Route reliability record
BOI→LAS
Boise to Las Vegas
- Flights
- 1,401
- Period
- July 2025 to June 2026
- Distance
- 519 mi
- Carriers
- 5
This route lands a B+, 4 points better than the national rate of 77.6%. About one flight in five 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 1,401 BOI to LAS flights, with a median arrival 7 minutes early.
Best time to fly BOI to LAS: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 97.2% of the time and Saturday flights 87.8%, against 81.1% for the route overall.
The US average over the same twelve months is 77.6%, 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
81.1%
Arrivals under 15 minutes late, of 1,399 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.14%
National rate is 1.81%
Best carrier
Southwest
81.6% on time across 1,050 flights
These figures cover 1,401 flights between July 2025 and June 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.
Carrier by carrier
Which airline is most reliable on BOI to LAS
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 |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 71 | 91.5% | 86 min | 0.00% | A+ |
| Southwest Airlines | 1,050 | 81.6% | 53 min | 0.19% | B+ |
| SkyWest Airlinesthin sample | 219 | 80.8% | 57 min | 0.00% | B+ |
| Spirit Airlinesthin sample | 47 | 66.0% | 71 min | 0.00% | C+ |
| Allegiant Airthin sample | 14 | 50.0% | 165 min | 0.00% | F+ |
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 31 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–8am395 flights97.2%
- 8am–11am71 flights97.2%
- 11am–2pm306 flights77.5%
- 2pm–5pm182 flights78.6%
- 5pm–8pm330 flights68.4%
- 8pm–5am117 flights66.7%
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 97.2% of the time, against 66.7% for the overnight window. That is 31 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 395 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 17 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 September, when the on-time rate falls to 73.7%. January is the strongest month at 90.5%. Moving a flexible trip across that boundary buys 17 points. July was the busiest month here, with 127 flights.
Across the week, Saturday is the strongest day at 87.8% on time and Friday the weakest at 73.4%. 14 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 15,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 53%Late-arriving aircraft
- 26%National Airspace System
- 17%Carrier
- 5%Extreme weather
53% 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 15,000 reported delay minutes here, that single category outweighs weather by 12 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 15,496 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 97.2% on time here.
Cancellations are rare at 0.14%, 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 actually 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 about an hour, which a normal layover absorbs.
The 519 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 73.3% on time across 1,400 flights, 8 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 8 points of difference.
The sample behind these figures is 1,401 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 LAS 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. January runs 90.5% on time and September 73.7%, a swing of 17 points. If the dates move at all, move them out of September before you think about anything else. 1,399 completed flights over 12 months sit behind that.
Common questions
BOI to LAS questions
How often is BOI to LAS 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 18.9% of the 1,401 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is BOI to LAS compared with the rest of the country?
81.1% of flights arrive on time here against a national 77.6%, a difference of 4 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on BOI to LAS?
The 5am–8am departure window is the strongest at 97.2% on time. The 8pm–5am window is the weakest at 66.7%, 31 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 September delays on BOI to LAS?
September is the weakest month at 73.7% on time, compared with 90.5% in January. Across the year that is 17 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
- LAS to BOI — the return legseparate record
- Harry Reid International (LAS) delay statistics
- Southwest Airlines on BOI to LAS81.6%
- SkyWest Airlines on BOI to LAS80.8%
- BOI to SEA, a related route85.7%
- LAX to LAS, a related route76.5%
- BOI to DEN, a related route80.9%
- Alaska Airlines on-time record91.5%
- Southwest Airlines on-time record81.6%
- SkyWest Airlines on-time record80.8%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. BOI to LAS and LAS to BOI 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.