Route reliability record
BWI→DEN
Baltimore to Denver
- Flights
- 2,784
- Period
- September 2025 to August 2026
- Distance
- 1,491 mi
- Carriers
- 3
This route lands a B, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That rests on 2,784 BWI to DEN flights, of which United Airlines flew 840 at 84.5% on time.
Best time to fly BWI to DEN: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 86.3% of the time and Tuesday flights 80.5%, against 76.0% for the route overall.
The US average over the same twelve months is 77.3%, 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
76.0%
Arrivals under 15 minutes late, of 2,729 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
1.40%
National rate is 1.89%
Best carrier
United
84.5% on time across 840 flights
These figures cover 2,784 flights between September 2025 and August 2026. The median arrival is 3 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 BWI to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 84.5% of the time; Southwest Airlines manages 72.2%. Sample sizes sit next to every figure, because a two-point gap across 1,919 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 840 | 84.5% | 61 min | 0.48% | B+ |
| Southwest Airlines | 1,919 | 72.2% | 50 min | 1.82% | C |
| Frontier Airlinesthin sample | 25 | 72.0% | 51 min | 0.00% | C+ |
The spread between United and Southwest is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
Flight by flight
Flights on BWI 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 Baltimore to Denver
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. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BWI → DENBaltimore to Denver | United Airlines | 84.1% | 84.5% | 0.48% | 8am–11am, Tue | UA 2412 08:30 |
| 2. IAD → DENWashington to Denver | United Airlines | 83.7% | 84.1% | 0.50% | 5am–8am, Tue | UA 1587 12:48 |
| 3. IAD → DENWashington to Denver | Southwest Airlines | 77.6% | 78.4% | 1.01% | 5am–8am, Sat | — |
| 4. DCA → DENWashington to Denver | Frontier Airlines | 77.3% | 78.1% | 1.02% | 11am–2pm, Sat | F9 685 07:00 |
| 5. BWI → DENBaltimore to Denver | Southwest Airlines | 70.9% | 72.2% | 1.82% | 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 24 points, against 12 points between the best and worst carrier.
- 5am–8am364 flights85.2%
- 8am–11am855 flights86.3%
- 11am–2pm263 flights69.4%
- 2pm–5pm743 flights70.8%
- 5pm–8pm405 flights64.5%
- 8pm–5am154 flights62.2%
Scale runs 55% to 90%.
The 8pm–5am window is where this operation falls apart: 62.2% on time, against 86.3% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 855 flights scheduled in it.
Explore
Filter BWI 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 BWI to DEN, the best departure window is 8am–11am at 86.3% on time and the worst is 8pm–5am at 62.2%, a wide gap of 24.1 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am85.2%
- 8–11am86.3%
- 11am–2pm69.4%
- 2–5pm70.8%
- 5–8pm64.5%
- 8pm–5am62.2%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 27 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.
December is the weak month at 61.9% on time, against 89.2% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 269 flights.
Across the week, Tuesday is the strongest day at 80.5% on time and Wednesday the weakest at 73.5%, a spread of 7 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 34,000 reported delay minutes.
- 34%National Airspace System
- 31%Late-arriving aircraft
- 30%Carrier
- 4%Extreme weather
- 1%Security
34% 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 11,000 minutes out of 34,000, against a national NAS share of 21%. The split is drawn from 34,251 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 86.3% on time here.
Cancellations sit at 1.40% against a national 1.89%, which is ordinary. Diversions add another 0.57%.
Connections and stage length
What a delay here actually costs
6.3% 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 roughly 50 minutes, which a normal layover absorbs.
The 1,491 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 77.3% on time across 2,781 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 2,784 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. October runs 89.2% on time and December 61.9%, a swing of 27 points. If the dates move at all, move them out of December before you think about anything else. 2,729 completed flights over 12 months sit behind that.
Common questions
BWI to DEN questions
How often is BWI to DEN delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.0% of the 2,784 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 50 minutes on average.
Which airline is most reliable on BWI to DEN?
United Airlines leads at 84.5% on time across 840 flights. Southwest Airlines is at the other end on 72.2%, a gap of 12 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 BWI to DEN?
The 8am–11am departure window is the strongest at 86.3% on time. The 8pm–5am window is the weakest at 62.2%, 24 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 December delays on BWI to DEN?
December is the weakest month at 61.9% on time, compared with 89.2% in October. Across the year that is 27 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 BWI — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on BWI to DEN84.5%
- Southwest Airlines on BWI to DEN72.2%
- BWI to ATL, a related route79.9%
- PHX to DEN, a related route76.7%
- BWI to MCO, a related route75.5%
- United Airlines on-time record84.5%
- Southwest Airlines on-time record72.2%
- Frontier Airlines on-time record72.0%
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.05 million flight records
Direction matters. BWI to DEN and DEN to BWI 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.