Route reliability record
IAH→MIA
Houston to Miami
- Flights
- 3,665
- Period
- September 2025 to August 2026
- Distance
- 964 mi
- Carriers
- 6
This route lands a B, about a point better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 3,665 IAH to MIA flights, of which United Airlines flew 1,438 at 82.0% on time.
Best time to fly IAH to MIA: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 90.1% of the time and Wednesday flights 84.5%, against 78.6% 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
78.6%
Arrivals under 15 minutes late, of 3,611 completed flights
Avg delay
93 min
Across delayed arrivals only, not all flights
Cancelled
1.28%
National rate is 1.89%
Best carrier
United
82.0% on time across 1,438 flights
These figures cover 3,665 flights between September 2025 and August 2026. Beyond the headline rate, 8.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on IAH to MIA
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,438 | 82.0% | 57 min | 0.28% | B+ |
| American Airlines | 1,565 | 78.8% | 114 min | 1.21% | B |
| Envoy Airthin sample | 129 | 78.3% | 51 min | 0.00% | B+ |
| Frontier Airlinesthin sample | 196 | 69.0% | 170 min | 6.12% | C− |
| Spirit Airlinesthin sample | 323 | 68.8% | 81 min | 3.72% | C− |
| Republic Airwaysthin sample | 14 | 64.3% | 173 min | 0.00% | D+ |
No carrier stands out. United tops the table at 82.0%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on IAH to MIA
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 Houston to Miami
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. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAH → FLLHouston to Fort Lauderdale | United Airlines | 85.1% | 85.6% | 0.58% | 5am–8am, Tue | UA 2261 07:20 |
| 2. IAH → MIAHouston to Miami | United Airlines | 81.8% | 82.0% | 0.28% | 5am–8am, Tue | UA 410 12:00 |
| 3. IAH → MIAHouston to Miami | American Airlines | 77.8% | 78.8% | 1.21% | 5am–8am, Wed | AA 1347 07:30 |
| 4. IAH → FLLHouston to Fort Lauderdale | Spirit Airlines | 69.5% | 70.9% | 1.99% | 5am–8am, Tue | — |
| 5. HOU → FLLHouston to Fort Lauderdale | Southwest Airlines | 64.8% | 65.0% | 0.37% | 8am–11am, Tue | — |
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 22 points, against 3 points between the best and worst carrier.
- 5am–8am1,076 flights90.1%
- 8am–11am345 flights79.9%
- 11am–2pm652 flights80.0%
- 2pm–5pm504 flights72.3%
- 5pm–8pm938 flights68.9%
- 8pm–5am150 flights68.6%
Scale runs 60% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.1% of the time, against 68.6% for the overnight window. That is 22 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 1,076 flights scheduled in it.
Explore
Filter IAH to MIA 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 IAH to MIA, the best departure window is 5am–8am at 90.1% on time and the worst is 8pm–5am at 68.6%, a wide gap of 21.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.1%
- 8–11am79.9%
- 11am–2pm80.0%
- 2–5pm72.3%
- 5–8pm68.9%
- 8pm–5am68.6%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 15 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.
October is the best month on the calendar at 83.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 341 flights.
Across the week, Wednesday is the strongest day at 84.5% on time and Sunday the weakest at 71.3%, a spread of 13 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 43% of the 72,000 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Late-arriving aircraft
- 35%Carrier
- 17%National Airspace System
- 6%Extreme weather
- 0%Security
43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 72,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 71,609 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 25,000 of the 72,000 delay minutes reported here.
Cancellations sit at 1.28% against a national 1.89%, which is ordinary. Diversions add another 0.19%.
Connections and stage length
What a delay here actually costs
8.1% 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 an hour and a half, which a normal layover absorbs.
The 964 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.
The return leg runs 78.8% on time across 3,667 flights, within half a point 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 3,665 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 MIA 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. October runs 83.8% on time and March 68.6%, a swing of 15 points. If the dates move at all, move them out of March before you think about anything else. 3,611 completed flights over 12 months sit behind that.
Common questions
IAH to MIA questions
How often is IAH to MIA delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.4% of the 3,665 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on IAH to MIA?
United Airlines leads at 82.0% on time across 1,438 flights. American Airlines is at the other end on 78.8%, a gap of 3 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 IAH to MIA?
The 5am–8am departure window is the strongest at 90.1% on time. The 8pm–5am window is the weakest at 68.6%, 22 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 March delays on IAH to MIA?
March is the weakest month at 68.6% on time, compared with 83.8% in October. Across the year that is 15 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
- MIA to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Miami International (MIA) delay statistics
- United Airlines on IAH to MIA82.0%
- American Airlines on IAH to MIA78.8%
- Envoy Air on IAH to MIA78.3%
- Frontier Airlines on IAH to MIA69.0%
- Spirit Airlines on IAH to MIA68.8%
- IAH to ORD, a related route75.1%
- ATL to MIA, a related route71.2%
- IAH to DFW, a related route76.4%
- United Airlines on-time record82.0%
- American Airlines on-time record78.8%
- Envoy Air on-time record78.3%
- 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. IAH to MIA and MIA to IAH 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.