Route reliability record
MIA→DEN
Miami to Denver
- Flights
- 2,444
- Period
- September 2025 to August 2026
- Distance
- 1,709 mi
- Carriers
- 4
This route lands a B+, level with the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 2,444 MIA to DEN flights, of which United Airlines flew 877 at 83.0% on time.
Best time to fly MIA to DEN: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 89.7% of the time and Wednesday flights 81.2%, against 76.8% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.8%
Arrivals under 15 minutes late, of 2,418 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.49%
National rate is 1.89%
Best carrier
United
83.0% on time across 877 flights
These figures cover 2,444 flights between September 2025 and August 2026. The median arrival is 7 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.
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Carrier by carrier
Which airline is most reliable on MIA to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 83.0% of the time; American Airlines manages 76.1%. Sample sizes sit next to every figure, because a two-point gap across 889 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 355 | 83.2% | 91 min | 0.85% | B+ |
| United Airlines | 877 | 83.0% | 73 min | 0.11% | B+ |
| American Airlines | 889 | 76.1% | 58 min | 0.90% | B+ |
| Southwest Airlinesthin sample | 323 | 54.5% | 61 min | 0.00% | F+ |
United leads American by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on MIA to DEN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Miami to Denver
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. FLL → DENFort Lauderdale to Denver | United Airlines | 87.8% | 87.9% | 0.17% | 8am–11am, Thu | — |
| 2. MIA → DENMiami to Denver | United Airlines | 82.9% | 83.0% | 0.11% | 8am–11am, Wed | — |
| 3. MIA → DENMiami to Denver | American Airlines | 75.4% | 76.1% | 0.90% | 8am–11am, Tue | — |
| 4. FLL → DENFort Lauderdale to Denver | Southwest Airlines | 68.2% | 68.2% | 0.00% | 5am–8am, Thu | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 25 points, against 7 points between the best and worst carrier.
- 5am–8am578 flights89.7%
- 8am–11am475 flights87.7%
- 11am–2pm213 flights76.7%
- 2pm–5pm571 flights64.5%
- 5pm–8pm212 flights68.4%
- 8pm–5am395 flights66.7%
Scale runs 55% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.7% of the time, against 64.5% for the afternoon window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 578 flights scheduled in it.
Explore
Filter MIA to DEN by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On MIA to DEN, the best departure window is 5am–8am at 89.7% on time and the worst is 2pm–5pm at 64.5%, a wide gap of 25.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am89.7%
- 8–11am87.7%
- 11am–2pm76.7%
- 2–5pm64.5%
- 5–8pm68.4%
- 8pm–5am66.7%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 14 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.
June is the worst month at 69.7% on time, 14 points below February, the best at 83.6%. 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 281 flights.
Across the week, Wednesday is the strongest day at 81.2% on time and Sunday the weakest at 73.9%, a spread of 7 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 42% of the 37,000 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Late-arriving aircraft
- 30%Carrier
- 23%National Airspace System
- 4%Extreme weather
- 1%Security
42% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 37,000 reported delay minutes here, that single category outweighs weather by 10 to one. The split is drawn from 37,224 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 89.7% on time here.
Cancellations are rare at 0.49%, below the national 1.89% 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
7.4% of arrivals land an hour or more late, close to the national 8.3%, so 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 runs 74.9% on time across 2,443 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 2,444 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.
Work out the risk of missing a connection in DEN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 83.6% on time and June 69.7%, a swing of 14 points. If the dates move at all, move them out of June before you think about anything else. 2,418 completed flights over 12 months sit behind that.
Common questions
MIA to DEN questions
How often is MIA to DEN delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.2% of the 2,444 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on MIA to DEN?
United Airlines leads at 83.0% on time across 877 flights. American Airlines is at the other end on 76.1%, a gap of 7 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 MIA to DEN?
The 5am–8am departure window is the strongest at 89.7% on time. The 2pm–5pm window is the weakest at 64.5%, 25 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 June delays on MIA to DEN?
June is the weakest month at 69.7% on time, compared with 83.6% in February. Across the year that is 14 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 MIA — the return legseparate record
- Miami International (MIA) delay statistics
- Denver International (DEN) delay statistics
- Frontier Airlines on MIA to DEN83.2%
- United Airlines on MIA to DEN83.0%
- American Airlines on MIA to DEN76.1%
- Southwest Airlines on MIA to DEN54.5%
- MIA to ATL, a related route74.2%
- PHX to DEN, a related route76.7%
- MIA to LGA, a related route67.4%
- Frontier Airlines on-time record83.2%
- United Airlines on-time record83.0%
- American Airlines on-time record76.1%
- 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. MIA to DEN and DEN to MIA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.