Route reliability record

LAS→SFO

Las Vegas to San Francisco

Flights: 6,060
Period: July 2025 to June 2026
Distance: 414 mi
Carriers: 5

This route draws a D+. Roughly one flight in three arrive 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 6,060 flights, of which United Airlines flew 2,756 at 67.5% on time.

United Airlines is the most reliable of the four carriers covered here at 67.5% on time across 2,756 flights.

On time

62.8%

Arrivals under 15 minutes late, of 6,017 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

0.68%

National rate is 1.81%

Best carrier

United

67.5% on time across 2,756 flights

These figures cover 6,060 flights between July 2025 and June 2026. Beyond the headline rate, 11.8% 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

Which airline is most reliable on LAS to SFO

The choice of carrier is not cosmetic here. United Airlines arrives on time 67.5% of the time; Southwest Airlines manages 48.8%. Sample sizes sit next to every figure, because a two-point gap across 1,310 flights means less than a ten-point one.

On-time performance by carrier on LAS to SFO
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	3	100.0%	—	0.00%	A+
United Airlines	2,756	67.5%	61 min	0.44%	C+
Alaska Airlines	1,116	66.5%	52 min	1.08%	C
Frontier Airlines	875	64.3%	70 min	1.37%	D
Southwest Airlines	1,310	48.8%	54 min	0.38%	F+

The spread between United and Southwest is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 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 35 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am1,109 flights80.5%
8am–11am847 flights56.9%
11am–2pm1,176 flights68.7%
2pm–5pm1,028 flights66.0%
5pm–8pm1,065 flights52.6%
8pm–5am835 flights45.9%

Scale runs 35% to 85%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 45.9% on time, against 80.5% 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 11am–2pm window is the busiest, with 1,176 flights scheduled in it.

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.

Darker means more delays. Figures are on-time percentages.March best, June worst

June is the worst month at 40.0% on time, 43 points below March, the best at 83.3%. 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 534 flights.

Across the week, Saturday is the strongest day at 73.4% on time and Thursday the weakest at 58.3%. 15 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. National Airspace System accounts for 52% of the 131,000 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.

National Airspace System
52%
Late-arriving aircraft
31%
Carrier
16%
Extreme weather
1%
Security
0%

52% 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 68,000 minutes out of 131,000, against a national NAS share of 21%. The split is drawn from 131,193 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 80.5% on time here.

Cancellations are rare at 0.68%, 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. 11.8% 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.

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 74.1% on time across 6,066 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 6,060 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. March runs 83.3% on time and June 40.0%, a swing of 43 points. If the dates move at all, move them out of June before you think about anything else. 6,017 completed flights over 12 months sit behind that.

Common questions

LAS to SFO questions

How often is LAS to SFO delayed?

Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 37.2% of the 6,060 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on LAS to SFO?

United Airlines leads at 67.5% on time across 2,756 flights. Southwest Airlines is at the other end on 48.8%, a gap of 19 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 LAS to SFO?

The 5am–8am departure window is the strongest at 80.5% on time. The 8pm–5am window is the weakest at 45.9%, 35 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 LAS to SFO?

June is the weakest month at 40.0% on time, compared with 83.3% 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.

Where to go next

Direction matters. LAS to SFO and SFO to LAS 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.

Key figures