Route reliability record
SFO→LAS
San Francisco to Las Vegas
- Flights
- 6,066
- Period
- July 2025 to June 2026
- Distance
- 414 mi
- Carriers
- 5
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 77.6%. The late ones land about an hour behind schedule. That rests on 6,066 flights, of which United Airlines flew 2,757 at 79.6% on time.
United Airlines is the most reliable of the four carriers covered here at 79.6% on time across 2,757 flights.
Key figures
On time
74.1%
Arrivals under 15 minutes late, of 6,023 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.81%
Best carrier
United
79.6% on time across 2,757 flights
These figures cover 6,066 flights between July 2025 and June 2026. Beyond the headline rate, 9.9% 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
Which airline is most reliable on SFO to LAS
The choice of carrier is not cosmetic here. United Airlines arrives on time 79.6% of the time; Frontier Airlines manages 65.6%. Sample sizes sit next to every figure, because a two-point gap across 879 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,757 | 79.6% | 55 min | 0.36% | B+ |
| Alaska Airlines | 1,116 | 76.5% | 66 min | 0.81% | B+ |
| Southwest Airlines | 1,312 | 66.3% | 64 min | 0.53% | C+ |
| Frontier Airlines | 879 | 65.6% | 96 min | 1.25% | C |
| SkyWest Airlinesthin sample | 2 | 50.0% | 81 min | 0.00% | F+ |
The spread between United and Frontier is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.
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 32 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am785 flights95.1%
- 8am–11am1,166 flights82.1%
- 11am–2pm1,003 flights64.0%
- 2pm–5pm933 flights63.0%
- 5pm–8pm1,054 flights74.1%
- 8pm–5am1,125 flights69.4%
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.1% of the time, against 63.0% for the afternoon window. That is 32 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 1,166 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 22 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.
Delays peak in April, when the on-time rate falls to 60.3%. August is the strongest month at 82.1%. Moving a flexible trip across that boundary buys 22 points. May was the busiest month here, with 535 flights.
Across the week, Saturday is the strongest day at 83.4% on time and Thursday the weakest at 67.9%. 16 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 55% of the 104,000 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.
- 55%Late-arriving aircraft
- 25%Carrier
- 19%National Airspace System
- 1%Extreme weather
- 0%Security
55% 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 104,000 reported delay minutes here, that single category outweighs weather by 55 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 104,391 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 95.1% on time here.
Cancellations are rare at 0.61%, 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 actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.9% 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.
At 414 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 62.8% on time across 6,060 flights, 11 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 11 points of difference.
The sample behind these figures is 6,066 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 82.1% on time and April 60.3%, a swing of 22 points. If the dates move at all, move them out of April before you think about anything else. 6,023 completed flights over 12 months sit behind that.
Common questions
SFO to LAS questions
How often is SFO to LAS delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.9% of the 6,066 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SFO to LAS?
United Airlines leads at 79.6% on time across 2,757 flights. Frontier Airlines is at the other end on 65.6%, a gap of 14 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 SFO to LAS?
The 5am–8am departure window is the strongest at 95.1% on time. The 2pm–5pm window is the weakest at 63.0%, 32 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 April delays on SFO to LAS?
April is the weakest month at 60.3% on time, compared with 82.1% in August. Across the year that is 22 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
- LAS to SFO — the return legseparate record
- San Francisco International (SFO) delay statistics
- Harry Reid International (LAS) delay statistics
- United Airlines on-time record79.6%
- Alaska Airlines on-time record76.5%
- Southwest Airlines on-time record66.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. SFO to LAS and LAS to SFO are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.