Route reliability record
BOI→DEN
Boise to Denver
- Flights
- 3,034
- Period
- September 2025 to August 2026
- Distance
- 649 mi
- Carriers
- 4
This route lands a B+, 4 points better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 3,034 BOI to DEN flights, of which SkyWest Airlines flew 895 at 86.6% on time.
Best time to fly BOI to DEN: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 92.6% of the time and Tuesday flights 85.4%, against 81.7% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 86.6% on time across 895 flights.
Key figures
On time
81.7%
Arrivals under 15 minutes late, of 3,018 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
0.13%
National rate is 1.89%
Best carrier
SkyWest
86.6% on time across 895 flights
These figures cover 3,034 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on BOI to DEN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 86.6% of the time; Southwest Airlines manages 78.4%. Sample sizes sit next to every figure, because a two-point gap across 1,088 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 895 | 86.6% | 93 min | 0.00% | A+ |
| Frontier Airlinesthin sample | 132 | 81.8% | 101 min | 0.00% | B+ |
| United Airlines | 919 | 80.7% | 103 min | 0.22% | B+ |
| Southwest Airlines | 1,088 | 78.4% | 58 min | 0.18% | B+ |
SkyWest leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on BOI to DEN
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 Boise to Denver
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BOI → DENBoise to Denver | SkyWest Airlines | 86.6% | 86.6% | 0.00% | 5am–8am, Wed | OO 5924 05:00 |
| 2. BOI → DENBoise to Denver | United Airlines | 80.5% | 80.7% | 0.22% | 8am–11am, Tue | UA 1782 06:30 |
| 3. BOI → DENBoise to Denver | Southwest Airlines | 78.3% | 78.4% | 0.18% | 5am–8am, Sat | — |
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 26 points, against 8 points between the best and worst carrier.
- 5am–8am932 flights92.6%
- 8am–11am632 flights89.4%
- 11am–2pm400 flights83.2%
- 2pm–5pm655 flights66.3%
- 5pm–8pm414 flights67.9%
- 8pm–5am1 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 92.6% of the time, against 66.3% for the afternoon window. That is 26 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 932 flights scheduled in it.
Explore
Filter BOI to DEN 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 BOI to DEN, the best departure window is 5am–8am at 92.6% on time and the worst is 2pm–5pm at 66.3%, a wide gap of 26.3 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.6%
- 8–11am89.4%
- 11am–2pm83.2%
- 2–5pm66.3%
- 5–8pm67.9%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
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.
August is the worst month at 73.7% on time, 17 points below January, the best at 90.2%. 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. May was the busiest month here, with 261 flights.
Across the week, Tuesday is the strongest day at 85.4% on time and Friday the weakest at 74.2%, a spread of 11 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 45,000 reported delay minutes.
- 37%Carrier
- 33%National Airspace System
- 28%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 17,000 of the 45,000 delay minutes reported here. The split is drawn from 45,247 reported delay minutes.
33% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 15,000 minutes out of 45,000, against a national NAS share of 21%.
Cancellations are rare at 0.13%, 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
6.8% 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 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.
The return leg is a different operation and performs like one: it runs 76.3% on time across 3,038 flights, 5 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 5 points of difference.
The sample behind these figures is 3,034 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 DEN 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 90.2% on time and August 73.7%, a swing of 17 points. If the dates move at all, move them out of August before you think about anything else. 3,018 completed flights over 12 months sit behind that.
Common questions
BOI to DEN questions
How often is BOI to DEN delayed?
Roughly 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 18.3% of the 3,034 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 BOI to DEN?
SkyWest Airlines leads at 86.6% on time across 895 flights. Southwest Airlines is at the other end on 78.4%, 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 BOI to DEN?
The 5am–8am departure window is the strongest at 92.6% on time. The 2pm–5pm window is the weakest at 66.3%, 26 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 August delays on BOI to DEN?
August is the weakest month at 73.7% on time, compared with 90.2% 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
- DEN to BOI — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on BOI to DEN86.6%
- Frontier Airlines on BOI to DEN81.8%
- United Airlines on BOI to DEN80.7%
- Southwest Airlines on BOI to DEN78.4%
- BOI to SEA, a related route84.9%
- PHX to DEN, a related route76.7%
- BOI to PHX, a related route84.2%
- SkyWest Airlines on-time record86.6%
- Frontier Airlines on-time record81.8%
- United Airlines on-time record80.7%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. BOI to DEN and DEN 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.