Period Calculator
Predict next period, ovulation, and fertile window based on your cycle.
Enter your details
Use the first day of your most recent period.
Used to estimate next period and ovulation timing.
Used to estimate the end date of your next period.
Tip: These are calendar estimates. Irregular cycles can reduce accuracy.
Results
Next period — start
Next period — end
Ovulation day (approx.)
Fertile window (approx.)
Educational use only — not medical advice. If your cycles are very irregular or you have concerns, consult a clinician.