Due date calculator

Enter the first day of your last period. We count 280 days (40 weeks) from that date, the standard method doctors use for a first estimate.

How the due date is calculated

The estimate adds 280 days to the first day of your last menstrual period, adjusted if your cycle is longer or shorter than 28 days. Only a small share of babies arrive exactly on their due date; most are born within about two weeks of it. An early ultrasound can give a more accurate date, so your provider may update the estimate after your first scan.

This calculator gives an estimate only and does not replace advice from your doctor or midwife.