Frontier's Economy Bundle includes a carry-on and seat choice, ideal for budget travelers.
Opt for Premium Bundle for priority boarding and extra legroom, just $20 more than Economy.
Planning a trip from Seattle to Denver? KAYAK’s data-powered insights will help you find cheap flights. Learn the best time to fly, how early to book your ticket, and other tips to secure great prices.
The most affordable time to fly from Seattle to Denver is typically on a Tuesday or Wednesday, with January being the cheapest month overall.
Booking Advance: Purchase tickets at least 15 days in advance for the best rates.
Cheapest Airline: Frontier Airlines generally offers the lowest fares on this route.
Direct Flights: Direct flights, particularly with Frontier, are usually cheaper than those with layovers.
Route Selection: The route from Seattle/Tacoma Intl to Denver Intl is the most cost-effective option.
This feature is powered by ChatGPT: an OpenAI-developed artificial intelligence model trained with KAYAK proprietary data and third-party data not verified by KAYAK.
Low season | January |
---|---|
High season | December |
Cheapest flight | $64 |
Direct departures
Seattle/Tacoma Intl to Denver Intl
Monday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Tuesday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Wednesday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Thursday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Friday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Saturday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Sunday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Direct returns
Denver Intl to Seattle/Tacoma Intl
Monday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Tuesday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Wednesday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Thursday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Friday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Saturday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Sunday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
It was fine, mostly I was just happy to be on my last leg home. No in flight entertainment but that's forgivable since it was only a 2 hour flight.
It was fine, mostly I was just happy to be on my last leg home. No in flight entertainment but that's forgivable since it was only a 2 hour flight.
Was delayed in Newark 24 hours due to mechanical problems. The staff was very helpful in trying to make the best of a trying situation. In SeaTac, they changed gates and times. Usually have no problems from SeaTac.
Flight was cancelled, then rebooked on a flight that I was unable to get through since they had closed the gate.
Terrible. We were bumped off our flight to another and weren't sent notice until we were on our prior flight. We got home four hours later and the airline couldn't have cared less.
Continuously changing delayed departure time. Too much waiting for a short flight. Driving would have been faster.
5 hours delay, while seated moved passengers around on the plane. We were out on the runway, had to return to the gate. Changed tires.
The flight was great, unfortunately the Airport sucked at accommodating connection flight. My Mother had to sleep at the airport, making me feel helpless. Unable to determine if I should sleep or drive 3 hours each way to pick her up.
Despite the delays with boarding and flying out of Seattle, the flight crew was amazing!! This was my second experience flying with Alaska, and given the chance in the future, I would fly with them again.
Terrible. After boarding we sat on the runway for 1.5 hours "25th in line to take off" ... Alaska Air is on 7th terminal , far away from rest of airport
Better sinage at check-in counter on lines for baggage check in and boarding pass check in, specfically at JFK. It was a mess to figure and wasted a lot of people's time.
I was re-booked onto another flight because my original flight was delayed and I would have missed my connector. I ended up in the “C” group after paying extra to be in the “A “ group on the original flight. At least if you’re going to re-book people, re-book them into the same group.
Flight was delayed due to plane not passing inspection And one of the crew had to time out and we had to wait for another one A 3 hour delay
mandatory demand customer to check their carry on because not enough people check bags.
Connecting flight is on time and boarding was a breeze!
Excellent. Would encourage Southwest to keep current boarding procedures with free style seating. Makes for a fantastic experience
As always, the entire Southwest experience was perfect. Purchasing the tickets on the Southwest web site was effortless, departure and arrival gates were spotless and comfortable, plane was clean and comfortable, crew was excellent and flight was on time. Wheelchair service in Las Vegas at departure was somewhat chaotic and disjointed, but I am not sure if that was Southwest problem, airport problem or combination.
Near 4 hour flight with only 1 service. Had to use call button to request water. Internet and power not working until into flight. Internet would stop working during flight.
Very smooth checking in our luggage with a super pleasant SW agent. I enjoyed a fun entertaining movie.
The Southwest employees (all two of them) were very nice and cheerful despite the fact the line to self-check a bag (simply drop it off) was hundreds of people long. Thank God I arrived early to the airport because I stood in this line for at least an hour. Once on the flight that had been delayed by an hour, we had no Wi-Fi and thus no entertainment. Finally, I hope the investor strong arm tactics against Southwest pay off in a short-term windfall to your C-Suite because the rest of you are screwed. I have been a faithful Southwest customer for 15 years due to everything you just got rid of. I'm flying to Idaho and Washington in October, both places I used to simply book with Southwest without a second thought now with Frontier (Washington) and United (Idaho) because they offer everything the "new" Southwest does but cheaper and at better times, destinations, etc. This really makes me sad...
Flights delayed by 4-6 hours. Boarding was a mess and unclear. Bags were not at arrival airport and had never even been put on the plane. No idea when I’ll get them. Don’t fly into Denver!
They changed planes and the new plane couldn’t carry enough fuel to fly across the country so we had to stop in Kansas City to refuel. Flight was delayed .
Flight was too crowded and seats are too small, especially since passengrs are getting larger. Having a middle seat is ALWAYS tough! Woman on my left was large & kept creeping in to my space. Flight personnel were great! Have more savory rather than sweet snacks please.
Flight was crowded and the woman sitting on my left was large & kept crouching in to my space. You need bigger seats or smaller passengers to fit into the seats you DO have! Snack were OK. Would appreciate if airlines had more savory rather than sweet snacks, thank you!
Delayed flight (1hour) plus a long layover after an overnight flight with no backup plane available.
We were delayed, which I think had to do with air traffic control. Otherwise, everything was great.
The boarding process needs to be refined. Sometimes the gate crew calls out the zones and then flip to showing the.zones boarding on the gate monitor display. So, unless you are huddled around the gate lanes watching the monitor, you could miss your boarding zone. Suggest the zones be announced each time a new zone is allowed to board.
The boarding process needs to be refined. Sometimes the gate crew call out the boarding zone, and then flip to the monitor to show which zones are boarding. So unless everyone is gathered around to see the monitor there is usually confusion as wi which zones are boarding.
On time flight. Seat comfort could be better in the Comfort section.
My issue was with TSA agents for delta airlines. My luggage got flagged. The agent was going thru another persons first. He took 20 min to go thru hers. I asked them to bring mine closer so I could sit down . They said you can go sit it will be fine. I said I am supposed to keep my eyes on my bags at all times. The agent was meticulously unwrapping 2 gifts that the lady had and then tried to re warp it. He was trying to be kind i get it but 20 min for me to stand watching him do that was ridiculous. It was 6 am and there were a ton of travelers. Mine was flagged for some air packed tea that I bought in Turkey. My previous delta flight and 2 others before didn’t flag it. Consistency would be nice. Also on the flight the window shades were down for take off and landing - I thought that was very odd I thought they had to remain open for take off and landing.
The flight was an hour and a half late departing which was inconvenient
The entertainment available didn’t work for anyone on the flight. Long 6 hr flight with no entertainment option and the staff didn’t know until an hour into the flight when we made sure they knew about it. They had no way to fix it.
Late FA meant slow boarding. WiFi did not work. I’m a medium plus sized passenger. The seatbelt was for the first time ever barely fitting. And we delayed on the tarmac 40 min
My husband and I had boarded the flight from Denver to Chicago, and one of the last passengers to get on the plane opened the overhead bin above my husband's seat and threw his bag out of the bin to make space for his own. He said, "Mine is bigger!" The flight attendant supported the new passenger. They didn't care that my husband has two artificial knees and must have the foot room in front of his seat to be able to fit his legs in -- and to be able to stand, much less walk, at the end of the flight. I have never seen this happen before, and it was a disaster.
I understand stuff happens, but plane failures are likely due to lack of maintenance. Additionally, air conditioning wasn't working, no snack/drink service, no WiFi. Fortunately, the crew was communicative and light-hearted. United grabbed another plane and we were able to get to our destination.
Had to cancel first flight because Airporter Bus took over 3 hrs to get to airport which resulted in an extra $378 dollar fare . Is there anyway I can be reimbursed for initial fare since it was not my fault? Sent from my iPhone EJ Ledet
Excellent flight. Boarding was efficient and departure was on time. Smooth flight with on time arrival. Deplaning was also efficient.
Our flight was understandably diverted to a small regional airport in Laramie, Wyoming due to weather conditions, which I fully recognize and appreciate. However, the low rating stems from the experience that followed: passengers remained on board for over an hour without the option to deplane and stretch, despite the aircraft being stationary. Although the pilot opened the cabin door, only he was permitted to exit. Meanwhile, passengers grew increasingly uncomfortable as warm summer air entered the cabin through the open door, and being in the second row meant we were impacted immediately. While the flight attendants made efforts to keep everyone at ease, I believe allowing passengers to deplane briefly, given the extended delay, would have significantly improved the overall experience.
I never flew. Flight was canceled. DIA worst airport in the country. Avoid at all costs.
Very rough getting into denver. my kid threw up it was so rough.
Why wasn't this flight departure scheduled eith another crew so that it could leave on time? When we arrived in Denver we had so little time between flights we had run to the connecting flight. We should received some credit for the inconvenience.
I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!
Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.
The experience was good. No frills but I got there safe and sound and on time.
As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.
Frontier Airlines was AWFUL. I was an hour early for my flight and the lady refused to check me in. I had to purchase a whole new ticket with a different airline.
Late, terrible communication, horrible planning of passenger seating until the literal last minute. One of the worst flying experiences of my life. Y'all suck
First of all, we never got on the connecting flight to Denver. They delayed our flight for two hours. If we would have gotten on that flight, we would have been stuck in Denver for 13 hours. So we re- routed our flight for a straight through flight to Oklahoma two days later. THEN, they delayed that flight for two hours. After that we were able to finally get on our flight and come home. Frontier Airlines - one of the worst airlines I have ever been on.
Terrible communication with weather delay, lost baggage, near impossible to reach customer service
My tickets got canceled on me by your site and I didn't have a flight. Then you kept sending me emails on the status of q flight I didn't have tickets for.
Flight was late. Missed connecting in Denver. My new flight is more than 24 hours later and I have no room, vouchers, or compensation, and might also be bumped from the one tomorrow.
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