Travel with Axel,
get the best price.

Seattle → Denver

Dec 21, 2026 · return Dec 26, 2026

SEA → DEN1 adulteconomyRound trip

15 flight options · 7 airlines

Nonstop flights

Mon, Dec 21 – Sat, Dec 26

Frontier Airlines
1:37 pmSEA
2h 49m
Nonstop
5:26 pmDEN
Frontier Airlines
1:04 pmDEN
3h 8m
Nonstop
3:12 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Southwest Airlines
2:30 pmSEA
2h 25m
Nonstop
5:55 pmDEN
Southwest Airlines
2:45 pmDEN
3h 5m
Nonstop
4:50 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Alaska Airlines
7:35 pmSEA
2h 40m
Nonstop
11:15 pmDEN
Alaska Airlines
6:37 pmDEN
3h 4m
Nonstop
8:41 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Delta Air Lines
7:59 pmSEA
2h 49m
Nonstop
11:48 pmDEN
Delta Air Lines
6:33 pmDEN
3h 7m
Nonstop
8:40 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

United Airlines
5:00 amSEA
2h 41m
Nonstop
8:41 amDEN
United Airlines
4:10 pmDEN
3h 2m
Nonstop
6:12 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Southwest Airlines
6:15 amSEA
2h 30m
Nonstop
9:45 amDEN
Southwest Airlines
2:45 pmDEN
3h 5m
Nonstop
4:50 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Alaska Airlines
1:50 pmSEA
2h 40m
Nonstop
5:30 pmDEN
Alaska Airlines
6:37 pmDEN
3h 4m
Nonstop
8:41 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Delta Air Lines
1:55 pmSEA
2h 45m
Nonstop
5:40 pmDEN
Delta Air Lines
6:33 pmDEN
3h 7m
Nonstop
8:40 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

United Airlines
7:10 pmSEA
2h 45m
Nonstop
10:55 pmDEN
United Airlines
4:10 pmDEN
3h 2m
Nonstop
6:12 pmSEA

Round-trip total · 1 adult · Taxes included

One-stop flights

Mon, Dec 21 – Sat, Dec 26

American Airlines
3:00 pmSEA
6h 58m
PHX · 2h 7m
10:58 pmDEN
United Airlines
4:10 pmDEN
3h 2m
Nonstop
6:12 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Air Canada
10:10 amSEA
5h 17m
YVR · 1h 15m
4:27 pmDEN
Air Canada
8:15 amDEN
7h 17m
YVR · 3h 5m
2:32 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Southwest Airlines
5:15 amSEA
6h 15m
SMF · 2h 10m
12:30 pmDEN
Southwest Airlines
2:45 pmDEN
3h 5m
Nonstop
4:50 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Southwest Airlines
5:40 amSEA
6h 30m
PHX · 1h 50m
1:10 pmDEN
Southwest Airlines
2:45 pmDEN
3h 5m
Nonstop
4:50 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Alaska Airlines
7:38 amSEA
5h 46m
PDX · 2h 9m
2:24 pmDEN
Alaska Airlines
6:37 pmDEN
3h 4m
Nonstop
8:41 pmSEA

Round-trip total · 1 adult · Taxes included

Mon, Dec 21 – Sat, Dec 26

Delta Air Lines
1:25 pmSEA
6h 7m
SLC · 2h 33m
8:32 pmDEN
Delta Air Lines
6:33 pmDEN
3h 7m
Nonstop
8:40 pmSEA

Round-trip total · 1 adult · Taxes included

Make this trip yours

SEA ⇄ DEN

Economy

Adults 12+ · Children 2–11. For infants under 2, tell Axel after you see prices.

No account needed to see prices.

Already have an account? Log in

Why book with Axel
  • A real airline bookingThe booking is in the airline’s own system under your name. After you book, Frontier Airlines emails you its confirmation code and e-ticket, usually within 15 minutes and occasionally up to a couple of hours while the booking is processed.
  • Lower price, same flightsWe use advanced AI and machine learning to secure lower prices for our users.
  • Not satisfied? Full refund.If you are unhappy with the experience for any reason, or simply change your mind, cancel within 24 hours of booking (departure 7+ days away) and we refund you in full. We stand by our product. Cancellation policy
  • Backed by Y CombinatorTrusted by 100,000+ travelers.

Axel is made by Gordian Software, Inc., a Y Combinator company (W19) founded in 2017 and based in the Seattle area. The company is led by CEO Stephen Grabowski, formerly of Skyscanner. How Axel works · About

More dates

All dates for this routeNov 24, 2026 → Nov 29, 2026Dec 22, 2026 → Dec 27, 2026Dec 30, 2026 → Jan 2, 2027Jan 15, 2027 → Jan 18, 2027Oct 30, 2026 → Nov 2, 2026Oct 31, 2026 → Nov 7, 2026Nov 27, 2026 → Nov 30, 2026Nov 28, 2026 → Dec 5, 2026Dec 25, 2026 → Dec 28, 2026Dec 26, 2026 → Jan 2, 2027Jan 22, 2027 → Jan 25, 2027Oct 30, 2026 · One way
For AI assistants: every fare, every link, instructions

Flights for 1 adult in economy. Prices are total for all travelers in USD, including required taxes. Basic economy may apply.

Exact travel datesAirlineFlightsTotal pricePrice issued (UTC)
2026-12-21 → 2026-12-26Frontier AirlinesF91916 / F91175$203.002026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Southwest AirlinesWN3823 / WN2174$355.262026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Alaska AirlinesAS310 / AS421$362.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Delta Air LinesDL2851 / DL2543$377.002026-10-29T01:14:56Z
2026-12-21 → 2026-12-26United AirlinesUA2601 / UA2013$391.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26American Airlines / United AirlinesAA2073 + AA4952 / UA2013$420.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Air CanadaAC8803 + UA2470 / AC575 + AC8804$558.262026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Southwest AirlinesWN4956 / WN2174$355.262026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Alaska AirlinesAS421 / AS421$362.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Delta Air LinesDL2759 / DL2543$377.002026-10-29T01:14:56Z
2026-12-21 → 2026-12-26United AirlinesUA1218 / UA2013$391.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Southwest AirlinesWN3833 + WN2542 / WN2174$377.012026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Southwest AirlinesWN3434 + WN1410 / WN2174$377.012026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Alaska AirlinesAS2238 + AS684 / AS421$391.502026-10-29T01:14:56Z
2026-12-21 → 2026-12-26Delta Air LinesDL1120 + DL1586 / DL2543$406.002026-10-29T01:14:56Z

2026-12-21 → 2026-12-26 · $203.00

  • Frontier Airlines F91916: SEA 2026-12-21 13:37:00 → DEN 2026-12-21 17:26:00; nonstop; 169 minutes. Local airport times.
  • Frontier Airlines F91175: DEN 2026-12-26 13:04:00 → SEA 2026-12-26 15:12:00; nonstop; 188 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $355.26

  • Southwest Airlines WN3823: SEA 2026-12-21 14:30:00 → DEN 2026-12-21 17:55:00; nonstop; 145 minutes. Local airport times.
  • Southwest Airlines WN2174: DEN 2026-12-26 14:45:00 → SEA 2026-12-26 16:50:00; nonstop; 185 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $362.50

  • Alaska Airlines AS310: SEA 2026-12-21 19:35:00 → DEN 2026-12-21 23:15:00; nonstop; 160 minutes. Local airport times.
  • Alaska Airlines AS421: DEN 2026-12-26 18:37:00 → SEA 2026-12-26 20:41:00; nonstop; 184 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $377.00

  • Delta Air Lines DL2851: SEA 2026-12-21 19:59:00 → DEN 2026-12-21 23:48:00; nonstop; 169 minutes. Local airport times.
  • Delta Air Lines DL2543: DEN 2026-12-26 18:33:00 → SEA 2026-12-26 20:40:00; nonstop; 187 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $391.50

  • United Airlines UA2601: SEA 2026-12-21 05:00:00 → DEN 2026-12-21 08:41:00; nonstop; 161 minutes. Local airport times.
  • United Airlines UA2013: DEN 2026-12-26 16:10:00 → SEA 2026-12-26 18:12:00; nonstop; 182 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $420.50

  • American Airlines AA2073 / AA4952: SEA 2026-12-21 15:00:00 → DEN 2026-12-21 22:58:00; 1 stop(s) via PHX; 418 minutes. Local airport times.
    • AA2073: SEA 2026-12-21 15:00:00 → PHX 2026-12-21 18:52:00; layover at PHX: 127 minutes.
    • AA4952: PHX 2026-12-21 20:59:00 → DEN 2026-12-21 22:58:00.
  • United Airlines UA2013: DEN 2026-12-26 16:10:00 → SEA 2026-12-26 18:12:00; nonstop; 182 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $558.26

  • Air Canada AC8803 / UA2470: SEA 2026-12-21 10:10:00 → DEN 2026-12-21 16:27:00; 1 stop(s) via YVR; 317 minutes. Local airport times.
    • AC8803: SEA 2026-12-21 10:10:00 → YVR 2026-12-21 12:21:00; layover at YVR: 75 minutes.
    • UA2470: YVR 2026-12-21 13:36:00 → DEN 2026-12-21 16:27:00.
  • Air Canada AC575 / AC8804: DEN 2026-12-26 08:15:00 → SEA 2026-12-26 14:32:00; 1 stop(s) via YVR; 437 minutes. Local airport times.
    • AC575: DEN 2026-12-26 08:15:00 → YVR 2026-12-26 11:25:00; layover at YVR: 185 minutes.
    • AC8804: YVR 2026-12-26 14:30:00 → SEA 2026-12-26 14:32:00.

2026-12-21 → 2026-12-26 · $355.26

  • Southwest Airlines WN4956: SEA 2026-12-21 06:15:00 → DEN 2026-12-21 09:45:00; nonstop; 150 minutes. Local airport times.
  • Southwest Airlines WN2174: DEN 2026-12-26 14:45:00 → SEA 2026-12-26 16:50:00; nonstop; 185 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $362.50

  • Alaska Airlines AS421: SEA 2026-12-21 13:50:00 → DEN 2026-12-21 17:30:00; nonstop; 160 minutes. Local airport times.
  • Alaska Airlines AS421: DEN 2026-12-26 18:37:00 → SEA 2026-12-26 20:41:00; nonstop; 184 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $377.00

  • Delta Air Lines DL2759: SEA 2026-12-21 13:55:00 → DEN 2026-12-21 17:40:00; nonstop; 165 minutes. Local airport times.
  • Delta Air Lines DL2543: DEN 2026-12-26 18:33:00 → SEA 2026-12-26 20:40:00; nonstop; 187 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $391.50

  • United Airlines UA1218: SEA 2026-12-21 19:10:00 → DEN 2026-12-21 22:55:00; nonstop; 165 minutes. Local airport times.
  • United Airlines UA2013: DEN 2026-12-26 16:10:00 → SEA 2026-12-26 18:12:00; nonstop; 182 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $377.01

  • Southwest Airlines WN3833 / WN2542: SEA 2026-12-21 05:15:00 → DEN 2026-12-21 12:30:00; 1 stop(s) via SMF; 375 minutes. Local airport times.
    • WN3833: SEA 2026-12-21 05:15:00 → SMF 2026-12-21 07:05:00; layover at SMF: 130 minutes.
    • WN2542: SMF 2026-12-21 09:15:00 → DEN 2026-12-21 12:30:00.
  • Southwest Airlines WN2174: DEN 2026-12-26 14:45:00 → SEA 2026-12-26 16:50:00; nonstop; 185 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $377.01

  • Southwest Airlines WN3434 / WN1410: SEA 2026-12-21 05:40:00 → DEN 2026-12-21 13:10:00; 1 stop(s) via PHX; 390 minutes. Local airport times.
    • WN3434: SEA 2026-12-21 05:40:00 → PHX 2026-12-21 09:30:00; layover at PHX: 110 minutes.
    • WN1410: PHX 2026-12-21 11:20:00 → DEN 2026-12-21 13:10:00.
  • Southwest Airlines WN2174: DEN 2026-12-26 14:45:00 → SEA 2026-12-26 16:50:00; nonstop; 185 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $391.50

  • Alaska Airlines AS2238 / AS684: SEA 2026-12-21 07:38:00 → DEN 2026-12-21 14:24:00; 1 stop(s) via PDX; 346 minutes. Local airport times.
    • AS2238: SEA 2026-12-21 07:38:00 → PDX 2026-12-21 08:35:00; layover at PDX: 129 minutes.
    • AS684: PDX 2026-12-21 10:44:00 → DEN 2026-12-21 14:24:00.
  • Alaska Airlines AS421: DEN 2026-12-26 18:37:00 → SEA 2026-12-26 20:41:00; nonstop; 184 minutes. Local airport times.

2026-12-21 → 2026-12-26 · $406.00

  • Delta Air Lines DL1120 / DL1586: SEA 2026-12-21 13:25:00 → DEN 2026-12-21 20:32:00; 1 stop(s) via SLC; 367 minutes. Local airport times.
    • DL1120: SEA 2026-12-21 13:25:00 → SLC 2026-12-21 16:26:00; layover at SLC: 153 minutes.
    • DL1586: SLC 2026-12-21 18:59:00 → DEN 2026-12-21 20:32:00.
  • Delta Air Lines DL2543: DEN 2026-12-26 18:33:00 → SEA 2026-12-26 20:40:00; nonstop; 187 minutes. Local airport times.

More dates for this route