$75+ Cheap flights from Seattle (SEA) to Boulder, CO
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 11/18. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — DEN
Oct 17 — Oct 241
Round-trip
1 adult, Economy
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Find cheap flights from Seattle 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 Seattle/Tacoma Intl to Boulder are usually found in January or February, booked 74 days in advance, depart on a Friday or Thursday and return on a Friday
Cheap flight deals from Seattle to Boulder
Cheapest
Best
Last-minute
One-way
Cheapest flights from Seattle to BoulderExplore the most affordable flight options available from Seattle to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2026.
Explore the most affordable flight options available from Seattle to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 17, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/314:27 pm -
Nonstop2h 48m
Tue 11/310:55 pm -
1 stop20h 59m
Deal found 9/12![Frontier logo]()
$130
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 10/314:27 pm -
Nonstop2h 48m
Mon 11/21:04 pm -
Nonstop3h 08m
Deal found 9/13![Frontier logo]()
$139
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/204:27 pm -
Nonstop2h 50m
Thu 10/221:07 pm -
Nonstop3h 05m
Deal found 9/14![Frontier logo]()
$142
This Priceline deal was found by Cheapflights users on 9/12. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/34:27 pm -
Nonstop2h 54m
Tue 10/61:07 pm -
Nonstop3h 01m
Deal found 9/12![Frontier logo]()
$144
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/194:27 pm -
Nonstop2h 50m
Thu 10/227:31 am -
1 stop27h 17m
Deal found 9/12![Frontier logo]()
$145
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/224:27 pm -
Nonstop2h 50m
Sun 10/251:07 pm -
Nonstop3h 05m
Deal found 9/12![Frontier logo]()
$146
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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.
Wed 11/114:27 pm -
Nonstop2h 48m
Fri 11/131:04 pm -
Nonstop3h 08m
Deal found 9/13![Frontier logo]()
$147
This deal was found by Cheapflights users on 9/12. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/224:27 pm -
Nonstop2h 54m
Thu 9/241:07 pm -
Nonstop3h 01m
Deal found 9/12![Frontier logo]()
$149
This deal was found by Cheapflights users on 9/16. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/284:27 pm -
Nonstop2h 54m
Sun 10/41:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$150
This Frontier deal was found by Cheapflights users on 9/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/64:27 pm -
Nonstop2h 54m
Wed 10/79:05 am -
1 stop12h 35m
Deal found 9/15![Frontier logo]()
$151
This Super.com deal was found by Cheapflights users on 9/16. 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.
Mon 10/54:27 pm -
Nonstop2h 54m
Wed 10/71:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$152
This deal was found by Cheapflights users on 9/16. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/2910:57 am -
1 stop6h 36m
Fri 10/21:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$153
Best flights from Seattle to BoulderDiscover carefully curated flight deals from Seattle to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated September 17, 2026.
Discover carefully curated flight deals from Seattle to Boulder that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated September 17, 2026.
This Delta deal was found by Cheapflights users on 9/15. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/39:05 am -
Nonstop2h 44m
Tue 11/101:14 pm -
Nonstop3h 11m
Deal found 9/15![Delta logo]()
$195
This Southwest deal was found by Cheapflights users on 9/15. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/288:55 am -
2 stops9h 30m
Tue 11/38:45 am -
2 stops8h 15m
Deal found 9/15![Southwest logo]()
$225
This Alaska Airlines deal was found by Cheapflights users on 9/13. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/710:09 am -
Nonstop2h 44m
Thu 12/107:24 pm -
Nonstop3h 16m
Deal found 9/13![Alaska Airlines logo]()
$317
This Delta deal was found by Cheapflights users on 9/15. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/268:00 pm -
Nonstop2h 55m
Thu 11/51:55 pm -
Nonstop3h 13m
Deal found 9/15![Delta logo]()
$259
This Southwest deal was found by Cheapflights users on 9/14. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/49:25 am -
Nonstop2h 35m
Sat 12/51:40 pm -
2 stops7h 30m
Deal found 9/14![Southwest logo]()
$260
This Southwest deal was found by Cheapflights users on 9/14. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/65:35 am -
1 stop5h 40m
Sat 10/104:20 pm -
1 stop7h 05m
Deal found 9/14![Southwest logo]()
$272
This Southwest deal was found by Cheapflights users on 9/16. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/111:35 am -
2 stops8h 30m
Wed 12/912:35 pm -
2 stops7h 05m
Deal found 9/16![Southwest logo]()
$277
This Southwest deal was found by Cheapflights users on 9/15. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/104:15 pm -
1 stop5h 35m
Mon 10/1912:45 pm -
2 stops8h 20m
Deal found 9/15![Southwest logo]()
$281
This Southwest deal was found by Cheapflights users on 9/16. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/185:40 am -
2 stops8h 35m
Sat 11/215:25 pm -
2 stops7h 25m
Deal found 9/16![Southwest logo]()
$281
This Southwest deal was found by Cheapflights users on 9/16. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/137:55 am -
1 stop7h 50m
Tue 12/1512:35 pm -
2 stops7h 05m
Deal found 9/16![Southwest logo]()
$298
This Southwest deal was found by Cheapflights users on 9/12. 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.
Wed 11/2512:15 am -
1 stop9h 45m
Tue 12/12:25 pm -
2 stops10h 10m
Deal found 9/12![Southwest logo]()
$322
Last-minute flights from Seattle to BoulderDiscover last-minute flight deals from Seattle to Boulder. Data last updated September 17, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Boulder. Data last updated September 17, 2026 and is based on user searches.
This deal was found by Cheapflights users on 9/12. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/224:27 pm -
Nonstop2h 54m
Thu 9/241:07 pm -
Nonstop3h 01m
Deal found 9/12![Frontier logo]()
$149
This deal was found by Cheapflights users on 9/16. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 9/284:27 pm -
Nonstop2h 54m
Sun 10/41:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$150
This deal was found by Cheapflights users on 9/16. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/2910:57 am -
1 stop6h 36m
Fri 10/21:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$153
This Priceline deal was found by Cheapflights users on 9/12. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/34:27 pm -
Nonstop2h 54m
Tue 10/61:07 pm -
Nonstop3h 01m
Deal found 9/12![Frontier logo]()
$144
This Super.com deal was found by Cheapflights users on 9/16. 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.
Mon 10/54:27 pm -
Nonstop2h 54m
Wed 10/71:07 pm -
Nonstop3h 01m
Deal found 9/16![Frontier logo]()
$152
This Frontier deal was found by Cheapflights users on 9/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/54:27 pm -
Nonstop2h 54m
Tue 10/61:07 pm -
Nonstop3h 01m
Deal found 9/15![Frontier logo]()
$154
This Frontier deal was found by Cheapflights users on 9/15. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/64:27 pm -
Nonstop2h 54m
Wed 10/79:05 am -
1 stop12h 35m
Deal found 9/15![Frontier logo]()
$151
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/194:27 pm -
Nonstop2h 50m
Thu 10/227:31 am -
1 stop27h 17m
Deal found 9/12![Frontier logo]()
$145
This Cheapflightsfares deal was found by Cheapflights users on 9/14. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/204:27 pm -
Nonstop2h 50m
Thu 10/221:07 pm -
Nonstop3h 05m
Deal found 9/14![Frontier logo]()
$142
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/224:27 pm -
Nonstop2h 50m
Sun 10/251:07 pm -
Nonstop3h 05m
Deal found 9/12![Frontier logo]()
$146
This Cheapflightsfares deal was found by Cheapflights users on 9/12. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/314:27 pm -
Nonstop2h 48m
Tue 11/310:55 pm -
1 stop20h 59m
Deal found 9/12![Frontier logo]()
$130
This Cheapflightsfares deal was found by Cheapflights users on 9/13. 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 10/314:27 pm -
Nonstop2h 48m
Mon 11/21:04 pm -
Nonstop3h 08m
Deal found 9/13![Frontier logo]()
$139
One-way flights from Seattle to BoulderSearch for one-way flight options from Seattle to Boulder. Find affordable one-way fares based on user searches. Data last updated September 17, 2026.
Search for one-way flight options from Seattle to Boulder. Find affordable one-way fares based on user searches. Data last updated September 17, 2026.
This Kiwi.com deal was found by Cheapflights users on 9/12. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/188:09 pm -
1 stop12h 36m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/12![Frontier logo]()
$75
This Super.com deal was found by Cheapflights users on 9/12. 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.
Sat 10/104:27 pm -
Nonstop2h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/12![Frontier logo]()
$80
This Super.com deal was found by Cheapflights users on 9/17. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/610:57 am -
1 stop6h 36m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/17![Frontier logo]()
$86
This Cheapflightsfares deal was found by Cheapflights users on 9/15. 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.
Tue 10/278:09 pm -
1 stop18h 02m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/15![Frontier logo]()
$87
This Booking.com deal was found by Cheapflights users on 9/15. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/208:00 pm -
1 stop20h 34m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/15![Frontier logo]()
$88
This Super.com deal was found by Cheapflights users on 9/16. 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.
Wed 10/74:27 pm -
Nonstop2h 54m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$89
This FlightHub deal was found by Cheapflights users on 9/12. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/148:00 pm -
1 stop18h 14m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/12![Frontier logo]()
$90
This Cheapflightsfares deal was found by Cheapflights users on 9/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/94:27 pm -
Nonstop2h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/16![Frontier logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 9/15. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 10/198:00 pm -
1 stop12h 30m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 9/15![Frontier logo]()
$95
Find flight deals from Seattle to Boulder
Keep the following information in mind while searching for Seattle to Boulder flight deals. Data was last updated September 17, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $130 (Cheapflightsfares) |
One-way from | $75 (Kiwi.com) |
Popular in | June |
Cheapest in | January |
Average price | $276 |
Cheapflights Fare Finder
Customize your flight search to find flights from Seattle 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 7,457,451 searches. Data last updated September 17, 2026.
Use the filters below to find and compare flights from Seattle to Boulder that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
Quickest round-trip
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Tue 12/15
1:35 pm-5:05 pm
Nonstop2h 30m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$99
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Wed 10/14
2:30 pm-11:53 pm
1 stop8h 23m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$108
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Sat 10/24
11:05 am-5:50 pm
1 stop5h 45m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$108
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Sat 11/7
9:55 am-6:45 pm
1 stop7h 50m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$108
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Wed 11/4
11:35 am-9:05 pm
2 stops8h 30m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$113
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Sat 11/14
6:00 am-4:02 pm
1 stop9h 02m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$122
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Thu 11/19
9:25 am-1:00 pm
Nonstop2h 35m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$131
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Wed 10/7
8:00 pm-11:55 pm
Nonstop2h 55m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$136
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Thu 10/29
7:40 am-5:45 pm
2 stops9h 05m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$145
SeattleDenver
SEA Seattle/Tacoma Intl - DEN Denver Intl
SEADEN
Seattle/Tacoma Intl
Thu 11/12
7:30 am-5:55 pm
2 stops9h 25m
Denver Intl
Wed 12/31
12:00 am-11:00 pm
Nonstop0h 00m
$145
Showing 1-10 of 22 resultsSorted by cheapest first
Best time to book a flight from Seattle to Boulder
Have a flexible travel schedule? Discover the best time to fly to Boulder from Seattle with our price prediction graph.
SEA-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 Seattle to Boulder
SEA-BD9
SEA-DEN
What is the cheapest time of day to fly from SEA to BD9?
Find hourly flight availability from Seattle 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 September 17, 2026.
Unlike in the morning, when flights are generally more expensive, you can save up to 31% on flights from Seattle to Boulder by exploring options for tickets in the evening.
Weekly flight availability from Seattle to Boulder
Explore weekly flight availability from Seattle 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 September 17, 2026.
The most flights from SEA to BD9 are scheduled on a Tuesday (39 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (22 on average).
How much does it cost to fly round-trip from Seattle to Boulder?
Airfare is below average for this route at the moment.
Seattle to Boulder flights typically cost between $182 and $347 in October.The cheapest round-trip price found within the last 5 days was $130 on Frontier (Oct 31-Nov 3).
What is the cheapest day to fly from Seattle to Boulder?
Use this chart to determine the cheapest time to fly round-trip from Seattle to Boulder. Price data was last updated on September 12, 2026.
Travelers seeking maximum savings on their Seattle to Boulder flight should consider departing on Thursday evenings when fares are most often at their lowest. Sunday mornings 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 September 17, 2026.
See what other customers who have flown with Southwest,Alaska Airlines, andDelta from Seattle 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.
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Crew
8.6
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Related info for your journey
Find useful and relevant information for your journey from Seattle 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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Seattle and Boulder flights
Browse other Seattle and Boulder flight options. Last updated on September 17, 2026.
Other flights from Seattle
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Top 6 airlines flying from Seattle to Boulder
Discover the top 6 airlines that operate flights from Seattle 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 7,457,451 searches. Data last updated September 17, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$55 | Average$195 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$96 | Average$291 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$114 | Average$360 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$117 | Average$313 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$138 | Average$357 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$200 | Average$328 | FlexibilityNo cancel fee | On-time62% |