Period & Ovulation Calculator
Predict your next period, ovulation day, and fertile window from your last period.
Your Cycle
Predictions assume a regular cycle. Cycles vary. This is an estimate, not contraception or medical advice.
About your cycle
Ovulation usually happens about 14 days before your next period. The fertile window is the few days around it.
Tracking your cycle helps whether you're trying to conceive or avoiding pregnancy.
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Period calculator FAQ
How is my next period predicted?
By adding your cycle length to the first day of your last period.
When do I ovulate?
Typically about 14 days before your next period.
My period is irregular — what now?
Predictions are less reliable; see a doctor if cycles are very irregular.