Carrier route record
UADEN→BOI
United Airlines · Denver to Boise
- Flights
- 946
- Period
- July 2025 to June 2026
- Share of route
- 31%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on DEN to BOI lands a B+, 2 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 946 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 874 at 78.7% on time.
The US average over the same twelve months is 77.6%, so there is little to separate United on DEN to BOI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.2%
Arrivals under 15 minutes late, of 942 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.81%
Whole route
76.3%
Every carrier on DEN to BOI, 3,039 flights
These figures cover 946 flights between July 2025 and June 2026. The median arrival is 2 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 DEN to BOI
United flew 946 of the 3,039 flights on DEN to BOI, about 31% of it. Its 79.2% on time is 3 points better than the route as a whole, which runs 76.3%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 79.2% to Southwest at 71.5%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 78.7% of the time; Southwest Airlines manages 71.5%. Sample sizes sit next to every figure, because a two-point gap across 1,093 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 946 | 79.2% | 57 min | 0.32% | B+ |
| SkyWest Airlines | 874 | 78.7% | 71 min | 0.11% | B+ |
| Frontier Airlinesthin sample | 126 | 78.6% | 39 min | 0.00% | B+ |
| Southwest Airlines | 1,093 | 71.5% | 46 min | 0.18% | C+ |
SkyWest leads Southwest by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
United flight numbers on DEN to BOI
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 31 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am128 flights93.8%
- 8am–11am—
- 11am–2pm365 flights85.4%
- 2pm–5pm90 flights63.3%
- 5pm–8pm363 flights71.7%
- 8pm–5am—
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.8% of the time, against 63.3% for the afternoon 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 11am–2pm window is the busiest, with 365 flights scheduled in it.
Across the year
United on DEN to BOI through the year
June is the worst month at 65.8% on time, 26 points below November, the best at 91.5%. 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. July was the busiest month here, with 123 flights.
Across the week, Sunday is the strongest day at 84.6% on time and Thursday the weakest at 76.8%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 11,000 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.
- 50%Late-arriving aircraft
- 30%Carrier
- 17%National Airspace System
- 3%Extreme weather
50% 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 11,000 reported delay minutes here, that single category outweighs weather by 17 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 11,118 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 93.8% on time here.
Cancellations are rare at 0.32%, 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
6.2% 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 649 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 runs 80.1% on time across 946 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.
One caution: this is a thin sample. 946 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on DEN to BOI
Put together: treat all of this as provisional. 946 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 79.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 942 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to BOI, every carrier
- United on BOI to DEN, the return leg
- SkyWest Airlines on DEN to BOI78.7%
- Frontier Airlines on DEN to BOI78.6%
- Southwest Airlines on DEN to BOI71.5%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.