Route reliability record
CLE→DEN
Cleveland to Denver
- Flights
- 1,845
- Period
- September 2025 to August 2026
- Distance
- 1,201 mi
- Carriers
- 3
This route lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,845 CLE to DEN flights, of which United Airlines flew 940 at 87.5% on time.
Best time to fly CLE to DEN: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 93.3% of the time and Saturday flights 87.1%, against 82.4% for the route overall.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.3%. That gap is worth roughly 51 fewer late arrivals for every thousand flights.
Key figures
On time
82.4%
Arrivals under 15 minutes late, of 1,827 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
0.54%
National rate is 1.89%
Best carrier
United
87.5% on time across 940 flights
These figures cover 1,845 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 CLE to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 87.5% of the time; Southwest Airlines manages 76.9%. Sample sizes sit next to every figure, because a two-point gap across 609 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 940 | 87.5% | 69 min | 0.11% | A+ |
| Frontier Airlinesthin sample | 296 | 77.3% | 59 min | 1.69% | B |
| Southwest Airlines | 609 | 76.9% | 60 min | 0.66% | B+ |
United leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on CLE 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 Cleveland 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. CLE → DENCleveland to Denver | United Airlines | 87.4% | 87.5% | 0.11% | 8am–11am, Sat | UA 690 08:30 |
| 2. CLE → DENCleveland to Denver | Southwest Airlines | 76.4% | 76.9% | 0.66% | 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 36 points, against 11 points between the best and worst carrier.
- 5am–8am302 flights93.3%
- 8am–11am436 flights91.7%
- 11am–2pm343 flights88.0%
- 2pm–5pm401 flights80.7%
- 5pm–8pm284 flights57.6%
- 8pm–5am79 flights61.0%
Scale runs 50% to 100%.
The 5pm–8pm window is where this operation falls apart: 57.6% on time, against 93.3% for the 5am–8am 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 436 flights scheduled in it.
Explore
Filter CLE 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 CLE to DEN, the best departure window is 5am–8am at 93.3% on time and the worst is 5pm–8pm at 57.6%, a wide gap of 35.7 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am93.3%
- 8–11am91.7%
- 11am–2pm88.0%
- 2–5pm80.7%
- 5–8pm57.6%
- 8pm–5am61.0%
best all US flightsScale 50% to 100%.
Across the year
When delays peak on this route
This route's year swings by 13 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 76.4% on time, 13 points below November, the best at 89.4%. 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 185 flights.
Across the week, Saturday is the strongest day at 87.1% on time and Monday the weakest at 79.2%, a spread of 8 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 20,000 reported delay minutes.
- 40%Late-arriving aircraft
- 31%National Airspace System
- 26%Carrier
- 2%Extreme weather
- 0%Security
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 20,000 reported delay minutes here, that single category outweighs weather by 17 to one. The split is drawn from 20,322 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 93.3% on time here.
Cancellations are rare at 0.54%, 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
5.8% 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 about an hour, which a normal layover absorbs.
The 1,201 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 75.9% on time across 1,847 flights, 7 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 7 points of difference.
The sample behind these figures is 1,845 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. November runs 89.4% on time and August 76.4%, a swing of 13 points. If the dates move at all, move them out of August before you think about anything else. 1,827 completed flights over 12 months sit behind that.
Common questions
CLE to DEN questions
How often is CLE to DEN 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 17.6% of the 1,845 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on CLE to DEN?
United Airlines leads at 87.5% on time across 940 flights. Southwest Airlines is at the other end on 76.9%, a gap of 11 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 CLE to DEN?
The 5am–8am departure window is the strongest at 93.3% on time. The 5pm–8pm window is the weakest at 57.6%, 36 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 CLE to DEN?
August is the weakest month at 76.4% on time, compared with 89.4% in November. Across the year that is 13 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 CLE — the return legseparate record
- Cleveland Hopkins International (CLE) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on CLE to DEN87.5%
- Frontier Airlines on CLE to DEN77.3%
- Southwest Airlines on CLE to DEN76.9%
- CLE to ORD, a related route74.5%
- PHX to DEN, a related route76.7%
- CLE to ATL, a related route84.6%
- United Airlines on-time record87.5%
- Frontier Airlines on-time record77.3%
- Southwest Airlines on-time record76.9%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. CLE to DEN and DEN to CLE 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.