Estimate your most fertile days and ovulation date based on your menstrual cycle length and the first day of your last period.
What is the "fertile window"?
The fertile window is the time in your menstrual cycle when pregnancy is possible. It typically includes the five days leading up to ovulation and the day of ovulation itself. Sperm can survive in the female reproductive tract for up to five days, so intercourse during this window gives the highest chance of conception.
Is this calculator a reliable method of birth control?
Absolutely not. This calculator is an estimation tool for conception purposes only. Cycle lengths can vary, and ovulation can be unpredictable. It should never be used as a method of contraception.