A 45-minute connection is about 30 usable minutes, because the door closes roughly 15 minutes before departure. At big US hubs that was enough for a change within the same concourse in about 88% of the flight pairs I checked, and for a change to a far concourse in about 79%. In the evening, those numbers drop to 83% and 72%.
So 45 minutes is fine in the morning, on one ticket, with a later flight behind it if things go wrong. I wouldn’t book it on the last flight of the day.
What 45 minutes contains
The clock on your itinerary runs from scheduled arrival to scheduled departure. Three things take bites out of it.
The gate cutoff is about 15 minutes. Delta and United both say to be at the gate 15 minutes before departure.
Getting off takes longer than it feels like it should. From row 25 of a 737 or A320 at a typical load, the estimate is about 8 to 11 minutes after the door opens. From row 5, it’s about 2 to 4. Those come from a model fit to timed flights, so treat them as ranges.
Then there’s the walk. Two gates in one concourse can be 5 minutes apart. Atlanta is the classic stretch: from public map data, a Concourse E gate is about 17 to 29 minutes from the terminal curb, train included, and a Concourse T gate is about 6 to 11. Going from T to E therefore costs something like 11 to 18 minutes. That’s an estimate from walking speeds and maps, and nobody timed it with a stopwatch.
Add it up and you get two working numbers.
| Change of plane | Door | Off the plane | Walk | You need |
|---|---|---|---|---|
| Same concourse, mid-cabin | 15 min | About 8 min | About 2 to 5 min | About 25 min |
| Far concourse, back of the plane | 15 min | About 10 min | About 15 min | About 40 min |
Twenty-five and forty are my rounding, and they’re the two thresholds used below.
What actually happens to the 45 minutes
Schedules have padding, so a flight usually reaches the gate early, and the next one often leaves a little late. A 45-minute connection therefore tends to run longer than 45 minutes. The trouble is the tail.
Using public flight records, I paired every arrival and departure by one airline at each of 19 airline hubs, on the same day, with a scheduled gap of about 45 minutes, across the 12 months to August 2026. That makes about 5.2 million possible connections. For each I measured the real time from gate arrival to gate departure.
| Scheduled gap | Median real gap | Under 25 min | Under 40 min |
|---|---|---|---|
| 45 min | 56 min | 12% | 21% |
| 60 min | 70 min | 8% | 12% |
| 90 min | 101 min | 5% | 6% |
| 120 min | 132 min | 3% | 4% |
Going from 45 minutes to 60 nearly halves the far-concourse failures. Going from 90 to 120 buys much less. The first 15 extra minutes do the most.
The hour matters as much as the airport. Here are the 45-minute pairs by when the first flight was due in.
| Scheduled arrival | Under 25 min | Under 40 min |
|---|---|---|
| Before noon | 8% | 17% |
| Noon to 4:59 PM | 11% | 20% |
| 5 PM or later | 17% | 28% |
Airports differ too.
| Airline and hub | Under 25 min | Under 40 min |
|---|---|---|
| Southwest, Baltimore | 8% | 19% |
| Delta, Atlanta | 10% | 19% |
| United, Denver | 11% | 20% |
| American, Charlotte | 12% | 20% |
| American, Dallas-Fort Worth | 14% | 22% |
| United, O’Hare | 14% | 27% |
| United, San Francisco | 22% | 36% |
Atlanta’s reputation for size doesn’t show up here, because Delta’s flights there tend to arrive early: 74% of the inbound flights in those pairs reached the gate ahead of schedule. San Francisco stands out, and these records can’t say why.
One local detail: a tracker’s “landed” isn’t the gate. Taxi-in at O’Hare has a median of 18 minutes and a 90th percentile of 36, and at the 7 PM hour those rise to 23 and 52. The real-gap numbers above already include taxi time, but your own watch doesn’t. Sitting on the ramp at O’Hare with 20 minutes left isn’t yet a missed connection. The taxi-in table has the figure for your hub.
What this can’t show
These are possible connections, not real passengers. The records don’t show who was on board, whether an airline held a flight for connecting passengers, or whether a gate agent reopened a door. Cancelled flights are left out, which flatters every row. Only flights with the same operating airline are paired, so regional feeders aren’t included, and domestic flights only.
International arrivals are a separate case. Coming into the US from abroad, you clear passport control, collect your bag, recheck it and go through security again. I’d want 90 minutes there at the least, and that’s judgement, since nobody publishes the chain.
Two things worth doing
Book the gap, then pick the seat. If a 45-minute connection is the only option, a seat near the front is worth more than a window: row 25 costs you about 6 minutes against row 5.
Keep it on one ticket. Airlines don’t promise that you’ll make a connection (Delta’s and Southwest’s contracts both say so), but Delta’s rule on missed connections, for one, rebooks you or refunds the unused part. On two tickets nobody has checked the gap, and the rebooking is between you and the second airline. Minimum connection time explains what the booking system was checking when it sold you the gap, boarding time vs departure time covers how close to departure the door really closes, and how long it takes to get off the plane has the row-by-row detail.
Skycap keeps both flights as one trip and shows the minutes left between them. It names the gates and any change of terminal once the airline has set them, and says when the gap looks tight. How connections work
Walking estimates use public map data.