on 3/14. 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.
Tue 8/185:00 pm
SAN
- DEN
1 stop4h 31m
Delta
Sun 8/236:30 am
DEN
- SAN
1 stop4h 57m
Delta
Deal found 3/14![Delta logo]()
$277
This United Airlines deal was found by Cheapflights users on 3/13. 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.
Tue 5/51:35 pm
SAN
- DEN
1 stop6h 13m
United Airlines
Wed 5/65:20 am
DEN
- SAN
1 stop5h 38m
United Airlines
Deal found 3/13![United Airlines logo]()
$307
This United Airlines deal was found by Cheapflights users on 3/11. 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.
Sun 6/286:27 pm
SAN
- DEN
1 stop5h 20m
United Airlines
Sun 7/55:32 am
DEN
- SAN
1 stop5h 36m
United Airlines
Deal found 3/11![United Airlines logo]()
$462
Last-minute flights from San Diego to BoulderDiscover last-minute flight deals from San Diego to Boulder. Data last updated March 17, 2026 and is based on user searches.
Discover last-minute flight deals from San Diego to Boulder. Data last updated March 17, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/69:28 pm
SAN
- DEN
Nonstop2h 33m
Frontier
Thu 4/96:15 am
DEN
- SAN
Nonstop2h 37m
Frontier
Deal found 3/13![Frontier logo]()
$93
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 4/712:00 pm
SAN
- DEN
Nonstop2h 34m
Frontier
Thu 4/96:15 am
DEN
- SAN
Nonstop2h 37m
Frontier
Deal found 3/13![Frontier logo]()
$81
This Frontier deal was found by Cheapflights users on 3/13. 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.
Mon 4/139:28 pm
SAN
- DEN
Nonstop2h 33m
Frontier
Wed 4/156:18 pm
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/13![Frontier logo]()
$72
This Expedia deal was found by Cheapflights users on 3/15. 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/171:48 pm
SAN
- DEN
Nonstop2h 36m
Multiple Airlines
Sun 4/197:00 am
DEN
- SAN
Nonstop2h 34m
Multiple Airlines
Deal found 3/15![Multiple Airlines logo]()
$87
This Cheapflightsfares deal was found by Cheapflights users on 3/13. 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 4/1712:25 pm
SAN
- DEN
Nonstop2h 34m
Frontier
Sun 4/197:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/13![Frontier logo]()
$94
This Flightnetwork deal was found by Cheapflights users on 3/14. 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.
Wed 4/2210:30 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sun 4/267:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/14![Frontier logo]()
$69
This Super.com deal was found by Cheapflights users on 3/16. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sun 4/267:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/16![Frontier logo]()
$67
This Cheapflightsfares deal was found by Cheapflights users on 3/15. 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 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Sat 4/256:30 pm
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/15![Frontier logo]()
$68
This Frontier deal was found by Cheapflights users on 3/16. 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.
Thu 4/236:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Mon 4/2710:29 pm
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/16![Frontier logo]()
$82
This Super.com deal was found by Cheapflights users on 3/13. 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 4/306:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Mon 5/47:00 am
DEN
- SAN
Nonstop2h 34m
Frontier
Deal found 3/13![Frontier logo]()
$91
This Gotogate deal was found by Cheapflights users on 3/16. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/306:25 am
SAN
- DEN
Nonstop2h 37m
Frontier
Thu 5/77:12 am
DEN
- SAN
Nonstop2h 30m
Frontier
Deal found 3/16![Frontier logo]()
$92
One-way flights from San Diego to BoulderSearch for one-way flight options from San Diego to Boulder. Find affordable one-way fares based on user searches. Data last updated March 17, 2026.
Search for one-way flight options from San Diego to Boulder. Find affordable one-way fares based on user searches. Data last updated March 17, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 3/13. 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.
Sat 5/236:25 am
SAN
- DEN
Nonstop2h 36m
Frontier
Deal found 3/13![Frontier logo]()
$54
This Kiwi.com deal was found by Cheapflights users on 3/11. 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 4/78:05 pm
SAN
- DEN
Nonstop2h 39m
Hawaiian Airlines
Deal found 3/11![Hawaiian Airlines logo]()
$55
This Southwest deal was found by Cheapflights users on 3/11. 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 4/296:20 am
SAN
- DEN
1 stop4h 20m
Southwest
Deal found 3/11![Southwest logo]()
$56
This Kiwi.com deal was found by Cheapflights users on 3/13. 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 6/146:25 am
SAN
- DEN
Nonstop2h 44m
Frontier
Deal found 3/13![Frontier logo]()
$58
This United Airlines deal was found by Cheapflights users on 3/12. 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.
Thu 4/27:14 pm
SAN
- DEN
Nonstop2h 31m
United Airlines
Deal found 3/12![United Airlines logo]()
$59
This Southwest deal was found by Cheapflights users on 3/11. 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 5/138:40 am
SAN
- DEN
2 stops5h 25m
Southwest
Deal found 3/11![Southwest logo]()
$61
This WAYA deal was found by Cheapflights users on 3/15. 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.
Tue 4/1412:29 pm
SAN
- DEN
1 stop8h 15m
Frontier
Deal found 3/15![Frontier logo]()
$63
This Southwest deal was found by Cheapflights users on 3/13. 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 4/136:50 pm
SAN
- DEN
1 stop3h 55m
Southwest
Deal found 3/13![Southwest logo]()
$64
This Kiwi.com deal was found by Cheapflights users on 3/16. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/124:17 pm
SAN
- DEN
1 stop4h 34m
Frontier
Deal found 3/16![Frontier logo]()
$65
This Cheapflightsfares deal was found by Cheapflights users on 3/15. 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.
Sat 4/49:28 pm
SAN
- DEN
Nonstop2h 33m
Frontier
Deal found 3/15![Frontier logo]()
$66
This Trip.com deal was found by Cheapflights users on 3/11. 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 6/29:37 am
SAN
- DEN
Nonstop2h 30m
Frontier
Deal found 3/11![Frontier logo]()
$67
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 March 17, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $63 (Kiwi.com) |
One-way from | $54 (Cheapflightsfares) |
Popular in | June |
Cheapest in | February |
Average price | $198 |
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 March 17, 2026.
Use the filters below to find and compare flights from San Diego to Boulder that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Wed 4/1
7:45 pm-12:45 am
1 stop4h 00m
Denver Intl
Sat 4/4
5:25 am-7:05 am
Nonstop2h 40m
$123
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 5/14
6:55 pm-12:25 am
1 stop4h 30m
Denver Intl
Fri 5/15
6:25 pm-10:00 pm
1 stop4h 35m
$137
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Mon 4/27
5:55 pm-10:55 pm
1 stop4h 00m
Denver Intl
Thu 4/30
7:40 am-11:20 am
1 stop4h 40m
$137
Quickest round-trip
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Fri 4/3
6:32 am-10:09 am
Nonstop2h 37m
Denver Intl
Sun 4/5
7:45 am-9:16 am
Nonstop2h 31m
$146
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Tue 4/7
3:35 pm-11:23 pm
1 stop6h 48m
Denver Intl
Sat 4/11
6:30 am-9:55 am
1 stop4h 25m
$217
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Sat 4/4
7:20 pm-12:40 am
1 stop4h 20m
Denver Intl
Tue 4/7
2:05 pm-6:25 pm
2 stops5h 20m
$242
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 7/9
5:00 pm-10:31 pm
1 stop4h 31m
Denver Intl
Wed 7/15
7:15 pm-10:55 pm
1 stop4h 40m
$257
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Thu 5/7
6:20 am-2:26 pm
1 stop7h 06m
Denver Intl
Sun 5/10
7:45 am-9:15 am
Nonstop2h 30m
$267
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Tue 8/18
5:00 pm-10:31 pm
1 stop4h 31m
Denver Intl
Sun 8/23
6:30 am-10:27 am
1 stop4h 57m
$277
San DiegoDenver
SAN - DEN
SANDEN
San Diego
Tue 5/5
1:35 pm-8:48 pm
1 stop6h 13m
Denver Intl
Wed 5/6
5:20 am-9:58 am
1 stop5h 38m
$307
Showing 1-10 of 21 resultsSorted by cheapest first
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.
SAN-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 Diego to Boulder
SAN-BD9
SAN-DEN
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 March 13, 2026.
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, 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 March 17, 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 March 14, 2026.
Travelers seeking maximum savings on their San Diego to Boulder flight should consider departing on Friday evenings when fares are most often at their lowest. Tuesday 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 March 17, 2026.
The most flights from SAN to BD9 are scheduled on a Friday (36 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (14 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 March 17, 2026.
See what other customers who have flown with Southwest,Alaska Airlines, andHawaiian 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.
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Entertainment
7.5
Overall
8.0
Crew
8.6
Boarding
8.1
Food
7.0
Comfort
8.0
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 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
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Complete your trip
Complete your trip to Boulder by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from San Diego to Boulder by cabin class
Find flights from San Diego to Boulder, based on your preferred cabin class, be it economy, premium economy, business, or first class.
San Diego and Boulder flights
Browse other San Diego and Boulder flight options. Last updated on March 17, 2026.
Other flights from San Diego
Browse through other flights departing from San Diego. Flights are based on user searches made on Cheapflights and were last updated on March 17, 2026.
Popular flight searches
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San Diego to Boulder flights
Consider these flights traveling from San Diego to Boulder.
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 March 17, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$53 | Average$155 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$68 | Average$177 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$107 | Average$194 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$117 | Average$294 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$119 | Average$327 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$218 | Average$344 | FlexibilityNo cancel fee | On-time71% |