Numbers from Aug 2025 – Jul 2026 flight records · generated 1 October 2026
GateCast grades your connection from A to F on how likely you are to make it, using a year of real flight records. At Chicago O'Hare, pairs of United flights scheduled 45–59 minutes apart were missed on 15% of the days they ran, Aug 2025 – Jul 2026; pairs 90–120 minutes apart, on 6%.
How often United connections here were missed
Every pair of United flights at Chicago O'Hare (regional flights sold as United included), grouped by the scheduled time between them, and checked against what actually happened on each day both flights ran, Aug 2025 – Jul 2026.
"Missed" means the first flight was cancelled, or arrived too late to leave about 31 minutes to get off, reach the next gate and board before the doors close. That time is our estimate for United connections here: flight records don't say which passengers made their connection. Days when the second flight was cancelled aren't counted. Pairs scheduled less than 35 minutes apart are left out, because we can't tell which of those the airline would sell as a connection.
When United connections at Chicago O'Hare go wrong
From the same flight records as the chart above, and with the same meaning of "missed".
How long a connection to look for
United connections of 60–89 minutes here were missed on 9% of days. No shorter connection time in the chart above was missed on fewer than 1 day in 10.
Time of day
United connections of 45–59 minutes at Chicago O'Hare were missed on 11% of days when the first flight was due in before 10:00, and on 24% when it was due in at 18:00 or later.
| First flight due in | 35–44 min | 45–59 min | 60–89 min | 90–120 min |
|---|---|---|---|---|
| before 10:00 | 19% | 11% | 7% | 5% |
| 10:00–13:59 | 18% | 12% | 7% | 5% |
| 14:00–17:59 | 24% | 16% | 10% | 6% |
| 18:00 or later | 35% | 24% | 15% | 10% |
Share of days missed, by scheduled arrival time (Chicago O'Hare local time) and scheduled time between the flights. "—": fewer than 500 days to go on.
Time of year
The month with the most missed United connections at Chicago O'Hare was March 2026: 13% of days. The fewest was September 2025: 6%. The first flight was cancelled or diverted most often in March 2026, on 3.5% of days, against 0.3% in October 2025.
| Month | Days missed | First flight cancelled |
|---|---|---|
| Aug 2025 | 9% | 1.9% |
| Sep 2025 | 6% | 0.4% |
| Oct 2025 | 7% | 0.3% |
| Nov 2025 | 13% | 2.5% |
| Dec 2025 | 12% | 1.1% |
| Jan 2026 | 12% | 2.9% |
| Feb 2026 | 7% | 0.9% |
| Mar 2026 | 13% | 3.5% |
| Apr 2026 | 12% | 2.2% |
| May 2026 | 9% | 1.1% |
| Jun 2026 | 12% | 1.8% |
| Jul 2026 | 13% | 3.0% |
"First flight cancelled" includes flights diverted to another airport. "—": fewer than 500 days to go on.
The last flight of the day
Of United's scheduled flights leaving Chicago O'Hare at 18:00 or later, 57 of 174 are its last flight of the day to that city: miss the connection and the next United flight there leaves the next day. Before 10:00 it is 2 of 167. Connections onto a last flight of the day were missed on 14% of days; connections with a later United flight to the same city, on 10%.
How late United flights into Chicago O'Hare ran
Over 90,334 scheduled United flights into Chicago O'Hare, Aug 2025 – Jul 2026, 24% arrived 15 or more minutes late and 9% an hour or more late. The typical flight arrived at the gate 4 minutes early. 2.3% were cancelled or diverted.
What decides a connection at Chicago O'Hare
- Between Terminals 1, 3 and 5, a Terminal Transfer Bus runs behind security every 15 minutes from 11:30 to 21:30 for passengers with a same-day boarding pass. Outside those hours the only way between them is the ATS train outside security, then screening again.Chicago Department of Aviation, Transportation Between Terminals (flychicago.com), checked 23 September 2026
- At Chicago O'Hare, half of travellers arriving from abroad without Global Entry waited 15 minutes or less at passport control, and 1 in 10 waited more than 39 minutes (24 September 2025 – 23 September 2026).US Customs and Border Protection, Airport Wait Times (awt.cbp.gov), 24 September 2025 – 23 September 2026, checked 25 September 2026
- All international arrivals at Chicago O'Hare collect their checked bags, clear US customs, check them in again and go back through security before the next flight. The exception is flights that clear US preclearance before they leave. It runs at 16 airports (ten in Canada, including Toronto, Montreal and Vancouver, plus Dublin, Shannon, Nassau, Bermuda, Aruba and Abu Dhabi), though not on every flight from them; a flight that clears it arrives at Chicago O'Hare as a domestic flight. Your airline can tell you whether yours does.US Customs and Border Protection, "Checking my baggage through to my final destination" (help.cbp.gov, article 1244); TSA, "One Stop Security" pilot release, 27 August 2025 (tsa.gov); US Customs and Border Protection, Preclearance locations and hours (cbp.gov/travel/preclearance, last modified 24 June 2026); Aer Lingus, "US immigration and pre-clearance" (mediacentre.aerlingus.com: no preclearance on its late Dublin departures to New York and Boston), checked 1 October 2026
What real connections here look like
Real United connections at Chicago O'Hare from last year's flights. Each is the typical case of its kind, not the worst we found. Schedules change, so these exact flights may not run on your date.
44 minutes between flights looks tight — but on 87% of the 218 days both flights ran, the first one got in with enough time for a typical connection here. Graded B.
Graded over the 218 days both flights ran, Aug 2025 – Jul 2026 · generated 1 October 2026 · local times
1h 15m looks like plenty of time. But the first flight arrived more than an hour late on 28% of the 67 days both flights ran, and the connection was missed on 18% of them. Graded D.
Graded over the 67 days both flights ran, Aug 2025 – Jul 2026 · generated 1 October 2026 · local times
3h 20m between flights looks like plenty of room. But this is the last United flight of the day from ORD to ONT: miss it, and there's no later one that day, however long the wait was. The first flight got in too late on 2 of the 66 days both flights ran. Graded D; with another United flight an hour later it would be C.
Graded over the 66 days both flights ran, Aug 2025 – Jul 2026 · generated 1 October 2026 · local times
These are two separate tickets, not one booking. If the first flight runs late and you miss the second, you're not owed a seat on it. Passengers typically paid $222* one way from ORD to PHX. Graded A.
Graded over the 101 days both flights ran, Aug 2025 – Jul 2026 · generated 1 October 2026 · local times
Typical fare passengers paid, one way, per ticket, from the US DOT fare survey (Jul 2024–Jun 2025). Fare only; bags and seats extra. Today's price may be different.
Check your own flights
Connecting through Chicago O'Hare on different flights? Enter both flight numbers and the date.
Questions
Is 45 minutes enough for United at Chicago O'Hare?
Over Aug 2025 – Jul 2026, pairs of United flights at Chicago O'Hare scheduled 45–59 minutes apart were missed on 15% of the days they ran (5,274 flight pairs). Your own two flights can be much better or worse than that, so check them rather than going on the minutes alone.
Is an hour enough for United at Chicago O'Hare?
Over Aug 2025 – Jul 2026, pairs of United flights at Chicago O'Hare scheduled 60–89 minutes apart were missed on 9% of the days they ran (14,605 flight pairs). Your own two flights can be much better or worse than that, so check them rather than going on the minutes alone.
- Chicago Department of Aviation, Transportation Between Terminals (flychicago.com), checked 23 September 2026
- US Customs and Border Protection, Airport Wait Times (awt.cbp.gov), 24 September 2025 – 23 September 2026, checked 25 September 2026
- US Customs and Border Protection, "Checking my baggage through to my final destination" (help.cbp.gov, article 1244); TSA, "One Stop Security" pilot release, 27 August 2025 (tsa.gov); US Customs and Border Protection, Preclearance locations and hours (cbp.gov/travel/preclearance, last modified 24 June 2026); Aer Lingus, "US immigration and pre-clearance" (mediacentre.aerlingus.com: no preclearance on its late Dublin departures to New York and Boston), checked 1 October 2026
- Flight times, delays and cancellations: US Department of Transportation, Bureau of Transportation Statistics, On-Time Performance, Aug 2025 – Jul 2026
- Fares: US DOT fare survey (DB1B), Jul 2024-Jun 2025
Grades are estimates, not guarantees. Always check your airline's minimum connection time.
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