Estimate your most fertile days and next expected period based on your average cycle length.
Ovulation is when an ovary releases an egg, typically once per menstrual cycle. It usually happens about 14 days before your next period starts. The days leading up to and including ovulation form your "fertile window," when pregnancy is most likely.
Ovulation Day = First Day of Last Period + (Cycle Length - 14)
Fertile Window = 5 days before ovulation through 1 day after
If your last period started on the 1st of the month with a 28-day cycle, ovulation is estimated around day 14, with a fertile window roughly from day 9 to day 15.
This is an estimate for general information only and isn't a substitute for medical advice or a fertility tracking method reviewed by a doctor.
By counting back from the next expected period, since ovulation usually occurs about 14 days before.
They're estimates — actual timing can vary cycle to cycle, especially with irregular cycles.
The several-day span around ovulation when conception is most likely.