Free tool

Conception date
calculator

Enter your due date, your last period or your ultrasound details to estimate when conception happened.

Enter a date to see your result here.

How is it calculated?

Pregnancy is counted from the first day of the last period, assuming a 28-day cycle with ovulation about two weeks later. So the estimated conception date is 266 days (38 weeks) before the due date. If you enter your last period or an ultrasound, the due date is calculated first.1

This is an estimate. The date set by your doctor is the one to go by.

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