Route reliability record
DEN→LAS
Denver to Las Vegas
- Flights
- 7,108
- Period
- July 2025 to June 2026
- Distance
- 628 mi
- Carriers
- 3
This route sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 7,108 flights, of which United Airlines flew 2,420 at 78.6% on time.
United Airlines is the most reliable of the three carriers covered here at 78.6% on time across 2,420 flights.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 7,050 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.66%
National rate is 1.81%
Best carrier
United
78.6% on time across 2,420 flights
These figures cover 7,108 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% 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 DEN to LAS
The choice of carrier is not cosmetic here. United Airlines arrives on time 78.6% of the time; Southwest Airlines manages 72.3%. Sample sizes sit next to every figure, because a two-point gap across 3,131 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,420 | 78.6% | 66 min | 0.37% | B+ |
| Frontier Airlines | 1,557 | 76.3% | 71 min | 0.96% | B+ |
| Southwest Airlines | 3,131 | 72.3% | 57 min | 0.73% | C+ |
United leads Southwest by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 31 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am937 flights93.5%
- 8am–11am1,214 flights86.3%
- 11am–2pm1,408 flights77.6%
- 2pm–5pm1,136 flights68.8%
- 5pm–8pm1,302 flights63.0%
- 8pm–5am1,111 flights66.2%
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 63.0% on time, against 93.5% 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 1,408 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.
July is the worst month at 62.6% on time, 22 points below February, the best at 84.2%. 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. March was the busiest month here, with 666 flights.
Across the week, Tuesday is the strongest day at 81.1% on time and Thursday the weakest at 69.3%. 12 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 48% of the 109,000 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.
- 48%Late-arriving aircraft
- 26%Carrier
- 23%National Airspace System
- 3%Extreme weather
- 0%Security
48% 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 109,000 reported delay minutes here, that single category outweighs weather by 18 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 108,940 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 93.5% on time here.
Cancellations are rare at 0.66%, 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
8.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.
The 628 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 77.0% on time across 7,088 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 7,108 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. February runs 84.2% on time and July 62.6%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 7,050 completed flights over 12 months sit behind that.
Common questions
DEN to LAS questions
How often is DEN 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 24.7% of the 7,108 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to LAS?
United Airlines leads at 78.6% on time across 2,420 flights. Southwest Airlines is at the other end on 72.3%, a gap of 6 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 LAS?
The 5am–8am departure window is the strongest at 93.5% on time. The 5pm–8pm window is the weakest at 63.0%, 31 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 July delays on DEN to LAS?
July is the weakest month at 62.6% on time, compared with 84.2% in February. 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 DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Harry Reid International (LAS) delay statistics
- United Airlines on-time record78.6%
- Frontier Airlines on-time record76.3%
- Southwest Airlines on-time record72.3%
- 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. DEN to LAS and LAS to DEN 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.