Enter the first day of your last period and your average cycle length in days (21 to 40), then press Calculate. You will see your estimated ovulation date, fertile window and next period date.
Ovulation usually happens about 14 days before the next period starts. The calculator adds your cycle length to the first day of your last period and subtracts 14 days.
It is the days when the chance of conception is highest. The calculator shows the window from 5 days before ovulation to the day after it: sperm can survive for up to 5 days, while the egg lives about a day.
It is an estimate based on an average cycle. The real date can shift because of stress, illness, travel and other factors, especially with irregular cycles. Ovulation tests or tracking basal body temperature give a more precise picture.
No. Calendar-based estimates do not protect against pregnancy. Talk to a doctor about contraception or planning a pregnancy.
No. The calculation runs right in your browser and the dates you enter are never sent anywhere.