how to calculate menstrual cycle and ovulation?

Ovulation calculator
Estimate your fertility window with our easy-to-use ovulation calculator

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

IVFAustralia's Ovulation Calculator will help you understand your ‘fertile window’ – or your window of opportunity to fall pregnant during an average menstrual cycle. You should be having sex every couple of days during your fertile window to maximise your chance of getting pregnant.

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. A woman's menstrual cycle can vary from 23 to 35 days, with the average cycle length being about 28 days. 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.
How to use our ovulation calculator

Simply select your usual cycle length from the dropdown box and then choose the date on the calendar when your last period started. With this information, our ovulation calculator estimates your next fertility window (and the next one after that).

Based on your results from our ovulation calculator, you can also sign up for handy email reminders, so you’ll always know your ‘Fertile Window' each month.