Period Calculator

This calculator estimates future period dates based on your average cycle length and last period start date.

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How to Use

Enter the start date of your last period and your average cycle length. The calculator predicts the dates of your next several periods along with estimated fertile windows. Save or copy the schedule so you can plan ahead and track changes over time.

Common Use Cases

• •Predicting the date of your next period
• •Tracking cycle length over time
• •Planning around your fertile window
• •Preparing for travel and events in advance
• •Monitoring cycle regularity