Carrier route record
UAMIA→IAH
United Airlines · Miami to Houston
- Flights
- 1,479
- Period
- July 2025 to June 2026
- Share of route
- 40%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on MIA to IAH earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 1,479 flights. The strongest carrier on the route with a full sample, American Airlines, flew 1,527 at 70.1% on time.
Set against the rest of the country, United's MIA to IAH record is 8 points better than the US average of 77.6%. That gap is worth roughly 83 fewer late arrivals for every thousand flights.
Key figures
On time
85.9%
Arrivals under 15 minutes late, of 1,467 completed flights
Avg delay
91 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.81%
Whole route
77.2%
Every carrier on MIA to IAH, 3,737 flights
These figures cover 1,479 flights between July 2025 and June 2026. The median arrival is 14 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 IAH
United flew 1,479 of the 3,737 flights on MIA to IAH, about 40% of it. Its 85.9% on time is 9 points better than the route as a whole, which runs 77.2%. Ranked by on-time rate it is number two of six carriers on the route, where the range runs from Envoy at 86.9% to Republic at 64.3%. Three of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: half a point 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 |
|---|---|---|---|---|---|
| Envoy Airthin sample | 122 | 86.9% | 39 min | 0.00% | A+ |
| United Airlines (this page) | 1,479 | 85.9% | 91 min | 0.61% | A+ |
| Frontier Airlinesthin sample | 155 | 78.4% | 97 min | 1.29% | B |
| American Airlines | 1,527 | 70.1% | 72 min | 1.24% | C |
| Spirit Airlines | 440 | 69.7% | 87 min | 2.73% | C |
| Republic Airwaysthin sample | 14 | 64.3% | 133 min | 0.00% | D+ |
No carrier stands out. American tops the table at 70.1%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.
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 24 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–8am296 flights95.3%
- 8am–11am371 flights91.6%
- 11am–2pm450 flights86.4%
- 2pm–5pm113 flights73.9%
- 5pm–8pm247 flights70.9%
- 8pm–5am2 flights—
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.3% of the time, against 70.9% for the evening window. That is 24 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 450 flights scheduled in it.
Across the year
United on MIA to IAH through the year
August is the worst month at 72.5% on time, 22 points below October, the best at 94.4%. 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 147 flights.
Across the week, Monday is the strongest day at 88.7% on time and Sunday the weakest at 81.6%. 7 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 19,000 reported delay minutes.
- 32%Carrier
- 32%Late-arriving aircraft
- 30%National Airspace System
- 7%Extreme weather
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 95.3% on time here. The split is drawn from 18,904 reported delay minutes.
No single cause dominates. carrier at 32%, late-arriving aircraft at 32% and national airspace system at 30% split the 19,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations are rare at 0.61%, 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
5.9% 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 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 80.3% on time across 1,479 flights, 6 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 6 points of difference.
The sample behind these figures is 1,479 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.
What to do with this
Booking United on MIA to IAH
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 94.4% on time and August 72.5%, a swing of 22 points. If the dates move at all, move them out of August before you think about anything else. 1,467 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to IAH, every carrier
- United on IAH to MIA, the return leg
- Envoy Air on MIA to IAH86.9%
- Frontier Airlines on MIA to IAH78.4%
- American Airlines on MIA to IAH70.1%
- Spirit Airlines on MIA to IAH69.7%
- United Airlines network-wide record
- Miami International (MIA) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.