How early should I actually arrive at the airport?

The airline's own guidance is the floor, and it is usually two hours before a short-haul departure and three before a long-haul one. Those figures exist because they account for the parts of the process the airline controls: bag drop cutoffs, which commonly close forty-five to sixty minutes before departure, and gate closure, typically fifteen to twenty minutes before.

Missing the bag drop cutoff means missing the flight even if the aircraft has not left, and this is the most common way people are denied boarding.

Adjust upward for conditions that add variance. Large or busy airports, peak holiday travel, early morning banks of departures, travelling with children, needing special assistance, oversized items, or flights where you must clear an additional security check. Some destinations impose extra screening that adds substantial time.

Adjust downward only when you have genuine information: travelling with hand luggage only, holding fast-track security access, and knowing the airport well. Even then, the saving is modest and the downside is total.

The asymmetry is what should drive the decision. Arriving an hour earlier than necessary costs an hour in a terminal. Arriving ten minutes too late costs the flight, the onward connection, and frequently the ticket, since missing a departure can invalidate subsequent segments on the same booking.

Many airports now publish live security queue times, and these are worth checking on the morning rather than relying on a general rule.

For international departures, remember that passport control and, in some cases, an exit process sit between security and the gate.