The rule in one sentence
On any day you are in the Schengen area, the number of days you have spent there in the 180-day period ending on that day must be 90 or fewer.
Step by step
- Pick a date to check — usually today, or the last day of a planned trip.
- Count back 179 days. The window is that date plus the 179 days before it: 180 days in total.
- Count every day you were in any Schengen country inside that window. Arrival and departure days each count as a full day.
- Compare with 90. 90 or fewer is compliant; 91 or more is an overstay.
- Repeat for every day of a future trip. The window moves daily, so a trip must be compliant on each of its days, not just the first.
Rolling window vs calendar year
A common mistake is to think you get "90 days per half-year" that resets on 1 January and 1 July. There is no reset date. Each day you spend drops out of the window individually, exactly 180 days later. Someone who spent all of March in Spain gets those 31 days back gradually through late August and September.
Worked example
You stay in France from 1 January to 31 March (90 days). On 31 March you've used 90/90 and must leave. The 1 January day leaves your window on 30 June, so the earliest you can return is 30 June — and then only for one day unless more days have expired. Your full allowance returns on 27 September.
Why "45 in, 45 out" can still fail
Alternating patterns look safe but drift. Always test the exact dates in the trip planner.
What does not count
- Days in Ireland, Cyprus, the UK, Turkey, the Balkans outside Schengen (e.g. Albania, Serbia, Montenegro).
- Days covered by a national long-stay visa or residence permit for that country.
- Airside transit in a Schengen airport without passing passport control.
See the full calculation methodology.