Period Calculator

Track menstrual cycle. Predict ovulation and next period.

Cycle Details

Last Period

Cycle Length

days

Note

Cycle Forecast

Ready Desc

About this calculator

Overview

Average cycle 28 days. Ovulation ~day 14. Track start dates. Predict next period and fertile window. Irregular cycles need more data.

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Pro Tips

Fun Facts

Formula: Next period = Last start + Average cycle length. Ovulation = Period − 14.