Route reliability record
DEN→MEM
Denver to Memphis
- Flights
- 1,333
- Period
- July 2025 to June 2026
- Distance
- 872 mi
- Carriers
- 4
This route sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,333 DEN to MEM flights, of which United Airlines flew 728 at 81.0% on time.
Best time to fly DEN to MEM: a 11am–2pm departure, ideally on a Wednesday. Flights in that window arrived on time 85.3% of the time and Wednesday flights 80.8%, against 75.7% 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
75.7%
Arrivals under 15 minutes late, of 1,321 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.81%
Best carrier
United
81.0% on time across 728 flights
These figures cover 1,333 flights between July 2025 and June 2026. Beyond the headline rate, 8.6% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on DEN to MEM
The choice of carrier is not cosmetic here. United Airlines arrives on time 81.0% of the time; Southwest Airlines manages 65.3%. Sample sizes sit next to every figure, because a two-point gap across 465 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Frontier Airlinesthin sample | 139 | 82.6% | 61 min | 0.72% | B+ |
| United Airlines | 728 | 81.0% | 73 min | 0.82% | B+ |
| Southwest Airlines | 465 | 65.3% | 60 min | 0.86% | C+ |
The spread between United and Southwest is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.
Flight by flight
Flights on DEN to MEM
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.
Best ways to make this trip
The most reliable ways to fly Denver to Memphis
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. DEN → MEMDenver to Memphis | United Airlines | 80.3% | 81.0% | 0.82% | 11am–2pm, Sun | UA 2130 17:25 |
| 2. DEN → MEMDenver to Memphis | Southwest Airlines | 64.7% | 65.3% | 0.86% | 2pm–5pm, Wed | — |
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 40 points, against 16 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1 flights—
- 8am–11am178 flights80.3%
- 11am–2pm373 flights85.3%
- 2pm–5pm188 flights84.0%
- 5pm–8pm524 flights68.3%
- 8pm–5am69 flights44.9%
Scale runs 35% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 44.9% on time, against 85.3% for the 11am–2pm 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 5pm–8pm window is the busiest, with 524 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 47 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.
July is the worst month at 47.1% on time, 47 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 Friday the weakest at 67.9%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 59% of the 21,000 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.
- 59%Late-arriving aircraft
- 30%Carrier
- 10%National Airspace System
- 1%Extreme weather
59% 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 21,000 reported delay minutes here, that single category outweighs weather by 51 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 21,042 reported delay minutes.
Cancellations are rare at 0.83%, 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 actually costs
8.6% 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 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 78.8% on time across 1,333 flights, 3 points above 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 MEM 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 July 47.1%, a swing of 47 points. If the dates move at all, move them out of July before you think about anything else. 1,321 completed flights over 12 months sit behind that.
Common questions
DEN to MEM questions
How often is DEN to MEM 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 24.3% of the 1,333 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to MEM?
United Airlines leads at 81.0% on time across 728 flights. Southwest Airlines is at the other end on 65.3%, a gap of 16 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 DEN to MEM?
The 11am–2pm departure window is the strongest at 85.3% on time. The 8pm–5am window is the weakest at 44.9%, 40 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 July delays on DEN to MEM?
July is the weakest month at 47.1% on time, compared with 94.1% in November. Across the year that is 47 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
- MEM to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Frontier Airlines on DEN to MEM82.6%
- United Airlines on DEN to MEM81.0%
- Southwest Airlines on DEN to MEM65.3%
- DEN to PHX, a related route75.7%
- ATL to MEM, a related route82.3%
- DEN to SLC, a related route77.5%
- SkyWest Airlines on-time record100.0%
- Frontier Airlines on-time record82.6%
- United Airlines on-time record81.0%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. DEN to MEM and MEM to DEN 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.