Ovulation Calculator

What is a fertile window?

If you’re trying to fall pregnant, the timing of when you and your partner have intercourse is critical.

Your fertile window refers to the most fertile days in your menstrual cycle which give you the highest chance of conceiving.

If you are trying to fall pregnant, the timing of when you and your partner have sex is critical. Our online ovulation calculator can help you understand your fertile window or your window of opportunity to fall pregnant during a normal menstrual cycle. You should be having sex every couple of days during your fertile window.

For our Ovulation Calculator to be the most accurate and useful, you’ll need to keep track of the dates of your recent menstrual periods. 

Your cycle length is the number of days between the first day of bleeding of one period, and the first day of bleeding of the next. This can vary from 23 to 35 days, and 28 days is about average. If you have irregular menstrual cycles, calculating your ovulation date can be more difficult, but we suggest going by your shortest period date to ensure you don’t miss your ovulation date. Ovulation urine tests can give you some idea of your fertility window, or you might find further advice from your GP or fertility specialist useful.