Period Calculator
Predict the date of your next few periods.
Result
Results are estimates for general information only and are not professional advice.
Predicting your period
By adding your cycle length to the first day of your last period, this calculator estimates the start dates of your next three periods, helping you plan ahead.
Frequently Asked Questions
What is the Period Calculator?
Predict the date of your next few periods. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the Period Calculator?
The Period Calculator asks for the following values (2): First day of last period, Cycle length (days). Fill them in and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the Period Calculator?
The Period Calculator uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the Period Calculator free, and do I need an account?
Yes. The Period Calculator — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.