Ovulation and period calculator
See when your next periods are due and which days you are most likely to conceive.
Ovulation and period calculator
How to use it
- Enter the date your last period started.
- Enter your usual cycle length, counted from day one of one period to day one of the next.
- Read your next three period dates and fertile windows.
Your entries stay in your browser. Nothing is sent to us. The result is for information and is not a diagnosis.
How ovulation is estimated
Ovulation usually happens about 14 days before the next period. The fertile window is the five days before ovulation and the day after, because sperm can survive for several days.
When cycles are irregular
If your cycle varies by more than a week, the dates will be unreliable. Irregular cycles are common with PCOS, thyroid problems, stress and weight change, and are worth discussing with a doctor.
Important
This calculator is not a method of contraception. If you have been trying to conceive for a year without success, or six months if you are over 35, see a gynaecologist. Both partners should be tested.
Questions
When is my next period?
Add your cycle length to the first day of your last period. The calculator shows the next three.
How many days after a period does ovulation happen?
In a 28-day cycle, around day 14 counted from the first day of the period.
Can I get pregnant outside the fertile window?
It is unlikely but possible, because ovulation can shift.
Prepared by the team at Babar Homeopathic Clinic & EyeBar Optical, Kangan Pur. Last updated 3 October 2026. See our medical disclaimer.
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