Carrier route record
UAMIA→DEN
United Airlines · Miami to Denver
- 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 MIA to DEN lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 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 932 flights, with a median arrival 10 minutes early.
Set against the rest of the country, United's MIA to DEN record is 5 points better than the US average of 77.6%. That gap is worth roughly 45 fewer late arrivals for every thousand flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 925 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.11%
National rate is 1.81%
Whole route
77.1%
Every carrier on MIA to DEN, 2,491 flights
These figures cover 932 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 MIA to DEN
United flew 932 of the 2,491 flights on MIA to DEN, about 37% of it. Its 82.1% on time is 5 points better than the route as a whole, which runs 77.1%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from Frontier at 82.8% to Southwest at 59.7%. 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 |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 351 | 82.8% | 112 min | 1.42% | B |
| United Airlines (this page) | 932 | 82.1% | 68 min | 0.11% | B+ |
| American Airlines | 885 | 75.7% | 63 min | 0.79% | B+ |
| Southwest Airlinesthin sample | 323 | 59.7% | 57 min | 0.00% | 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 19 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–8am208 flights90.8%
- 8am–11am189 flights92.1%
- 11am–2pm119 flights83.2%
- 2pm–5pm364 flights73.0%
- 5pm–8pm34 flights72.7%
- 8pm–5am18 flights—
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 92.1% of the time, against 72.7% for the evening window. That is 19 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 364 flights scheduled in it.
Across the year
United on MIA to DEN through the year
July is the worst month at 71.6% on time, 23 points below April, the best at 94.7%. 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. March was the busiest month here, with 113 flights.
Across the week, Friday is the strongest day at 84.8% on time and Sunday the weakest at 77.0%. 8 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 11,000 reported delay minutes.
- 35%Late-arriving aircraft
- 30%National Airspace System
- 28%Carrier
- 6%Extreme weather
- 1%Security
35% 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 11,000 reported delay minutes here, that single category outweighs weather by 6 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 11,238 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 92.1% on time here.
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
5.7% 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 75.4% on time across 932 flights, 7 points below 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 MIA to DEN
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 82.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 925 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to DEN, every carrier
- United on DEN to MIA, the return leg
- Frontier Airlines on MIA to DEN82.8%
- American Airlines on MIA to DEN75.7%
- Southwest Airlines on MIA to DEN59.7%
- United Airlines network-wide record
- Miami International (MIA) delay statistics
- Denver International (DEN) 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.