Carrier route record

UALAX→DEN

United Airlines · Los Angeles to Denver

Flights: 3,067
Period: July 2025 to June 2026
Share of route: 40%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.

United on LAX to DEN earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 3,067 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 762 at 81.9% on time.

Set against the rest of the country, United's LAX to DEN record is 10 points better than the US average of 77.6%. That gap is worth roughly 95 fewer late arrivals for every thousand flights.

On time

87.1%

Arrivals under 15 minutes late, of 3,049 completed flights

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

0.10%

National rate is 1.81%

Whole route

81.7%

Every carrier on LAX to DEN, 7,721 flights

These figures cover 3,067 flights between July 2025 and June 2026. The median arrival is 10 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

United against every carrier on LAX to DEN

United flew 3,067 of the 7,721 flights on LAX to DEN, about 40% of it. Its 87.1% on time is 5 points better than the route as a whole, which runs 81.7%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from United at 87.1% to Southwest at 74.1%.

The choice of carrier is not cosmetic here. Frontier Airlines arrives on time 81.9% of the time; Southwest Airlines manages 74.1%. Sample sizes sit next to every figure, because a two-point gap across 1,917 flights means less than a ten-point one.

On-time performance by carrier on LAX to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines (this page)	3,067	87.1%	68 min	0.10%	A+
Frontier Airlines	762	81.9%	90 min	0.79%	B+
SkyWest Airlines	1,231	81.2%	61 min	0.81%	B+
Delta Air Lines	744	79.7%	85 min	1.48%	B
Southwest Airlines	1,917	74.1%	52 min	0.47%	C+

Frontier leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

United flight numbers on LAX to DEN

Departure window

When United runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 16 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am700 flights93.6%
8am–11am365 flights90.4%
11am–2pm730 flights88.6%
2pm–5pm726 flights77.2%
5pm–8pm522 flights88.1%
8pm–5am24 flights—

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 93.6% of the time, against 77.2% for the afternoon window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 730 flights scheduled in it.

Across the year

United on LAX to DEN through the year

Darker means more delays. Figures are on-time percentages.April best, July worst

July is the worst month at 75.5% on time, 18 points below April, the best at 93.7%. 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. May was the busiest month here, with 277 flights.

Across the week, Sunday is the strongest day at 90.6% on time and Thursday the weakest at 85.1%. 6 points is a smaller lever than departure hour, but it is free.

Delay causes

Why United runs late on this route

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 27,000 reported delay minutes.

National Airspace System
39%
Late-arriving aircraft
33%
Carrier
25%
Extreme weather
2%
Security
0%

39% 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 11,000 minutes out of 27,000, against a national NAS share of 21%. The split is drawn from 26,727 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 93.6% on time here.

Cancellations are rare at 0.10%, 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 costs

Badly late arrivals are rare here: only 4.8% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

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 84.5% on time across 3,064 flights, within 3 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 3,067 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 United on LAX to DEN

Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 93.7% on time and July 75.5%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 3,049 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures