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DelayAtlas

Carrier route record

UADENORD

United Airlines · Denver to Chicago

Flights
3,756
Period
July 2025 to June 2026
Share of route
61%
Carriers
5
C+GRADE

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.

United on DEN to ORD sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 3,756 flights. The strongest carrier on the route with a full sample, American Airlines, flew 1,469 at 73.0% on time.

The national on-time rate over the same period is 77.6%, so United on DEN to ORD runs 6 points behind the country as a whole. Across a thousand flights that is about 62 extra late arrivals.

Key figures

On time

71.4%

Arrivals under 15 minutes late, of 3,711 completed flights

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

0.75%

National rate is 1.81%

Whole route

71.1%

Every carrier on DEN to ORD, 6,161 flights

These figures cover 3,756 flights between July 2025 and June 2026. Beyond the headline rate, 10.4% 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

United against every carrier on DEN to ORD

United flew 3,756 of the 6,161 flights on DEN to ORD, most of the route. Its 71.4% on time is about level with the route as a whole at 71.1%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from Envoy at 74.0% to Southwest at 63.7%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. American Airlines arrives on time 73.0% of the time; Southwest Airlines manages 63.7%. Sample sizes sit next to every figure, because a two-point gap across 482 flights means less than a ten-point one.

On-time performance by carrier on DEN to ORD
AirlineFlightsOn timeAvg delayCancelledGrade
Envoy Airthin sample12574.0%60 min0.80%C+
American Airlines1,46973.0%124 min2.04%C
United Airlines (this page)3,75671.4%79 min0.75%C+
Frontier Airlinesthin sample32968.6%96 min1.22%C
Southwest Airlines48263.7%63 min0.62%D+

American leads Southwest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

United flight numbers on DEN to ORD

Departure window

When United runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

  • 5am–8am626 flights87.4%
  • 8am–11am521 flights82.7%
  • 11am–2pm730 flights72.4%
  • 2pm–5pm786 flights58.6%
  • 5pm–8pm689 flights58.9%
  • 8pm–5am404 flights76.7%

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 87.4% of the time, against 58.6% for the afternoon window. That is 29 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 786 flights scheduled in it.

Across the year

United on DEN to ORD through the year

On-time rate by calendar month73J77F69M75A79M68J55J64A78S75O72N72D
Darker means more delays. Figures are on-time percentages.May best, July worst

July is the worst month at 55.2% on time, 24 points below May, the best at 79.1%. 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. May was the busiest month here, with 370 flights.

Across the week, Tuesday is the strongest day at 74.1% on time and Sunday the weakest at 68.1%. 6 points is a smaller lever than departure hour, but it is free.

On-time rate by day of the week71.2Mon74.1Tue72.2Wed69.0Thu71.5Fri74.0Sat68.1Sun
Monday: 71.2 percent on time. Tuesday: 74.1 percent on time. Wednesday: 72.2 percent on time. Thursday: 69.0 percent on time. Friday: 71.5 percent on time. Saturday: 74.0 percent on time. Sunday: 68.1 percent on time

Delay causes

Why United runs late on this route

One category carries most of the weight here. National Airspace System accounts for 44% of the 83,000 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.

  • National Airspace System
    44%
  • Late-arriving aircraft
    34%
  • Carrier
    18%
  • Extreme weather
    4%

44% 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 36,000 minutes out of 83,000, against a national NAS share of 21%. The split is drawn from 83,203 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 87.4% on time here.

Cancellations are rare at 0.75%, 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 costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.4% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 888 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 77.4% on time across 3,758 flights, 6 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 6 points of difference.

The sample behind these figures is 3,756 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 United on DEN to ORD

Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 79.1% on time and July 55.2%, a swing of 24 points. If the dates move at all, move them out of July before you think about anything else. 3,711 completed flights over 12 months sit behind that.

Related

Where to go next

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.