Route reliability record
LAX→DEN
Los Angeles to Denver
- Flights
- 7,729
- Period
- June 2025 to May 2026
- Distance
- 862 mi
- Carriers
- 5
This route lands a B+, 4 points better than the national rate of 77.4%. Roughly one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 7,729 flights, of which United Airlines flew 3,062 at 86.5% on time.
United Airlines is the most reliable of the five carriers covered here at 86.5% on time across 3,062 flights.
Key figures
On time
81.5%
Arrivals under 15 minutes late, of 7,669 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.50%
National rate is 1.80%
Best carrier
United
86.5% on time across 3,062 flights
These figures cover 7,729 flights between June 2025 and May 2026. The median arrival is 8 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.
Carrier by carrier
Which airline is most reliable on LAX to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 86.5% of the time; Southwest Airlines manages 75.5%. Sample sizes sit next to every figure, because a two-point gap across 1,931 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 3,062 | 86.5% | 65 min | 0.10% | A+ |
| Frontier Airlines | 731 | 81.9% | 93 min | 1.09% | B |
| SkyWest Airlines | 1,261 | 80.4% | 66 min | 0.79% | B+ |
| Delta Air Lines | 744 | 78.5% | 75 min | 1.34% | B |
| Southwest Airlines | 1,931 | 75.5% | 53 min | 0.41% | B+ |
United leads Southwest by 11 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 21 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,537 flights92.0%
- 8am–11am1,489 flights86.4%
- 11am–2pm1,217 flights82.1%
- 2pm–5pm2,027 flights71.2%
- 5pm–8pm916 flights80.6%
- 8pm–5am543 flights77.6%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.0% of the time, against 71.2% for the afternoon window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
When delays peak on this route
This route's year swings by 16 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 72.8% on time, 16 points below April, the best at 88.7%. 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.
The day of the week is close to irrelevant here: 3 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
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 92,000 reported delay minutes.
- 33%Late-arriving aircraft
- 32%National Airspace System
- 32%Carrier
- 2%Extreme weather
- 0%Security
32% 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 30,000 minutes out of 92,000, against a national NAS share of 21%.
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 92.0% on time here.
Cancellations are rare at 0.50%, below the national 1.80% 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
6.4% of arrivals land an hour or more late, close to the national 8.2%. 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 862 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 79.3% on time across 7,728 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 7,729 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. April runs 88.7% on time and July 72.8%, a swing of 16 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
LAX to DEN questions
How often is LAX to DEN delayed?
Roughly one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.5% of the 7,729 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on LAX to DEN?
United Airlines leads at 86.5% on time across 3,062 flights. Southwest Airlines is at the other end on 75.5%, a gap of 11 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 LAX to DEN?
The 5am–8am departure window is the strongest at 92.0% on time. The 2pm–5pm window is the weakest at 71.2%, 21 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 LAX to DEN?
July is the weakest month at 72.8% on time, compared with 88.7% in April. Across the year that is 16 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 LAX — the return legseparate record
- Los Angeles International (LAX) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on-time record86.5%
- Frontier Airlines on-time record81.9%
- SkyWest Airlines on-time record80.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. LAX to DEN and DEN to LAX 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, June 2025 to May 2026. Updated monthly. How this data is collected.