Does my planned stay in Switzerland conform to 90/180-day travel rules?

Question

I am a Canadian citizen studying in Canada. As part of my graduate degree, I am completing an informal research stay (no taking classes or working) in Switzerland. I stayed in Switzerland already from Aug 8 to Nov 5, 2024, under short-stay entry for Canadian citizens. I plan to return for another 90-day stay as soon as I legally can.

This Schengen calculator and this one both say this is a legal stay (see images below), but I know these results aren't a 100% guarantee and I want to avoid overstays/fines.

This is the scenario I'm worried about: if I enter on Feb 15, my time spent in Schengen between Aug 19 and Nov 5 (79 days) still counts towards my 90/180 day restriction. So by this logic, on the day of my arrival, I would have only 11 remaining days in Schengen (Feb 15 - Feb 26) even though the number of days/180-day period "freezes" at 79 as each day advances (again, see images). I'm worried that border control officers might require proof that I'll leave Schengen by Feb 26.

Can you confirm that I and the calculator are interpreting Schengen visa requirements correctly and that I'd be within regulations if I began my next 90-day stay in Switzerland on Feb 15?

Answer 1

The Schengen Borders code was amended several time to make this clear. The current English-language wording is

For intended stays on the territory of the Member States of a duration of no more than 90 days in any 180-day period, which entails considering the 180-day period preceding each day of stay

You have to consider each day in turn, one-by-one. The number of days available on February 15 doesn't matter as such, you only need one. Then on February 16, you consider the preceding 180-day period (which is off by one day compared to the period you looked at on February 15) and you see if you still have one day left, etc.

Incidentally, the main risk is not an overstay or fine but being (incorrectly) denied entry.