In many countries, you can stay without a visa or residence permit for a duration of 90 days. In a lot of cases, this duration is reset after 180 days have passed. It is often hard to calculate this using a calendar alone. You can get a rough estimate by counting the days you have spent in the country in question in the last 6 month. Usually, the number of days you are allowed to stay is calculated on the date of entry and does not reset thereafter. Additional information on this matter at least in the case of the Schengen-area can be found at schengenvisainfo.com, but the calculator on this website does not work very well.
This app helps people calculate the number of days during multiple stays and get a sum of days they have spent. The maximum number of days as well as the total duration in which days should be counted can be set (with the defaults being 90 within the last 180 days).
You can use this app at lsteinmann.shinyapps.io/DurationOfDays/.
This app is meant as guidance. I do not guarantee that this is correct or that your calculation will be accepted by the relevant authorities. When staying in a foreign country, always be sure to have a few 'days to spare' in case something unexpected happens, and be aware of the regulations.
For a proper assessment of your situation, always contact the relevant immigration authorities!