Route reliability record
SJC→DEN
San Jose to Denver
- Flights
- 2,546
- Period
- September 2025 to August 2026
- Distance
- 948 mi
- Carriers
- 3
This route lands a B+, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 55 minutes on average. That rests on 2,546 SJC to DEN flights, of which United Airlines flew 992 at 89.3% on time.
Best time to fly SJC to DEN: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 96.0% of the time and Saturday flights 88.2%, against 80.6% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
80.6%
Arrivals under 15 minutes late, of 2,527 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.39%
National rate is 1.89%
Best carrier
United
89.3% on time across 992 flights
These figures cover 2,546 flights between September 2025 and August 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Which airline is most reliable on SJC to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 89.3% of the time; Southwest Airlines manages 74.8%. Sample sizes sit next to every figure, because a two-point gap across 1,520 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 992 | 89.3% | 68 min | 0.30% | A+ |
| Frontier Airlinesthin sample | 34 | 85.3% | 47 min | 0.00% | A+ |
| Southwest Airlines | 1,520 | 74.8% | 52 min | 0.46% | C+ |
The spread between United 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.
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Best ways to make this trip
The most reliable ways to fly San Jose to Denver
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. MRY → DENMonterey to Denver | SkyWest Airlines | 92.8% | 92.9% | 0.16% | 5am–8am, Wed | OO 5587 05:00 |
| 2. SJC → DENSan Jose to Denver | United Airlines | 89.0% | 89.3% | 0.30% | 8am–11am, Sat | — |
| 3. SFO → DENSan Francisco to Denver | United Airlines | 82.0% | 82.1% | 0.18% | 5am–8am, Sat | UA 2348 08:35 |
| 4. SJC → DENSan Jose to Denver | Southwest Airlines | 74.5% | 74.8% | 0.46% | 5am–8am, Tue | — |
| 5. OAK → DENOakland to Denver | Southwest Airlines | 71.1% | 71.4% | 0.37% | 5am–8am, Sat | — |
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 26 points, against 15 points between the best and worst carrier.
- 5am–8am332 flights96.0%
- 8am–11am681 flights92.5%
- 11am–2pm396 flights76.3%
- 2pm–5pm723 flights69.7%
- 5pm–8pm369 flights72.0%
- 8pm–5am45 flights71.1%
Scale runs 60% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 96.0% of the time, against 69.7% for the afternoon window. That is 26 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 723 flights scheduled in it.
Explore
Filter SJC to DEN 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 SJC to DEN, the best departure window is 5am–8am at 96.0% on time and the worst is 2pm–5pm at 69.7%, a wide gap of 26.3 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am96.0%
- 8–11am92.5%
- 11am–2pm76.3%
- 2–5pm69.7%
- 5–8pm72.0%
- 8pm–5am71.1%
best all US flightsScale 60% to 100%.
Across the year
When delays peak on this route
This route's year swings by 29 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 64.1% on time, 29 points below January, the best at 93.1%. 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. September was the busiest month here, with 264 flights.
Across the week, Saturday is the strongest day at 88.2% on time and Thursday the weakest at 75.2%, a spread of 13 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 27,000 reported delay minutes.
- 34%National Airspace System
- 34%Late-arriving aircraft
- 30%Carrier
- 2%Extreme weather
- 1%Security
34% 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 9,180 minutes out of 27,000, against a national NAS share of 21%. The split is drawn from 26,905 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 96.0% on time here.
Cancellations are rare at 0.39%, 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
5.6% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.
The 948 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 73.5% on time across 2,547 flights, 7 points below 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 7 points of difference.
The sample behind these figures is 2,546 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 DEN 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. January runs 93.1% on time and June 64.1%, a swing of 29 points. If the dates move at all, move them out of June before you think about anything else. 2,527 completed flights over 12 months sit behind that.
Common questions
SJC to DEN questions
How often is SJC to DEN delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 19.4% of the 2,546 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 55 minutes on average.
Which airline is most reliable on SJC to DEN?
United Airlines leads at 89.3% on time across 992 flights. Southwest Airlines is at the other end on 74.8%, a gap of 15 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 SJC to DEN?
The 5am–8am departure window is the strongest at 96.0% on time. The 2pm–5pm window is the weakest at 69.7%, 26 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 SJC to DEN?
June is the weakest month at 64.1% on time, compared with 93.1% in January. Across the year that is 29 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
- DEN to SJC — the return legseparate record
- Norman Y. Mineta San Jose International (SJC) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on SJC to DEN89.3%
- Southwest Airlines on SJC to DEN74.8%
- SJC to SAN, a related route68.3%
- PHX to DEN, a related route76.7%
- SJC to LAX, a related route85.0%
- United Airlines on-time record89.3%
- Frontier Airlines on-time record85.3%
- Southwest Airlines on-time record74.8%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. SJC to DEN and DEN to SJC 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.