Route reliability record
DEN→SMF
Denver to Sacramento
- Flights
- 3,853
- Period
- September 2025 to August 2026
- Distance
- 909 mi
- Carriers
- 4
This route sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 3,853 DEN to SMF flights, of which United Airlines flew 1,791 at 80.5% on time.
Best time to fly DEN to SMF: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 94.4% of the time and Tuesday flights 78.7%, against 73.2% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 4 points behind the country as a whole. Across a thousand flights that is about 41 extra late arrivals.
Key figures
On time
73.2%
Arrivals under 15 minutes late, of 3,840 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
0.29%
National rate is 1.89%
Best carrier
United
80.5% on time across 1,791 flights
These figures cover 3,853 flights between September 2025 and August 2026. Beyond the headline rate, 8.4% 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 SMF
The choice of carrier is not cosmetic here. United Airlines arrives on time 80.5% of the time; Southwest Airlines manages 65.3%. Sample sizes sit next to every figure, because a two-point gap across 1,866 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 2 | 100.0% | — | 0.00% | A+ |
| Frontier Airlinesthin sample | 194 | 82.4% | 65 min | 0.00% | B+ |
| United Airlines | 1,791 | 80.5% | 62 min | 0.11% | B+ |
| Southwest Airlines | 1,866 | 65.3% | 53 min | 0.48% | 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.
Flight by flight
Flights on DEN to SMF
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 Sacramento
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → SMFDenver to Sacramento | United Airlines | 80.4% | 80.5% | 0.11% | 8am–11am, Tue | UA 2149 08:00 |
| 2. DEN → SMFDenver to Sacramento | Southwest Airlines | 65.0% | 65.3% | 0.48% | 5am–8am, Wed | — |
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 39 points, against 15 points between the best and worst carrier.
- 5am–8am124 flights94.4%
- 8am–11am973 flights88.4%
- 11am–2pm820 flights78.3%
- 2pm–5pm677 flights71.0%
- 5pm–8pm623 flights59.4%
- 8pm–5am636 flights55.2%
Scale runs 45% to 100%.
The 8pm–5am window is where this operation falls apart: 55.2% on time, against 94.4% 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 8am–11am window is the busiest, with 973 flights scheduled in it.
Explore
Filter DEN to SMF 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 SMF, the best departure window is 5am–8am at 94.4% on time and the worst is 8pm–5am at 55.2%, a wide gap of 39.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.4%
- 8–11am88.4%
- 11am–2pm78.3%
- 2–5pm71.0%
- 5–8pm59.4%
- 8pm–5am55.2%
best all US flightsScale 45% to 100%.
Across the year
When delays peak on this route
This route's year swings by 27 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 59.0% on time, 27 points below November, the best at 86.1%. 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. July was the busiest month here, with 395 flights.
Across the week, Tuesday is the strongest day at 78.7% on time and Thursday the weakest at 69.6%, a spread of 9 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 54% of the 58,000 delay minutes carriers reported here, and the remaining four split what is left.
- 54%Late-arriving aircraft
- 35%Carrier
- 10%National Airspace System
- 1%Extreme weather
- 0%Security
54% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 58,000 reported delay minutes here, that single category outweighs weather by 54 to one. The split is drawn from 57,700 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 20,000 of the 58,000 delay minutes reported here.
Cancellations are rare at 0.29%, 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
8.4% 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 an hour, which a normal layover absorbs.
The 909 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 83.1% on time across 3,844 flights, 10 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 10 points of difference.
The sample behind these figures is 3,853 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 SMF 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. November runs 86.1% on time and June 59.0%, a swing of 27 points. If the dates move at all, move them out of June before you think about anything else. 3,840 completed flights over 12 months sit behind that.
Common questions
DEN to SMF questions
How often is DEN to SMF delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.8% of the 3,853 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 SMF?
United Airlines leads at 80.5% on time across 1,791 flights. Southwest Airlines is at the other end on 65.3%, 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 DEN to SMF?
The 5am–8am departure window is the strongest at 94.4% on time. The 8pm–5am window is the weakest at 55.2%, 39 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 SMF?
June is the weakest month at 59.0% on time, compared with 86.1% in November. Across the year that is 27 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
- SMF to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Sacramento International (SMF) delay statistics
- Frontier Airlines on DEN to SMF82.4%
- United Airlines on DEN to SMF80.5%
- Southwest Airlines on DEN to SMF65.3%
- DEN to PHX, a related route75.6%
- LAX to SMF, a related route84.8%
- DEN to SLC, a related route78.2%
- SkyWest Airlines on-time record100.0%
- Frontier Airlines on-time record82.4%
- United Airlines on-time record80.5%
- 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 SMF and SMF 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.