Track your menstrual cycle, predict next period, ovulation day, and fertility window.
This calculator provides estimates based on average cycle data. Actual cycles may vary. Consult a healthcare provider for medical advice.
Enter the start date of your last period and your average cycle and period lengths. Click "Calculate" to see predictions for your next period, ovulation day, fertility window, current cycle phase, and estimated due date if pregnant. The calculator uses standard formulas: ovulation is typically 14 days before the next period, and the fertile window is 5 days before ovulation plus ovulation day.