Long enough to survive a late first flight, not just long enough to be allowed. Airlines will sell you the shortest connection the rules permit. Whether that is comfortable depends on the airport, the time of year and what happens if you miss it.
Minimum connection time is a floor, not a target
Every airport has a minimum connection time (MCT): the shortest layover an airline is allowed to sell on a single ticket. It varies with the airport, the terminals involved and whether the connection is domestic or international.
The MCT assumes your first flight lands on time and you walk straight to the next gate. It does not leave room for a late arrival, a slow taxi to the gate, a wait to deplane from the back of the aircraft, or a train between terminals. Treat it as the point where a connection stops being possible, not as a sensible plan.
Starting points
There is no single right number, but these are reasonable places to start on a single ticket. Add time for the factors in the next section.
| Connection | Suggested layover |
|---|---|
| Domestic, same terminal | 60 to 90 minutes |
| Domestic, large hub or change of terminal | 90 minutes or more |
| International to domestic, at your first US airport | 2 to 3 hours |
| Domestic to international | 2 hours or more |
Arriving from abroad takes longest. At the first US airport you land at, you go through passport control, collect any checked bags, clear customs, check the bags back in and go through security again before your next flight.
When to add more time
- Weather season at the connecting airport. Winter at northern hubs such as Chicago O'Hare, Minneapolis and Detroit; summer afternoons at Atlanta, Charlotte and Dallas Fort Worth. Each airport page has a planning tip.
- A first flight late in the day. It has had all day to pick up delays. See the best time of day to fly.
- The onward flight is the last of the day, or once a day. Missing it means an overnight stay. This matters most for international departures, for example from Dulles or Miami.
- You need more time to get around. Children, wheelchair assistance or a lot of carry-on luggage all slow down the walk between gates.
- The trip cannot slip. A wedding, a cruise departure or a first day at a new job is worth a longer layover or an earlier flight.
Separate tickets need far more
Everything above assumes both flights are on one ticket. Then, if you miss the connection, the airline rebooks you at no charge. On separate tickets, the second airline can treat you as a no-show, and you may need to collect and re-check your bags as well. Allow several hours, or an overnight stop if the second flight really matters. See one ticket or separate tickets.
Can a layover be too long?
Only in the sense that it costs you time. A longer layover does not protect you if the first flight is cancelled outright: then what matters is how many later flights there are. That is another reason to connect earlier in the day.
On the day: work out your real buffer
If your first flight is delayed, do the sum yourself: take the revised arrival time, add the airport's minimum connection time, and compare it with your onward departure. Whatever is left is your real buffer. If it has shrunk to almost nothing, ask the airline to move you to a later connection before your first flight even leaves, while there is still a choice of seats. There is more on this in tight layover: how to tell if you will make it and what happens if you miss a connecting flight.
This guide is general information for US travelers, not legal advice. Rules and airline commitments change; check with your airline or the US Department of Transportation for your specific situation.