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Health Tools

Period calculator

Predict when your next periods are likely to begin, based on the first day of your last period and your average cycle length.

Select the date your most recent period started.

Usually between 20 and 45 days. The average is 28.

How many days your period usually lasts.

Frequently asked questions

How does the period calculator work?

It predicts the start dates of your next periods by adding your average cycle length to the first day of your last period, repeated across the coming months.

How accurate are period predictions?

They are estimates based on a regular cycle. If your cycles are irregular the real dates may differ. Tracking your actual periods over time improves accuracy.

Can I use this to plan or avoid pregnancy?

No. This calculator is for information only and must not be used as a conception aid or a method of contraception. Speak to a healthcare professional about family planning.

Is the information I enter private?

Yes. The calculation runs entirely in your browser. Evecare never sees, stores, or transmits anything you enter.