The Schengen zone consists of 26 countries in the EU with a border agreement allowing those exempt from social visit visa requirements to enter for a maximum of 90 days in any 180 day period. This specifically applies to US/CA/AU citizens and is somewhat troublesome to calculate. In trying to figure this out, I came across these utilities which might help: The official EU one, a less cluttered Visa Calculator, and an iOS app, 90 – Schengen.