Carrier route record
UADEN→SFO
United Airlines · Denver to San Francisco
- Flights
- 3,373
- Period
- July 2025 to June 2026
- Share of route
- 62%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on DEN to SFO sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 3,373 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 604 at 67.2% on time.
The national on-time rate over the same period is 77.6%, so United on DEN to SFO runs 6 points behind the country as a whole. Across a thousand flights that is about 64 extra late arrivals.
Key figures
On time
71.2%
Arrivals under 15 minutes late, of 3,358 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.42%
National rate is 1.81%
Whole route
65.8%
Every carrier on DEN to SFO, 5,415 flights
These figures cover 3,373 flights between July 2025 and June 2026. Beyond the headline rate, 9.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
United against every carrier on DEN to SFO
United flew 3,373 of the 5,415 flights on DEN to SFO, most of the route. Its 71.2% on time is 5 points better than the route as a whole, which runs 65.8%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from United at 71.2% to Southwest at 52.6%.
The choice of carrier is not cosmetic here. Frontier Airlines arrives on time 67.2% of the time; Southwest Airlines manages 52.6%. Sample sizes sit next to every figure, because a two-point gap across 1,438 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 3,373 | 71.2% | 63 min | 0.42% | C+ |
| Frontier Airlines | 604 | 67.2% | 55 min | 0.83% | C+ |
| Southwest Airlines | 1,438 | 52.6% | 59 min | 0.49% | F+ |
The spread between Frontier and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
United flight numbers on DEN to SFO
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 27 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am647 flights86.2%
- 8am–11am482 flights69.0%
- 11am–2pm715 flights76.1%
- 2pm–5pm383 flights73.8%
- 5pm–8pm748 flights59.4%
- 8pm–5am398 flights60.4%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 59.4% on time, against 86.2% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 748 flights scheduled in it.
Across the year
United on DEN to SFO through the year
June is the worst month at 51.0% on time, 35 points below March, the best at 86.3%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. May was the busiest month here, with 310 flights.
Across the week, Tuesday is the strongest day at 79.3% on time and Thursday the weakest at 64.6%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. National Airspace System accounts for 45% of the 61,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 45%National Airspace System
- 36%Late-arriving aircraft
- 19%Carrier
- 0%Extreme weather
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 61,000 reported delay minutes here, that single category outweighs weather by 36 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 61,145 reported delay minutes.
45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 28,000 minutes out of 61,000, against a national NAS share of 21%.
Cancellations are rare at 0.42%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.8% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 967 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 82.2% on time across 3,370 flights, 11 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 11 points of difference.
The sample behind these figures is 3,373 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking United on DEN to SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 86.3% on time and June 51.0%, a swing of 35 points. If the dates move at all, move them out of June before you think about anything else. 3,358 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to SFO, every carrier
- United on SFO to DEN, the return leg
- Frontier Airlines on DEN to SFO67.2%
- Southwest Airlines on DEN to SFO52.6%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- San Francisco International (SFO) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.