The Schengen 90/180 rule, worked through on real dates
The 90 days do not reset on 1 January, and they do not reset when you leave. Here is what the rolling 180-day window actually does, with the arithmetic shown.
Most explanations of the Schengen rule stop at "90 days in any 180". That sentence is correct and almost useless, because it does not tell you the one thing you need: which 180 days.
The window moves with you
The rule is not an annual allowance. It does not reset on 1 January, on the anniversary of your first entry, or when you fly home. Instead, on every single day of your stay, the authorities can look back over the previous 180 days — including that day — and add up the days you spent inside the area. That total must never exceed 90.
Because the window is measured backwards from today, it slides forward one day at a time. A day you spent in Lisbon drops out of the calculation exactly 180 days after it happened, and not before.
A worked example
Say you are standing at a border on 5 September 2026.
Count back 180 days, including 5 September itself, and the window starts on 10 March 2026. Any day you spent in the Schengen area between 10 March and 5 September counts. Anything before 10 March is invisible to this calculation.
Now suppose you took one trip: you arrived on 1 June 2026 and left on 20 June 2026.
- Both the entry day and the exit day count as full days.
- 1 June to 20 June inclusive is 20 days.
- 20 of your 90 are used. 70 days remain as at 5 September.
The Schengen 90/180 Calculator does this for a whole travel history at once, and shows the window it used.
Where people get it wrong
"I left, so the clock reset." It did not. Leaving stops you accruing days. It does not give any back. The days you already spent stay in the window until they age out, 180 days after each one.
"I only count full days, not the day I arrived." Both ends count. A trip from Monday to Wednesday is three days, not one. This is the single most common error, and it runs in the direction that gets people refused entry.
"The 90 days are per country." They are not. The allowance is shared across the entire Schengen area. Five days in Spain plus five in Germany is ten days used, not five and five.
"My days come back all at once." They come back one at a time. If you used 90 days in a single block, you do not get 90 fresh days on any one date — you get one day back for each day that falls out of the window, starting 180 days after your first day in.
What this rule does not cover
The 90/180 rule governs short stays. National long-stay visas and residence permits sit outside it entirely, and time spent on one of those is not counted the same way. It also says nothing about whether you need a visa in the first place — that depends on your nationality, which DAYOZA does not determine.
Source: European Commission — Short-stay calculator, and Regulation (EU) 2016/399 (Schengen Borders Code), Article 6.
Before you travel: DAYOZA provides informational calculations based on the rules and sources available on this page. Immigration and entry requirements can change. Always verify your eligibility and permitted stay with the relevant official authority before traveling.