Carrier performance at one airport

UA→DEN

United Airlines at Denver International

Departures: 106,792
Period: June 2025 to May 2026
Routes: 25
Rank here: #3 of 9

United Airlines at Denver lands a B+, about a point 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 106,792 flights, of which Delta Air Lines flew 11,605 at 82.4% on time.

Measured against the airport rather than the country, United Airlines runs 2 points ahead of the 76.0% weighted average across all carriers at DEN. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.

On time

78.2%

105,985 completed departures

Avg delay

65 min

Across delayed flights only

Cancelled

0.48%

At DEN, this carrier only

Rank here

Of 9 carriers clearing the floor at DEN

These figures cover 107,000 flights between June 2025 and May 2026. The median arrival is 5 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.

Against the competition

Every carrier at DEN, ranked

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.4% of the time; Allegiant Air manages 65.1%. Sample sizes sit next to every figure, because a two-point gap across 413 flights means less than a ten-point one.

On-time performance of all carriers departing DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	11,605	82.4%	79 min	1.36%	B
SkyWest Airlines	75,448	79.4%	79 min	1.19%	B
United Airlines (this page)	106,792	78.2%	65 min	0.48%	B+
Frontier Airlines	22,257	77.1%	68 min	0.76%	B+
American Airlines	8,855	76.6%	104 min	2.03%	B
Alaska Airlines	2,642	74.3%	58 min	0.87%	C+
Southwest Airlines	89,073	69.6%	55 min	0.71%	C+
JetBlue Airways	1,242	69.0%	91 min	2.66%	C
Allegiant Air	413	65.1%	128 min	1.45%	C

The spread between Delta and Allegiant is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.

Route by route

Where United Airlines flies from DEN

United Airlines operates 25 routes out of DEN with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.

United Airlines routes from DEN
Route	Flights	On time	Avg delay	Cancelled	Grade
DEN to IAH · Houston	3,854	77.7%	65 min	0.34%	B+
DEN to ORD · Chicago	3,701	71.3%	75 min	0.73%	C+
DEN to SFO · San Francisco	3,367	73.0%	65 min	0.45%	C+
DEN to EWR · Newark	3,293	76.4%	81 min	1.55%	B
DEN to LAX · Los Angeles	3,059	84.8%	59 min	0.00%	B+
DEN to IAD · Washington	2,785	83.6%	67 min	0.61%	B+
DEN to LAS · Las Vegas	2,458	78.5%	65 min	0.37%	B+
DEN to PHX · Phoenix	2,378	79.9%	65 min	0.38%	B+
DEN to SAN · San Diego	2,090	80.0%	60 min	0.48%	B+
DEN to LGA · New York	2,013	73.9%	69 min	1.89%	C
DEN to AUS · Austin	1,932	79.6%	64 min	0.62%	B+
DEN to DFW · Dallas-Fort Worth	1,920	76.5%	68 min	0.83%	B+
DEN to BOS · Boston	1,916	76.4%	69 min	0.84%	B+
DEN to SEA · Seattle	1,904	79.4%	56 min	0.63%	B+
DEN to SNA · Santa Ana	1,870	84.7%	51 min	0.32%	B+
DEN to PDX · Portland	1,822	82.1%	59 min	0.44%	B+
DEN to SMF · Sacramento	1,802	80.7%	64 min	0.33%	B+
DEN to MCO · Orlando	1,780	81.8%	74 min	0.39%	B+
DEN to MSP · Minneapolis	1,434	79.9%	70 min	0.42%	B+
DEN to RNO · Reno	1,384	76.5%	67 min	0.14%	B+
DEN to SLC · Salt Lake City	1,353	77.3%	60 min	0.22%	B+
DEN to MCI · Kansas City	1,296	76.5%	67 min	0.31%	B+
DEN to OMA · Omaha	1,287	76.2%	63 min	0.39%	B+
DEN to FLL · Fort Lauderdale	1,250	81.5%	59 min	0.32%	B+
DEN to SAT · San Antonio	1,206	81.0%	62 min	0.25%	B+

Departure window

Best time of day for this operation

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am5,346 flights91.3%
8am–11am21,753 flights85.5%
11am–2pm25,897 flights82.0%
2pm–5pm12,920 flights75.6%
5pm–8pm32,980 flights70.4%
8pm–5am7,896 flights73.2%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 91.3% of the time, against 70.4% for the evening 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

Seasonal pattern

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

July is the worst month at 62.4% on time, 25 points below April, the best at 87.0%. 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.

Delay causes

What holds this operation up

Late-arriving aircraft
47%
Carrier
27%
National Airspace System
24%
Extreme weather
2%
Security
0%

47% 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 1.50 million reported delay minutes here, that single category outweighs weather by 19 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.

Cancellations are rare at 0.48%, 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.

7.5% 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.

106,792 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 87.0% on time and July 62.4%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else.

Common questions

United Airlines at DEN

How often is United Airlines at 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 21.8% of the 106,792 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on United Airlines at DEN?

Delta Air Lines leads at 82.4% on time across 11,605 flights. Allegiant Air is at the other end on 65.1%, a gap of 17 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 United Airlines at DEN?

The 5am–8am departure window is the strongest at 91.3% on time. The 5pm–8pm window is the weakest at 70.4%, 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 United Airlines at DEN?

July is the weakest month at 62.4% on time, compared with 87.0% in April. Across the year that is 25 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

Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.

Key figures