Dawn Phase
Menstrual Cycle Calculator
Enter your last period date and average cycle length to predict your next period, ovulation, and fertile window.
Typically 21–35 days
How to use this calculator
Enter the first day of your last menstrual period (LMP) and your typical cycle length (usually 21–35 days). The calculator will estimate your next period, your ovulation day, and your 6-day fertile window.
Note: This tool provides estimates only and is not medical advice. Cycle lengths vary naturally. For family planning or health concerns, consult a healthcare provider.