Route reliability record
MEM→DEN
Memphis to Denver
- Flights
- 1,395
- Period
- September 2025 to August 2026
- Distance
- 872 mi
- Carriers
- 4
This route lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 1,395 MEM to DEN flights, of which United Airlines flew 727 at 81.6% on time.
Best time to fly MEM to DEN: a 5am–8am departure, ideally on a Friday. Flights in that window arrived on time 90.2% of the time and Friday flights 80.1%, against 77.7% 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
77.7%
Arrivals under 15 minutes late, of 1,380 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.89%
Best carrier
United
81.6% on time across 727 flights
These figures cover 1,395 flights between September 2025 and August 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on MEM to DEN
The choice of carrier is not cosmetic here. United Airlines arrives on time 81.6% of the time; Southwest Airlines manages 72.8%. Sample sizes sit next to every figure, because a two-point gap across 522 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+ |
| United Airlines | 727 | 81.6% | 81 min | 0.96% | B+ |
| Frontier Airlinesthin sample | 145 | 75.5% | 89 min | 0.69% | B+ |
| Southwest Airlines | 522 | 72.8% | 58 min | 0.57% | C+ |
United leads Southwest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 | 80.8% | 81.6% | 0.96% | 8am–11am, Fri | — |
| 2. MEM → DENMemphis to Denver | Southwest Airlines | 72.4% | 72.8% | 0.57% | 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 46 points, against 9 points between the best and worst carrier.
- 5am–8am176 flights90.2%
- 8am–11am508 flights87.7%
- 11am–2pm29 flights—
- 2pm–5pm397 flights74.6%
- 5pm–8pm194 flights44.0%
- 8pm–5am91 flights81.3%
Scale runs 35% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 44.0% on time, against 90.2% 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 508 flights scheduled in it.
Explore
Filter MEM 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 MEM to DEN, the best departure window is 5am–8am at 90.2% on time and the worst is 5pm–8pm at 44.0%, a wide gap of 46.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.2%
- 8–11am87.7%
- 11am–2pm—
- 2–5pm74.6%
- 5–8pm44.0%
- 8pm–5am81.3%
best all US flightsScale 35% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 32 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 62.1% on time, 32 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. August was the busiest month here, with 134 flights.
The day of the week is close to irrelevant here: 4 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
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 22,000 reported delay minutes.
- 40%National Airspace System
- 28%Carrier
- 26%Late-arriving aircraft
- 6%Extreme weather
- 0%Security
40% 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 8,732 minutes out of 22,000, against a national NAS share of 21%. The split is drawn from 22,034 reported delay minutes.
Cancellations are rare at 0.79%, 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
7.8% 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 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.
The return leg runs 76.4% on time across 1,395 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 1,395 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 August 62.1%, a swing of 32 points. If the dates move at all, move them out of August before you think about anything else. 1,380 completed flights over 12 months sit behind that.
Common questions
MEM to DEN questions
How often is MEM to DEN delayed?
Roughly 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 22.3% of the 1,395 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 MEM to DEN?
United Airlines leads at 81.6% on time across 727 flights. Southwest Airlines is at the other end on 72.8%, a gap of 9 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 90.2% on time. The 5pm–8pm window is the weakest at 44.0%, 46 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 MEM to DEN?
August is the weakest month at 62.1% on time, compared with 94.1% in November. Across the year that is 32 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
- Memphis International (MEM) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on MEM to DEN81.6%
- Frontier Airlines on MEM to DEN75.5%
- Southwest Airlines on MEM to DEN72.8%
- MEM to ATL, a related route86.2%
- PHX to DEN, a related route76.7%
- MEM to ORD, a related route74.8%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record81.6%
- Frontier Airlines on-time record75.5%
- 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. 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.
Embed MEM to DEN’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.