Frontier's Premium Bundle includes priority boarding and extra legroom seats.
Avoid Basic Fare to prevent extra fees for carry-on bags and seat selection.

Planning a trip from San Francisco 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.
For those planning to fly from San Francisco to Denver, it's worth noting that Tuesdays and the month of September are generally the cheapest times to travel. Here are some tips to help you save money on this route:
Booking Advance: Try to book your flight at least 20 days in advance for the best prices.
Cheapest Airline: Frontier Airlines generally offers the cheapest flights on this route.
Direct Flights: Direct flights are significantly more expensive, so consider flights with layovers to save money.
Route Selection: The route from San Francisco to Denver is typically the cheapest.
Airline Selection: Consider flying with Frontier, as they generally offer the cheapest direct flights.
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 | October |
| Cheapest flight | $68 |
Direct departures
San Francisco to Denver Intl
Monday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Tuesday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Wednesday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Thursday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Friday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Saturday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Sunday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Direct returns
Denver Intl to San Francisco
Monday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Tuesday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Wednesday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Thursday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Friday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Saturday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Sunday
Frontier, Southwest, United Airlines
Frontier, Southwest, +1 more
Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.
Sacrament staff are always polite and helpful. Airport is easy to maneuver and boarding is straightforward.
As always, the entire Southwest experience was wonderful, from online booking to flight to baggage retrieval. Very grateful.
The weather could have been better. There was a 40 minute ATC delay in SFO because of marine fog and a micro cell storm delayed landing and take-off at Nashville. The gate was changed 5 minutes from boarding from gate B3 to gate C23 at Nashville airport.
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.
The cabin was quiet for the redeye flight. The area was clean. The staff was great. The 787 Max was in good condition. Drawbacks were that the seat widths were tight for some passengers. The seat padding was at best average and for a long flight uncomfortable.
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...
Delayed flight. Nicest crew member was a SW pilot flying seated next to me who kindly move to seat the final passenger. Flight extra delayed. My cup of refreshment of ginger ale was so packed with ice it was literally 2 sips.
No trays in our seats, we sat in first row, purchased a business class fare. Had to hold our drinks and snack in our hands. No plugs for our cell phones. Had to pay for it a drink cocktail each. Seats so uncomfortable.
Flight wasn’t even full, but too many carry-ons caused us to run out of bin space. New bag fee has folks who would usually check their bags carrying on. Watching Southwest morph into Spirit/Frontier is so sad to watch
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!
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.
Always seated jammed in rear of aircraft Admirals Club food at DFW terminal D was absolute worst food experience and I pay $600/year to eat this dried out junk
Mostly good. Flight was crowded but Airline personnel were very friendly & accommodating. It would be good to have savory snacks rather than just sweet Biscoff cookies.
We were delayed for a “couple of maintenance issues.” They were resolved rather quickly but a computer glitch caused someone in the airport to have to bring a physical copy of the paperwork so we could leave. I don’t know where they had to drive from to get to our plane but it took forever & we were 1 1/2 hrs late in leaving. The flight itself was fine.
It was a red eye flight, so no meals were provided, but it was fine with snacks. The seats felt cramped and almost too narrow.
Very crowded flight but what can you expect these days?? Crew was accommodating.
Because the plane was 90 degrees F, they would not let us board. I wish they had, because it meant we were delayed. It's Texas, of course it's hot. We would have survived.
The seats in economy were appeared to be quite thin and lack sufficient cushioning to be comfortable. Perhaps it was my seating position but the plane seemed notably load.
The entertainment package was vast and the selections were very current. Keep updating it was great.
The seat was so hard my tailbone was aching The crew was kind of a b**** because I made a joke that I didn't care if they close the door I total c*** when she was trying to f****** act like she was mad at me because I said that The flight was bumpy. Sure you didnt have control over that.
Our bags took a long time to get unloaded once we landed.
I liked how when I got on board how fast we ended up taking off but what I truly disliked was how uncomfortable the seats were. There was truly never a time that I could ever get comfortable during both of my flights. The seats could get away during shorter flights but flights 3 hour plus makes it hard to enjoy.
The crew was great and the flight was very smooth. Can’t really judge food since I did not get any because it costs money. The seat was comfortable for what we bought. Thanks!
Crew was great. No entertainment and food and beverage was for purchase only, even water
It was canceled. The flight wasn’t rescheduled, everyone had to figure out their own new arrangements. They said we would get refunded our original fare and receive an additional $150. We received links for $100 only and they expired before we could activate them.
The plane had originated in Las Vegas at 6:30 in the morning and flew to Moline where we boarded. The flight left around 12:30 PM and there were no boxed snacks available and many of the alcoholic beverages were unavailable. I would find it hard to believe that that many of the passengers coming from Las Vegas at 6:30 in the morning, drank and ate that much of the items. I can only come to the conclusion that someone failed to stock the plane for the round-trip. This is a huge revenue failure for the airline and disappointment for the passengers. The flight crew did not seem happy to be there and did not engage with passengers. Allegiant you can do better.
They did not let my husband on the plane with our service animal at the last minute. Do NOT fly this airline with a service animal!
Tight! Seats are not designed for those of us who wear extra-large clothes.
The non-stop flight from Grand Rapids was excellent. I neither expected or needed a budget flight and Allegiant made the trip easy and for an affordable price, Arriving at the Mesa Airport (AZA) is a delight compared to the international airport. For our return flight, we were able to arrive 75 minutes before the flight, return the rental car, check our bag and make it to the gate in plenty of time. That would never happen at most airports.
Easiest flights I’ve ever taken. Plane was comfortable without overly crowded seating.
Terrible. Still have not received the refund from them. They sent it to some account that I don't even know. Spoke with costumer service and they are unable to help.
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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