Predict your upcoming period dates and estimated fertile window based on your last period and average cycle length.
This tool predicts upcoming menstrual period dates and an estimated fertile window based on your cycle history.
Future periods are predicted by adding your average cycle length repeatedly to your last period start date. The fertile window is estimated around ovulation, roughly 14 days before the next period.
Enter the start date of your most recent period and your typical cycle length, then click Calculate.
Example: With a 28 day cycle starting on a given date, the next period is predicted 28 days later, and the fertile window falls roughly 12 to 16 days after the last period start.
How accurate are these predictions. They are estimates based on averages; actual cycles can vary due to stress, health, and other factors.
Is this a reliable form of contraception. No, this tool is for general awareness only and should not be relied upon for contraception.