Period Calculator
Predict your next period date and track your menstrual cycle.
Upcoming Periods
How to Use
Enter the first day of your last period, your average cycle length and period duration. Click Calculate to see your next period date and upcoming cycles.
How Period Dates Are Predicted
The next period is estimated by adding your average cycle length to the first day of your last period. This assumes regular cycles. Irregular cycles may produce less accurate predictions.
Frequently Asked Questions
How accurate is this calculator?
Predictions are based on average cycle length and assume regular cycles. Stress, illness, travel and hormonal changes can affect cycle timing. Use this as a general guide, not an exact predictor.
Can I use this to calculate safe days?
This calculator should not be relied upon for contraception. Cycle variations mean there are no guaranteed "safe" days. Consult a healthcare provider for family planning advice.