Route reliability record
DEN→MDW
Denver to Chicago
- Flights
- 2,312
- Period
- July 2025 to June 2026
- Distance
- 895 mi
- Carriers
- 2
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 2,312 flights, with a median arrival 2 minutes early.
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
73.9%
Arrivals under 15 minutes late, of 2,256 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.86%
National rate is 1.81%
Best carrier
Southwest
74.0% on time across 2,218 flights
These figures cover 2,312 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% 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 MDW
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 2,218 | 74.0% | 57 min | 1.89% | C |
| Frontier Airlinesthin sample | 94 | 70.7% | 84 min | 1.06% | C |
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 half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am427 flights93.3%
- 8am–11am445 flights87.3%
- 11am–2pm430 flights79.5%
- 2pm–5pm350 flights71.1%
- 5pm–8pm431 flights52.0%
- 8pm–5am229 flights46.9%
Scale runs 40% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 46.9% 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 445 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 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 61.2% on time, 25 points below January, the best at 85.9%. 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 299 flights.
Across the week, Wednesday is the strongest day at 81.7% on time and Sunday the weakest at 67.8%. 14 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 48% of the 34,000 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.
- 48%Late-arriving aircraft
- 36%Carrier
- 15%National Airspace System
- 1%Extreme weather
- 0%Security
48% 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 34,000 reported delay minutes here, that single category outweighs weather by 38 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 34,169 reported delay minutes.
The largest share of delay minutes, 36%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 12,000 of the 34,000 delay minutes reported here.
Cancellations sit at 1.86% against a national 1.81%, which is ordinary. Diversions add another 0.56%.
Connections and stage length
What a delay here actually costs
8.2% 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 are the about an hour kind, which a normal layover absorbs.
The 895 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 runs 72.7% on time across 2,335 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 2,312 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.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 85.9% on time and June 61.2%, a swing of 25 points. If the dates move at all, move them out of June before you think about anything else. 2,256 completed flights over 12 months sit behind that.
Common questions
DEN to MDW questions
How often is DEN to MDW delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.1% of the 2,312 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is DEN to MDW compared with the rest of the country?
73.9% of flights arrive on time here against a national 77.6%, a difference of 4 points against it. That is worth a C on this site's grading scale.
What time of day has the fewest delays on DEN to MDW?
The 5am–8am departure window is the strongest at 93.3% on time. The 8pm–5am window is the weakest at 46.9%, 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 June delays on DEN to MDW?
June is the weakest month at 61.2% on time, compared with 85.9% in January. Across the year that is 25 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
- MDW to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Chicago Midway International (MDW) delay statistics
- Southwest Airlines on-time record74.0%
- Frontier Airlines on-time record70.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. DEN to MDW and MDW to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.