Route reliability record
LAS→IAH
Las Vegas to Houston
- Flights
- 3,411
- Period
- September 2025 to August 2026
- Distance
- 1,222 mi
- Carriers
- 3
This route earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 3,411 LAS to IAH flights, of which United Airlines flew 2,596 at 85.8% on time.
Best time to fly LAS to IAH: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 93.2% of the time and Wednesday flights 89.9%, against 84.2% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 85.8% on time across 2,596 flights.
Key figures
On time
84.2%
Arrivals under 15 minutes late, of 3,371 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.89%
Best carrier
United
85.8% on time across 2,596 flights
These figures cover 3,411 flights between September 2025 and August 2026. The median arrival is 9 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 LAS to IAH
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.8% of the time; Frontier Airlines manages 78.0%. Sample sizes sit next to every figure, because a two-point gap across 409 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,596 | 85.8% | 74 min | 0.35% | A+ |
| Spirit Airlines | 406 | 79.9% | 111 min | 2.96% | B |
| Frontier Airlines | 409 | 78.0% | 66 min | 1.96% | B |
United leads Frontier by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on LAS to IAH
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 Las Vegas to Houston
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. 1 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LAS → IAHLas Vegas to Houston | United Airlines | 85.5% | 85.8% | 0.35% | 5am–8am, Wed | UA 2608 06:00 |
| 2. LAS → IAHLas Vegas to Houston | Spirit Airlines | 77.5% | 79.9% | 2.96% | 8am–11am, Wed | — |
| 3. LAS → IAHLas Vegas to Houston | Frontier Airlines | 76.5% | 78.0% | 1.96% | 5am–8am, Wed | — |
| 4. LAS → HOULas Vegas to Houston | Southwest Airlines | 72.4% | 72.7% | 0.40% | 5am–8am, 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 19 points, against 8 points between the best and worst carrier.
- 5am–8am491 flights93.2%
- 8am–11am880 flights88.8%
- 11am–2pm612 flights78.4%
- 2pm–5pm710 flights74.7%
- 5pm–8pm183 flights83.4%
- 8pm–5am535 flights88.1%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.2% of the time, against 74.7% for the afternoon 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 8am–11am window is the busiest, with 880 flights scheduled in it.
Explore
Filter LAS to IAH 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 LAS to IAH, the best departure window is 5am–8am at 93.2% on time and the worst is 2pm–5pm at 74.7%, a wide gap of 18.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am93.2%
- 8–11am88.8%
- 11am–2pm78.4%
- 2–5pm74.7%
- 5–8pm83.4%
- 8pm–5am88.1%
best all US flightsScale 60% to 100%.
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.
Delays peak in March, when the on-time rate falls to 77.7%. December is the strongest month at 91.6%. Moving a flexible trip across that boundary buys 14 points. March was the busiest month here, with 323 flights.
Across the week, Wednesday is the strongest day at 89.9% on time and Monday the weakest at 79.7%, a spread of 10 points.
Delay causes
Why this route gets delayed
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 42,000 reported delay minutes.
- 38%Carrier
- 35%Late-arriving aircraft
- 24%National Airspace System
- 2%Extreme weather
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 42,000 reported delay minutes here, that single category outweighs weather by 19 to one. The split is drawn from 41,637 reported delay minutes.
The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 16,000 of the 42,000 delay minutes reported here.
Cancellations are rare at 0.85%, 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
5.7% 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 a little over an hour, which a normal layover absorbs.
The 1,222 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 82.8% on time across 3,409 flights, within about 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 3,411 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 IAH 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. December runs 91.6% on time and March 77.7%, a swing of 14 points. If the dates move at all, move them out of March before you think about anything else. 3,371 completed flights over 12 months sit behind that.
Common questions
LAS to IAH questions
How often is LAS to IAH delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.8% of the 3,411 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on LAS to IAH?
United Airlines leads at 85.8% on time across 2,596 flights. Frontier Airlines is at the other end on 78.0%, a gap of 8 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 LAS to IAH?
The 5am–8am departure window is the strongest at 93.2% on time. The 2pm–5pm window is the weakest at 74.7%, 19 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 LAS to IAH?
March is the weakest month at 77.7% on time, compared with 91.6% in December. 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
- IAH to LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on LAS to IAH85.8%
- Spirit Airlines on LAS to IAH79.9%
- Frontier Airlines on LAS to IAH78.0%
- LAS to LAX, a related route77.9%
- ORD to IAH, a related route76.0%
- LAS to DEN, a related route76.5%
- United Airlines on-time record85.8%
- Spirit Airlines on-time record79.9%
- Frontier Airlines on-time record78.0%
- 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. LAS to IAH and IAH to LAS 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.