Layover, counted in hours you can actually use

An itinerary counts a layover from scheduled landing to scheduled departure. For a session, what matters is the smaller number inside it: the hours you are actually in a room.

What comes off first

Taxiing to the stand, leaving the aircraft, the walk along the pier, border control if you are entering Schengen, the baggage belt if your case is not tagged through, and the ride to the hotel. On the way back, the ride, security, outbound border control if you are leaving Schengen, and the margin the airline wants before the gate closes. On a six hour layover these often add up to three hours or more.

What fits in what is left

Under four scheduled hours, a session rarely fits. Between four and six, a single hour usually does, with enough slack left for the walk back to departures. Between six and ten, ninety minutes or two hours fits with time to shower and dress without hurry. A layover that crosses a night is a different kind of booking, closer to a hotel stay than a stop. The page on massage between flights sets out the subtraction in full.

Whether you can leave at all

Some passengers cannot leave the transit area on a given ticket or passport, and for them a session on that layover is not possible. The transit area entry explains the distinction, and it is worth checking before anything else.

When the stop shrinks

A late inbound eats into a layover from the front, while the onward departure seldom moves to make room for it. If the stop gets shorter before she has set out, a line in the thread can turn a longer booking into a single hour, or slide the start later inside the hours that remain. After she has left for the airport, a cancellation leaves the whole deposit with the house unless another guest takes the hour, so a delay is worth reporting as soon as the aircraft wifi comes on rather than once the plane reaches the stand.