Route reliability record
DEN→SFO
Denver to San Francisco
- Flights
- 5,488
- Period
- September 2025 to August 2026
- Distance
- 967 mi
- Carriers
- 3
This route draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 5,488 DEN to SFO flights, of which United Airlines flew 3,429 at 69.0% on time.
Best time to fly DEN to SFO: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 83.0% of the time and Tuesday flights 72.2%, against 63.2% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 69.0% on time across 3,429 flights.
Key figures
On time
63.2%
Arrivals under 15 minutes late, of 5,463 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.40%
National rate is 1.89%
Best carrier
United
69.0% on time across 3,429 flights
These figures cover 5,488 flights between September 2025 and August 2026. Beyond the headline rate, 13.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on DEN to SFO
The choice of carrier is not cosmetic here. United Airlines arrives on time 69.0% of the time; Southwest Airlines manages 48.3%. Sample sizes sit next to every figure, because a two-point gap across 1,392 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 3,429 | 69.0% | 63 min | 0.23% | C+ |
| Frontier Airlines | 667 | 64.0% | 60 min | 1.05% | D |
| Southwest Airlines | 1,392 | 48.3% | 61 min | 0.50% | F+ |
The spread between United and Southwest is 21 points, wide enough that it should decide the booking. On a hundred trips that is 21 more arrivals inside the on-time window.
Flight by flight
Flights on DEN to SFO
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Denver to San Francisco
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → SJCDenver to San Jose | United Airlines | 81.6% | 81.6% | 0.00% | 8am–11am, Sat | UA 2745 19:30 |
| 2. DEN → SFODenver to San Francisco | United Airlines | 68.8% | 69.0% | 0.23% | 5am–8am, Tue | UA 2367 05:15 |
| 3. DEN → SJCDenver to San Jose | Southwest Airlines | 67.5% | 68.0% | 0.72% | 8am–11am, Tue | — |
| 4. DEN → OAKDenver to Oakland | Southwest Airlines | 64.9% | 65.4% | 0.81% | 5am–8am, Sat | — |
| 5. DEN → SFODenver to San Francisco | Frontier Airlines | 63.3% | 64.0% | 1.05% | 5am–8am, Sat | F9 3439 22:29 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against 21 points between the best and worst carrier.
- 5am–8am933 flights83.0%
- 8am–11am797 flights54.8%
- 11am–2pm1,038 flights64.8%
- 2pm–5pm566 flights67.2%
- 5pm–8pm1,062 flights53.4%
- 8pm–5am1,092 flights58.3%
Scale runs 45% to 90%.
The 5pm–8pm window is where this operation falls apart: 53.4% on time, against 83.0% 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 8pm–5am window is the busiest, with 1,092 flights scheduled in it.
Explore
Filter DEN to SFO by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On DEN to SFO, the best departure window is 5am–8am at 83.0% on time and the worst is 5pm–8pm at 53.4%, a wide gap of 29.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am83.0%
- 8–11am54.8%
- 11am–2pm64.8%
- 2–5pm67.2%
- 5–8pm53.4%
- 8pm–5am58.3%
best all US flightsScale 45% to 95%.
Across the year
When delays peak on this route
This route's year swings by 43 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 39.4% on time, 43 points below March, the best at 82.2%. 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. July was the busiest month here, with 514 flights.
Across the week, Tuesday is the strongest day at 72.2% on time and Thursday the weakest at 57.9%, a spread of 14 points.
Delay causes
Why this route gets delayed
National Airspace System accounts for 48% of the 124,000 delay minutes carriers reported here, and the remaining four split what is left.
- 48%National Airspace System
- 32%Late-arriving aircraft
- 18%Carrier
- 2%Extreme weather
- 0%Security
48% 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 59,000 minutes out of 124,000, against a national NAS share of 21%. The split is drawn from 123,833 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 83.0% on time here.
Cancellations are rare at 0.40%, below the national 1.89% 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 actually costs
13.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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.
The return leg is a different operation and performs like one: it runs 74.7% on time across 5,486 flights, 12 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 12 points of difference.
The sample behind these figures is 5,488 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.
Work out the risk of missing a connection in SFO after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 82.2% on time and June 39.4%, a swing of 43 points. If the dates move at all, move them out of June before you think about anything else. 5,463 completed flights over 12 months sit behind that.
Common questions
DEN to SFO questions
How often is DEN to SFO delayed?
Roughly one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 36.8% of the 5,488 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to SFO?
United Airlines leads at 69.0% on time across 3,429 flights. Southwest Airlines is at the other end on 48.3%, a gap of 21 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on DEN to SFO?
The 5am–8am departure window is the strongest at 83.0% on time. The 5pm–8pm window is the weakest at 53.4%, 30 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on DEN to SFO?
June is the weakest month at 39.4% on time, compared with 82.2% in March. Across the year that is 43 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SFO to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on DEN to SFO69.0%
- Frontier Airlines on DEN to SFO64.0%
- Southwest Airlines on DEN to SFO48.3%
- DEN to PHX, a related route75.6%
- LAX to SFO, a related route60.1%
- DEN to SLC, a related route78.2%
- United Airlines on-time record69.0%
- Frontier Airlines on-time record64.0%
- Southwest Airlines on-time record48.3%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. DEN to SFO and SFO to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.