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Ovulation calculator
The likely fertile days and ovulation of your next three cycles, from your last period and cycle length. Free, with no account or uploads.
Your likely fertile days
Type the first day of your last period and your usual cycle length. It is an estimate, never birth control.
From the first day of one period to the first day of the next.
Type a date to see the answer.
This is arithmetic on your numbers, not medical advice; ask a doctor, nurse or midwife about your own health. Worked out in your browser; nothing you type is sent anywhere or kept, and this page has no adverts.
A little help along the way
Follow these steps. Every option is explained underneath. Everything runs in your browser; nothing is sent anywhere or kept.
- Say what you want to work outA due date, how far along you are, the conception date, or your fertile days.
- Say what you are counting fromYour last period, a due date you were given, conception, an IVF transfer or a scan.
- Type the dateWith your usual cycle length for a period, the embryo's age for IVF, or the age a scan gave.
- Read the answerIn words, with the rule it was counted by; add a due date to your calendar.
Questions people ask
- How are the fertile days worked out?
- Ovulation is taken as 14 days before the next period, and the fertile days as the six days ending on it (Wilcox and others, New England Journal of Medicine, 1995).
- Can I use this to avoid pregnancy?
- No. Cycles and ovulation vary from month to month, so a calendar estimate is not birth control.
- Is my cycle kept?
- No. Nothing you type is sent anywhere or kept, and the page has no adverts.
This page is the Pregnancy calculator, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the Pregnancy calculator's own page.
Read the step-by-step guide