Ovulation & Fertile Window Calculator
Find your likely ovulation day and fertile window from the date of your last period and your usual cycle length, so you can plan with a clear picture.
How is ovulation calculated?
Ovulation usually happens about 14 days before your next period starts, not 14 days after the last one ended. The fertile window runs from roughly five days before ovulation to one day after, because sperm can survive up to five days. This is an estimate based on a regular cycle, and the day can shift from month to month.
This guide is for general information and reassurance — it isn't medical advice. Always follow your doctor or midwife for your own pregnancy.