Route reliability record
MEM→DEN
Memphis to Denver
- Flights
- 1,333
- Period
- July 2025 to June 2026
- Distance
- 872 mi
- Carriers
- 4
This route lands a B+, about a point 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,333 MEM to DEN flights, of which United Airlines flew 728 at 81.2% on time.
Best time to fly MEM to DEN: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 89.8% of the time and Wednesday flights 80.8%, against 78.8% 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
78.8%
Arrivals under 15 minutes late, of 1,317 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.90%
National rate is 1.81%
Best carrier
United
81.2% on time across 728 flights
These figures cover 1,333 flights between July 2025 and June 2026. The median arrival is 6 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 MEM to DEN
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 728 | 81.2% | 79 min | 1.10% | B |
| Southwest Airlines | 465 | 76.3% | 56 min | 0.65% | B+ |
| Frontier Airlinesthin sample | 139 | 74.6% | 95 min | 0.72% | C+ |
No carrier stands out. United tops the table at 81.2%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Best ways to make this trip
The most reliable ways to fly Memphis 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. MEM → DENMemphis to Denver | United Airlines | 80.3% | 81.2% | 1.10% | 8am–11am, Wed | — |
| 2. MEM → DENMemphis to Denver | Southwest Airlines | 75.8% | 76.3% | 0.65% | 5am–8am, Mon | — |
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 42 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am168 flights89.8%
- 8am–11am480 flights86.5%
- 11am–2pm61 flights81.7%
- 2pm–5pm402 flights74.2%
- 5pm–8pm135 flights48.1%
- 8pm–5am87 flights82.8%
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 48.1% on time, against 89.8% 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 480 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 31 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.
June is the worst month at 63.3% on time, 31 points below November, the best at 94.1%. 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. March was the busiest month here, with 129 flights.
Across the week, Wednesday is the strongest day at 80.8% on time and Thursday the weakest at 75.8%. 5 points is a smaller lever than departure hour, but it is free.
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.
- 31%Late-arriving aircraft
- 31%National Airspace System
- 30%Carrier
- 8%Extreme weather
- 0%Security
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 89.8% on time here. The split is drawn from 19,983 reported delay minutes.
No single cause dominates. late-arriving aircraft at 31%, national airspace system at 31% and carrier at 30% split the 20,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations sit at 0.90% against a national 1.81%, which is ordinary. Diversions add another 0.30%.
Connections and stage length
What a delay here actually costs
7.3% 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 a little over an hour, which a normal layover absorbs.
The 872 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 75.7% on time across 1,333 flights, 3 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 3 points of difference.
The sample behind these figures is 1,333 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 94.1% on time and June 63.3%, a swing of 31 points. If the dates move at all, move them out of June before you think about anything else. 1,317 completed flights over 12 months sit behind that.
Common questions
MEM to DEN questions
How often is MEM to DEN 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 21.2% of the 1,333 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on MEM to DEN?
United Airlines leads at 81.2% on time across 728 flights. Southwest Airlines is at the other end on 76.3%, a gap of 5 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 MEM to DEN?
The 5am–8am departure window is the strongest at 89.8% on time. The 5pm–8pm window is the weakest at 48.1%, 42 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 June delays on MEM to DEN?
June is the weakest month at 63.3% on time, compared with 94.1% in November. Across the year that is 31 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 MEM — the return legseparate record
- Denver International (DEN) delay statistics
- United Airlines on MEM to DEN81.2%
- Southwest Airlines on MEM to DEN76.3%
- Frontier Airlines on MEM to DEN74.6%
- MEM to ATL, a related route87.4%
- PHX to DEN, a related route77.2%
- MEM to ORD, a related route76.0%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record81.2%
- Southwest Airlines on-time record76.3%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. MEM to DEN and DEN to MEM 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.