1.6 How to calculate the 90 days period
The Schengen Visa allows the holder a total stay of maximum 90 days within 180 days. If you are planning a stay for longer than 90 days (e.g. study in Germany, long-term medical, family reunion) then please contact the German Embassy directly to apply for a residence permit Email: kuwa%27%diplo%27%de,info
If you hold a multiple entry Schengen Visa, you may leave and return any number of times within the 180-day period, but the combined stay within the Schengen States must not total more than 90 days. Important is the date of the actual entry, not the beginning of the visa validity.
A clearer definition of short stay of non-EU citizens in the Schengen area ("90 days in any 180 days period") is applicable from 18 October 2013. Since then a new method of calculation of short stays applies – please find a calculator tool on the homepage of the EU Commission that might assist you to calculate your periods of stay: https://ec.europa.eu/assets/home/visa-calculator/calculator.htm?lang=en