Health Tools
Ovulation Calculator
First day of your last period & Average cycle length (days)
How is ovulation calculated?
Ovulation typically occurs about 14 days before your next menstrual period starts. If you have an average cycle length of 28 days, ovulation usually occurs on Day 14 of your cycle (with Day 1 being the first day of your period). If your cycle is longer, say 35 days, ovulation occurs around Day 21.
What is the fertile window?
Your fertile window represents the days in your menstrual cycle when pregnancy is possible. It spans 6 days in total: the 5 days leading up to ovulation, plus the day of ovulation itself. Sperm can survive inside the female reproductive tract for up to 5 days, whereas an egg survives for about 12 to 24 hours after release.