$94+ Cheap flights from Seattle (SEA) 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 9/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA ā DEN
Sep 1 ā Sep 81
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 āFind dealsā2. 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 providerās pricing and select the best option for you! Book through your favorite providerās website for a seamless experience.Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Boulder are usually found in January or October, booked 74 days in advance, depart on a Friday or Saturday 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 August 2, 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 August 2, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/217:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Mon 8/247:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 8/2![Frontier logo]()
$136
This Frontier deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 8/187:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Wed 8/197:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 7/30![Frontier logo]()
$138
This Kiwi.com deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Mon 10/54:27 pm
SEA
- DEN
Nonstop2h 54m
Frontier
Fri 10/167:45 am
DEN
- SEA
Nonstop3h 06m
Frontier
Deal found 8/1![Frontier logo]()
$139
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 9/228:15 pm
SEA
- DEN
1 stop12h 17m
Frontier
Tue 9/291:07 pm
DEN
- SEA
Nonstop3h 01m
Frontier
Deal found 7/30![Frontier logo]()
$140
This Cheapflightsfares deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 9/194:27 pm
SEA
- DEN
Nonstop2h 54m
Frontier
Tue 9/221:07 pm
DEN
- SEA
Nonstop3h 01m
Frontier
Deal found 7/31![Frontier logo]()
$141
This Cheapflightsfares deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/217:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Wed 8/2611:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 7/31![Frontier logo]()
$142
This Frontier deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 10/177:41 pm
SEA
- DEN
Nonstop2h 53m
Frontier
Tue 10/207:45 am
DEN
- SEA
Nonstop3h 06m
Frontier
Deal found 7/29![Frontier logo]()
$143
This Frontier deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sun 8/237:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Tue 8/2511:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 7/31![Frontier logo]()
$144
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 11/107:41 pm
SEA
- DEN
Nonstop2h 53m
Frontier
Sun 11/157:45 am
DEN
- SEA
Nonstop3h 06m
Frontier
Deal found 7/30![Frontier logo]()
$145
This Cheapflightsfares deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Thu 10/14:27 pm
SEA
- DEN
Nonstop2h 54m
Frontier
Mon 10/51:07 pm
DEN
- SEA
Nonstop3h 01m
Frontier
Deal found 7/30![Frontier logo]()
$146
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 8/262:37 pm
SEA
- DEN
Nonstop2h 56m
Frontier
Sat 8/298:45 am
DEN
- SEA
1 stop11h 53m
Frontier
Deal found 7/29![Frontier logo]()
$147
This Frontier deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Thu 10/87:41 pm
SEA
- DEN
Nonstop2h 53m
Frontier
Tue 10/137:45 am
DEN
- SEA
Nonstop3h 06m
Frontier
Deal found 7/29![Frontier logo]()
$148
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 August 2, 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 August 2, 2026.
This Alaska Airlines deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Alaska Airlines is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 9/111:41 am
SEA
- DEN
1 stop6h 45m
Alaska Airlines
Tue 9/81:43 pm
DEN
- SEA
1 stop20h 37m
Alaska Airlines
Deal found 8/2![Alaska Airlines logo]()
$243
This Southwest deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/283:25 pm
SEA
- DEN
2 stops7h 20m
Southwest
Wed 9/94:15 pm
DEN
- SEA
Nonstop2h 55m
Southwest
Deal found 7/30![Southwest logo]()
$247
This Delta deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Delta is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 8/159:40 am
SEA
- DEN
1 stop4h 22m
Delta
Sat 8/226:28 pm
DEN
- SEA
1 stop4h 37m
Delta
Deal found 7/31![Delta logo]()
$277
This Alaska Airlines deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Alaska Airlines is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 9/211:41 am
SEA
- DEN
1 stop8h 32m
Alaska Airlines
Wed 9/166:17 am
DEN
- SEA
1 stop7h 22m
Alaska Airlines
Deal found 8/2![Alaska Airlines logo]()
$243
This Southwest deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 8/186:10 pm
SEA
- DEN
Nonstop2h 45m
Southwest
Wed 8/2612:50 pm
DEN
- SEA
2 stops8h 25m
Southwest
Deal found 8/1![Southwest logo]()
$262
This Alaska Airlines deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Alaska Airlines is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 9/98:41 am
SEA
- DEN
1 stop11h 32m
Alaska Airlines
Wed 9/166:17 am
DEN
- SEA
1 stop13h 35m
Alaska Airlines
Deal found 8/1![Alaska Airlines logo]()
$243
This Southwest deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 9/191:35 pm
SEA
- DEN
1 stop5h 40m
Southwest
Tue 9/222:40 pm
DEN
- SEA
2 stops7h 35m
Southwest
Deal found 7/29![Southwest logo]()
$272
This Alaska Airlines deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Alaska Airlines is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 1/2011:30 am
SEA
- DEN
Nonstop2h 46m
Alaska Airlines
Wed 2/35:00 pm
DEN
- SEA
Nonstop3h 03m
Alaska Airlines
Deal found 8/1![Alaska Airlines logo]()
$267
This Southwest deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/215:00 am
SEA
- DEN
2 stops8h 20m
Southwest
Tue 8/252:40 pm
DEN
- SEA
2 stops7h 35m
Southwest
Deal found 8/1![Southwest logo]()
$282
This Southwest deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 10/179:45 am
SEA
- DEN
1 stop5h 35m
Southwest
Mon 10/1912:45 pm
DEN
- SEA
2 stops8h 20m
Southwest
Deal found 7/29![Southwest logo]()
$298
This Southwest deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Southwest is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Mon 8/245:00 am
SEA
- DEN
2 stops8h 20m
Southwest
Sat 8/291:35 pm
DEN
- SEA
2 stops7h 55m
Southwest
Deal found 8/2![Southwest logo]()
$302
Last-minute flights from Seattle to BoulderDiscover last-minute flight deals from Seattle to Boulder. Data last updated August 2, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Boulder. Data last updated August 2, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 8/187:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Wed 8/197:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 7/30![Frontier logo]()
$138
This Cheapflightsfares deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 8/192:37 pm
SEA
- DEN
Nonstop2h 56m
Frontier
Sat 8/2211:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 7/30![Frontier logo]()
$145
This Cheapflightsfares deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/217:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Mon 8/247:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 8/2![Frontier logo]()
$136
This Cheapflightsfares deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/217:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Wed 8/2611:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 7/31![Frontier logo]()
$142
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/219:29 pm
SEA
- DEN
1 stop10h 36m
Frontier
Sun 8/237:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 7/29![Frontier logo]()
$148
This Kiwi.com deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 8/222:37 pm
SEA
- DEN
Nonstop2h 56m
Frontier
Wed 8/2611:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 8/2![Frontier logo]()
$140
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 8/2211:54 am
SEA
- DEN
1 stop10h 27m
Frontier
Sun 8/307:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 7/30![Frontier logo]()
$149
This Frontier deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sun 8/237:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Tue 8/2511:05 am
DEN
- SEA
Nonstop3h 17m
Frontier
Deal found 7/31![Frontier logo]()
$144
This Kiwi.com deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 8/257:06 pm
SEA
- DEN
Nonstop2h 52m
Frontier
Tue 9/17:25 am
DEN
- SEA
1 stop11h 26m
Frontier
Deal found 8/2![Frontier logo]()
$150
This Kiwi.com deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 8/262:37 pm
SEA
- DEN
Nonstop2h 56m
Frontier
Wed 9/28:45 am
DEN
- SEA
1 stop11h 48m
Frontier
Deal found 7/30![Frontier logo]()
$146
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 8/262:37 pm
SEA
- DEN
Nonstop2h 56m
Frontier
Sat 8/298:45 am
DEN
- SEA
1 stop11h 53m
Frontier
Deal found 7/29![Frontier logo]()
$147
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 8/289:29 pm
SEA
- DEN
1 stop10h 36m
Frontier
Sun 8/307:15 am
DEN
- SEA
Nonstop3h 04m
Frontier
Deal found 7/31![Frontier logo]()
$151
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 August 2, 2026.
Search for one-way flight options from Seattle to Boulder. Find affordable one-way fares based on user searches. Data last updated August 2, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Tue 9/110:34 am
SEA
- DEN
1 stop22h 29m
Frontier
Deal found 7/31![Frontier logo]()
$94
This Priceline deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Priceline is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 12/115:25 pm
SEA
- DEN
Nonstop2h 51m
Frontier
Deal found 7/30![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 7/31. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 8/2910:34 am
SEA
- DEN
1 stop13h 10m
Frontier
Deal found 7/31![Frontier logo]()
$96
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 9/309:45 pm
SEA
- DEN
2 stops16h 20m
Frontier
Deal found 7/29![Frontier logo]()
$97
This Trip.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Trip.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sun 9/1310:53 am
SEA
- DEN
1 stop27h 14m
Frontier
Deal found 7/29![Frontier logo]()
$98
This Delta deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Delta is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 8/291:55 pm
SEA
- DEN
Nonstop2h 53m
Delta
Deal found 7/29![Delta logo]()
$99
This Cheapflightsfares deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Sat 12/55:25 pm
SEA
- DEN
Nonstop2h 51m
Frontier
Deal found 7/30![Frontier logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 7/29. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Kiwi.com is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Wed 9/99:45 pm
SEA
- DEN
2 stops16h 20m
Frontier
Deal found 7/29![Frontier logo]()
$101
This Cheapflightsfares deal was found by Cheapflights users on 8/1. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Cheapflightsfares is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Fri 9/114:27 pm
SEA
- DEN
Nonstop2h 54m
Frontier
Deal found 8/1![Frontier logo]()
$103
This Frontier deal was found by Cheapflights users on 8/2. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Mon 8/311:35 pm
SEA
- DEN
Nonstop2h 59m
Frontier
Deal found 8/2![Frontier logo]()
$104
This Frontier deal was found by Cheapflights users on 7/30. Clicking the āPick Datesā button in this card will allow you to select your dates and further customize your flight criteria. From there, click āFind dealsā, make sure Frontier is selected, and click āCompare selectedā under the list of providers to see comparable flight deals.
Thu 9/104:27 pm
SEA
- DEN
Nonstop2h 54m
Frontier
Deal found 7/30![Frontier logo]()
$105
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 August 2, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $136 (Cheapflightsfares) |
One-way from | $94 (Kiwi.com) |
Popular in | June |
Cheapest in | January |
Average price | $234 |
Cheapflights Fare Finder
Ā
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 2,558,603 searches. Data last updated August 2, 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
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Tue 9/1
11:41 am-7:26 pm
1 stop6h 45m
Denver Intl
Tue 9/8
1:43 pm-9:20 am
1 stop20h 37m
$243
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Wed 9/2
11:41 am-9:13 pm
1 stop8h 32m
Denver Intl
Wed 9/16
6:17 am-12:39 pm
1 stop7h 22m
$243
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Wed 9/9
8:41 am-9:13 pm
1 stop11h 32m
Denver Intl
Wed 9/16
6:17 am-6:52 pm
1 stop13h 35m
$243
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Fri 8/28
3:25 pm-11:45 pm
2 stops7h 20m
Denver Intl
Wed 9/9
4:15 pm-6:10 pm
Nonstop2h 55m
$247
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Tue 8/18
6:10 pm-9:55 pm
Nonstop2h 45m
Denver Intl
Wed 8/26
12:50 pm-8:15 pm
2 stops8h 25m
$262
Quickest round-trip
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Wed 1/20
11:30 am-3:16 pm
Nonstop2h 46m
Denver Intl
Wed 2/3
5:00 pm-7:03 pm
Nonstop3h 03m
$267
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Sat 9/19
1:35 pm-8:15 pm
1 stop5h 40m
Denver Intl
Tue 9/22
2:40 pm-9:15 pm
2 stops7h 35m
$272
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Sat 8/15
9:40 am-3:02 pm
1 stop4h 22m
Denver Intl
Sat 8/22
6:28 pm-10:05 pm
1 stop4h 37m
$277
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Fri 8/21
5:00 am-2:20 pm
2 stops8h 20m
Denver Intl
Tue 8/25
2:40 pm-9:15 pm
2 stops7h 35m
$282
SeattleDenver
SEA - DEN
SEADEN
Seattle/Tacoma Intl
Sat 10/17
9:45 am-4:20 pm
1 stop5h 35m
Denver Intl
Mon 10/19
12:45 pm-8:05 pm
2 stops8h 20m
$298
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 August 2, 2026.
Unlike in the morning, when flights are generally more expensive, you can save up to 28% 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 August 2, 2026.
The most flights from SEA to BD9 are scheduled on a Friday (49 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (11 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 $167 and $322 in August.The cheapest round-trip price found within the last 5 days was $136 on Frontier (Aug 21-Aug 24).
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 August 1, 2026.
Travelers seeking maximum savings on their Seattle to Boulder flight should consider departing on Saturday 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 August 2, 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.
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
Entertainment
7.5
Reviews
1 / 20
2.0
MediocreThomas,Dec 2025
SEA - DEN
Comfort
8.0
Overall
8.0
Boarding
8.1
Crew
8.6
Food
7.0
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.
Browse thousands of different options on Cheapflights for your next trip
Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.
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Alternative routes for Seattle to Boulder
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Boulder by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Seattle to Boulder by cabin class
Find flights from Seattle to Boulder, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Seattle and Boulder flights
Browse other Seattle and Boulder flight options. Last updated on August 2, 2026.
Other flights from Seattle
Browse through other flights departing from Seattle. Flights are based on user searches made on Cheapflights and were last updated on August 2, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Seattle to Boulder flights
Consider these flights traveling from Seattle to Boulder.
Top 7 airlines flying from Seattle to Boulder
Discover the top 7 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 2,558,603 searches. Data last updated August 2, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$55 | Average$182 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$69 | Average$211 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$94 | Average$284 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$117 | Average$340 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$117 | Average$308 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$134 | Average$347 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$200 | Average$328 | FlexibilityNo cancel fee | On-time62% |