Use this free calculator to estimate your next period, your likely ovulation day and your most fertile window. Enter the first day of your last period and your typical cycle length, and we’ll do the rest. Results are estimates based on cycle averages — they are not a substitute for medical advice or a reliable form of contraception.
Please enter the first day of your last period.
Next period
Estimated ovulation
~14 days before next period
Fertile window
Highest chance of conception
Your next three cycles
| Cycle | Period starts | Fertile window | Ovulation |
|---|
These dates are estimates based on the averages you entered and typical cycle patterns. Individual cycles vary. This tool is for general information only and should not be used as a method of contraception or as a substitute for professional medical advice.