Due Date Calculator

Enter one date to see when your baby is due, how many weeks pregnant you are and which trimester you are in.

Last period Conception IVF Ultrasound Known due date

First day of your last period Conception date Embryo transfer date Ultrasound date Due date

Average cycle length (days)

Embryo age at transfer

Gestational age at the scan

How is the due date calculated?

A pregnancy lasts about 40 weeks (280 days), counted from the first day of the last period; conception usually happens about two weeks later. For cycles longer or shorter than 28 days, the date shifts by the difference. From a conception date we add 266 days; for IVF, 261 days (day 5 embryo) or 263 days (day 3 embryo). An early ultrasound is the most accurate, so if your doctor has set the due date from a scan, use that date.

The calculator gives an estimate only and is not medical advice. Your doctor or midwife will confirm the due date.