Carrier route record
UADEN→MIA
United Airlines · Denver to Miami
- Flights
- 932
- Period
- July 2025 to June 2026
- Share of route
- 37%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on DEN to MIA 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 932 flights, with a median arrival 4 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate United on DEN to MIA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.4%
Arrivals under 15 minutes late, of 927 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.11%
National rate is 1.81%
Whole route
74.0%
Every carrier on DEN to MIA, 2,490 flights
These figures cover 932 flights between July 2025 and June 2026. Beyond the headline rate, 8.1% 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
United against every carrier on DEN to MIA
United flew 932 of the 2,490 flights on DEN to MIA, about 37% of it. Its 75.4% on time is about level with the route as a whole at 74.0%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from American at 76.6% to Southwest at 63.2%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| American Airlines | 886 | 76.6% | 102 min | 1.02% | B |
| United Airlines (this page) | 932 | 75.4% | 64 min | 0.11% | B+ |
| Frontier Airlinesthin sample | 349 | 73.6% | 59 min | 1.15% | C |
| Southwest Airlinesthin sample | 323 | 63.2% | 51 min | 0.62% | D+ |
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 13 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am357 flights75.4%
- 11am–2pm42 flights76.2%
- 2pm–5pm296 flights79.0%
- 5pm–8pm149 flights66.4%
- 8pm–5am88 flights78.2%
Scale runs 60% to 85%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 2pm–5pm slot at 79.0% on time, ahead of 5pm–8pm at 66.4%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8am–11am window is the busiest, with 357 flights scheduled in it.
Across the year
United on DEN to MIA through the year
July is the worst month at 58.5% on time, 38 points below April, the best at 96.0%. 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. March was the busiest month here, with 112 flights.
Across the week, Monday is the strongest day at 81.2% on time and Saturday the weakest at 68.8%. 12 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 15,000 reported delay minutes.
- 38%Late-arriving aircraft
- 34%National Airspace System
- 27%Carrier
- 1%Extreme weather
38% 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 15,000 reported delay minutes here, that single category outweighs weather by 25 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 14,536 reported delay minutes.
34% 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 4,923 minutes out of 15,000, against a national NAS share of 21%.
Cancellations are rare at 0.11%, 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
8.1% 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 last about an hour, which a normal layover absorbs.
At 1,709 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 82.1% on time across 932 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 932 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on DEN to MIA
Put together: treat all of this as provisional. 932 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 75.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 927 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to MIA, every carrier
- United on MIA to DEN, the return leg
- American Airlines on DEN to MIA76.6%
- Frontier Airlines on DEN to MIA73.6%
- Southwest Airlines on DEN to MIA63.2%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- Miami International (MIA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.