Frontier's Economy Bundle offers a carry-on and seat choice, ideal for budget travelers.
Consider Premium Bundle for extra legroom and priority boarding at a small additional cost.

Planning a trip from Denver to Seattle? 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.
Based on flight data for the Denver to Seattle route, it's generally cheaper to fly on Saturdays and in the month of January. Here are some tips to help you save money when booking this route:
Cheapest Route: Stick to the direct route from Denver International to Seattle/Tacoma International for the best prices.
Booking Advance: Try to book your flight at least 21 days in advance to get the best rates.
Cheapest Airline: Consider flying with Frontier, as it generally offers the cheapest fares for this route.
Direct or Layover: It's cheaper to fly direct on this route than with a layover.
Route Selection: The direct route from Denver to Seattle is typically the cheapest option.
AI-powered; AI can make mistakes.
| Low season | January |
|---|---|
| High season | July |
| Cheapest flight | $58 |
Direct departures
Denver Intl to Seattle/Tacoma Intl
Monday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Tuesday
Alaska Airlines, Delta, Southwest, +1 more
Alaska Airlines, Delta, +2 more
1
Wednesday
Alaska Airlines, Delta, Southwest, +1 more
Alaska Airlines, Delta, +2 more
1
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
Seattle/Tacoma Intl to Denver Intl
Monday
Alaska Airlines, Delta, Frontier, +2 more
Alaska Airlines, Delta, +3 more
1
2
Tuesday
Alaska Airlines, Delta, Southwest, +1 more
Alaska Airlines, Delta, +2 more
1
Wednesday
Alaska Airlines, Delta, Southwest, +1 more
Alaska Airlines, Delta, +2 more
1
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
Flights were on time, easy boarding, comfort, flight was smooth.... Best travel experience I have ever had
Flights were on time, easy boarding, comfort, flight was smooth.... Best travel experience I have ever had
Second flight in a row that I've been on where the auto bag counter stopped working and they had to manually count cargo before takeoff. Also second flight where my whole fruit and cheese plate looked pretty stale/old. The grapes were very strange tasting to the point where I didn't eat them. Apple slices were just sad/gross looking so also avoided those.
inflight entertainment website was extremely slow to load on my phone
From Las Vegas to Boise all went well. However, our flight was delayed in Boise and I missed my connecting flight from Seattle to Pasco. Moreover, the last flight to Pasco was full and I was booked on the 11:30 flight Sunday and given a hotel accommodation. However, I was scheduled to deliver the Sunday morning service at my church and needed to arrive no later than 10:00. Therefore, I booked a Delta flight scheduled to arrive in Pasco at 23:09. My piece of luggage checked in Las Vegas arrived in Pasco earlier today. I waited at the airport for over an hour last night to speak with an Alaska agent to no avail. I went back after church this morning in search of my piece of luggage and it could not be located. After waiting for 40 minutes to speak to the agent authorized to take my claim, he announced that he was closing the counter to assist on the flight line but not before providing me with a telephone number that would help me with filing my claim. Before I was able to make the call (due to other factors) I received a call from Alaska agent informing me that my luggage had just arrived and I am now waiting for it to be delivered. I deliberately took the more complicated route home to ensure that I would be home in plenty of time to prepare for myself for the Sunday service and accommodate my relatives’ needs. I believe the airport is undermanned given the number of flights coming in and going out. It was fiasco last night with three flights waiting for luggage and another flight landing within minutes. Today’s problems stemmed from a lack of cross training and a serious amount of cargo/baggage going out and too few people scheduled to cover.
My flight from Spokane to Seattle was delayed about 26 minutes. I arrived at Seattle Airport at 3:21. My flight to Idaho Falls left at 3:35 and you all wouldn't wait for me. I ran for the gate and It would have cost you probably 10 min to wait. Now, I'm stuck at the Seattle airport for 5 hours. I would understand if waiting put you 30 min behind or an hour but I checked into that flight, you knew I was coming, and that my flight was delayed.
Honestly the bathroom cabinet under sink fell out and was completely broken. The floor or walkway was worn out and it smelled wierd. But the seats were terrible for comfort. I truly hope that my trip home in February is better.
My first flight was delayed by over an hour, luckily I had Long layovers on an itinerary from hell, because when you book a Saver ticket, they change your itinerary and make it many stops and long layovers, and there were still delays. On the return flight there was a delay in the first leg, Orlando to Seattle, so I got up really early for nothing, and on the last leg Anchorage to Fairbanks, it was over 2 hours late taking off! I didn't get home until 1 :30am! By the time I got my luggage, the flight landed at 1 am. For the departure day, I was up from 6am to when I arrived the next day at 6am in Orlando. So I was up for 22 hours, 3:15am to almost 2 am the next day. On the return day. The moral of the story is, DON"T EVER BUY SAVER TICKETS! You can't even upgrade your seat when you do that and then at the last minute they want Big bucks to upgrade the day before leaving.
I had the worst seat neighbors thry literally snored so loud and the man next to me man spreaded the whole time i couldnt sleep
Service was great! 👍 Seats were small and absolutely not enough leg and feet room!!!
We sat on the tarmac for so long when we got to SeaTac that half the plane missed their connections.
Probably not the fault of Delta but there was delay after delay after delay and I ended up getting home 4 hours later then I should have at 1:30 in the morning
No in flight service, no explanation - FC got service, C+ did not, unsure about Economy. No turbulence to speak of, so I guess another way to cut cost, or promote health and well being of Delta employees? Also, boarding in MEM combined zones, and with overhead space already full on both flights after Zone 2/ Diamond, presents a huge challenge to find a space for a bag. Delta, other than point A to B, is no longer reasonable to fly - very poor experiences, not even taking into account the chastising at the gate and rude crews, across the board.
It would have been better if the flight wasn't delayed by 2.5 hours
Delta’s staff is unmatched. From the gate agents, to the pilots, to the flight attendants… all top of the industry.
Delta flight Delay for ,more that two hours i.e original flight was 6.30 PM and it starts at 8.45 PM, When we connect Delta team for meal vouchers as it is late arrival in designation,But we did not get it as per delta policy , which is not good for mid night arrival,
Inexperienced boarding crew allowed too many bags on to a full flight and delayed takeoff causing a missed connection and unplanned overnight stay. There was a hotel at the airport but Delta would not pay for it offering only to shuttle me to an area hotel. Never even offerred so much as an apology by anyone working for Delta.
Staff was great! Kind and cordial! Middle seat row 28 seat B has a hump in it. Trays were getting stuck when putting down and up. Good flight
Departure was delayed resulting in me missing my connection. Delta did not autimatically find me another flight.
The seats weren’t reclining even though it wasn’t as exit seat
This flight was no comparison to our prior flight. I'm thinking it all has to do with the age of the aircraft.
Yall need to integrate your system with Alaska more efficiently. They booted me off the first flight because of a discrepancy on your end.
The crew at Hawaiian Airlines was fantastic. Kind and hard working. The pilots were great with giving us all the updates to make sure we were informed.
Very good. Nice plane and we sat in economy plus - bigger seats, more room. They served a meal and snacks, and the meal was an apple stuffed pancake that was very good! The snack for us was a hummus sandwich - also very good. The flight attendants were helpful and nice. They have plenty of movies and shows to watch. My only negative -- they changed our flights around and did not adjust the layovers, so we ended up with a very long and unnecessary layover in Honolulu.
I liked the Starlink WiFi but didn't like how they said they were the only airline to offer a free meal and it turns out to be just a standalone sandwich and then charge for snacks to go with it. Rather have the free snacks like Southwest, but have the option to purchase a decent meal for a 5+ hour flight.
Flight scheduled to take off at 5.55pm but it did not take off until 7pm due to some food delivery delay.
Unfortunately, I was put into the middle seat in the first row of premium seating. Sounds nice right? No! that is the worst seat in the plane. I wish I was in economy rather than be in that seat! There is no seat back pocket, no tray table, no charger. Nothing! so unless you're row mates are willing to let you share their basic amenities any flyer should have, you are stuck. It was the worst experience ever! And the flight attendant forgot to take my drink order. I felt like the forgotten flyer.
Delayed and cancelled flights were hard and very stressful, both ways!
The crew was quite good, they came by often with drinks or to collect trash. But what wasn't nice was the flight was over weigh and several people had to be rebooked. I was questioned whether I should have a seat when I was getting to it. The in-flight entertainment kept buffering and interrupting. And the route took the airplane through high winds which caused us a longer flight
Wasn’t on the flight due to Alaska cancellation…also after all the rerouting, I was going to be on a later flight that left SFO at 7:47pm, which meant an almost 6 hour layover. That same Hawaiian flight was delayed for another 2hours.
I had to cancel the flight because with a 3 hour delay for 'unexpected maintenance' in getting to LAX, I couldn't connect to an overseas flight that I had booked on Scandinavian Air.
Sitting on the runway after we land for almost two hours! Not sure if we should blame United or Just Dumpy Vance.
Flight was late - I was downgraded from first class to coach
Crew seemed a bit cranky. No seatback screens. But boarding was efficient and on time and we arrived early.
See previous note about the passenger in Denver who threw my husband's bag out of the overhead bin in order to maker room for his own. And the flight attendant back up the new passenger.
Terrible. They wouldn't allow me on my flight on the 14th..
it was so bad. I tried to board my flight from vancouver to saskatoon. And to my surprise they did not board me cause the flight was changed and no email was send to me. and on my boarding pass which i got from seattle says different flight. I did not knew anyone from Vancouver, air canada crew was rude, i asked for today flight but they were rude and i had early morning dental appointment in saskatoon. I was so much in pain and my whole day is wasted today. and i suffered alot. They did provide me hotel but they did not provide me any food. I am really really disappointed first time had so bad experience with air canada. I may think twice to book it again. If i can get any reply or any composition that would be great. Thanks
Impressed with the service despite turbulence because of the weather. Both flights arrived before their scheduled times.
Great experience…left a bit behind schedule but made up fir that in the air and landed 10 minutes early 😁
Electric plugs didn't work. Entertainment system wasn't working
The design of the light switch on the arm rest is ridiculous.
I am writing to express my disappointment with my recent Frontier Airlines flight. I was charged $99 at the gate because my bag was said to be too large, yet once onboard there was no available overhead bin space, and I was required to place the bag under the seat in front of me anyway. This made the charge feel unnecessary and unfair. Additionally, before the flight even took off, I was asked to move from the seat I paid for into a middle seat so another passenger and her cat could have my seat to themselves. I was not offered compensation or an explanation for being moved from a paid seat. Between the unexpected bag fee and being forced to give up my seat, this experience fell well below acceptable customer service standards. I would appreciate a review of this situation and appropriate compensation.
It was costly and difficult to check in. $85 to take a small suitcase with me, carry on or checked and $75 on the return trip, Plus $25 if I didn't check my self in check in $25, because I couldn't do it on the kiosk. Small very uncomfortable seats, waited on the runway for near an hour each way. It was my worst flight to date.
It was ok. It was expensive to check 2 bags ($75.00 per bag), and then it took a long time to wait for shuttle to take us from one terminal to the terminal where the plane was taking off at LAX. And all of this for a flight where we had to pay for any food or drink that was not water.
It didn’t happen. I booked it and then was told it wasn’t available and then forced to pay far higher prices for a worse option
A 630departure flight Delayed 6hours! They changed my gate, I moved to the new gate. Had our flight on the screen for 12noon departure. I go get above to eat, check screen again and the flight was gone, no notice no announcement, nothing!! They sent my bag on the flight I wasn’t on, got it back to me 3days later. Thank goodness they did refund my money but I will NEVER fly them again.
Due to weather, my flight was delayed, further delayed, then canceled. I eventually got through to a support person who helped me find a different route out of MSP, but to get to DIA, they didn't want to, but eventually did help with the connection ticket purchase. But even this replacement flight was delayed time and time again, and I would have missed my connecting flights and I didn't want to get stuck in a layover city, so after 12 hours at the airport with two young boys who were very tired, we just cancelled our plans and spent the week at home, instead of Nana's.
Plane and crew on board were fine. Everything else was terrible.
The third party booking with cheapflightsfares was awful. Kayak should NOT partner with them. They sold me a bundle including seat selection and carry-on, but did not book the carry-ons with Frontier, so I’m out of pocket for $414 more while I await resolution.
This company socks. It's fraud. They canceled our flight yesterday, and today we were late because of a really long line at the check in bag. At the rebook station, there was ton of people. The workers were all rude. I am gonna make a report to FTC.
Not clean and was told I would get a great seat and it was not great at all