First day of last period
Cycle length
Result (click to copy)
Frequently Asked Questions
When do I ovulate?
Ovulation typically occurs 14 days before your next period, regardless of cycle length. For a 28-day cycle: day 14. For a 32-day cycle: day 18. The fertile window is 5 days before ovulation plus the day of ovulation itself.
What is the fertile window?
The fertile window is the 6 days during which pregnancy is possible: the 5 days before ovulation and the day of ovulation itself. Sperm can survive up to 5 days in the reproductive tract, while an egg survives 12-24 hours after release.
How accurate is this calculator?
This calculator assumes regular cycles. Irregular cycles, stress, illness, PCOS, and other factors affect ovulation timing. For accurate tracking, use basal body temperature (BBT) monitoring or ovulation predictor kits (OPKs) alongside this calculator.