Pregnancy week calculator by due date

The calculator on this page can help you work out when you might expect your baby to arrive. This is known as your estimated due date (EDD).

Using the due date calculator

To find your estimated due date (EDD), enter the date of the first day of your last period, and select 'show your estimated due date'.

Pregnancy normally lasts from 37 weeks to 42 weeks from the first day of your last period.

You need to know the first day of your last period to use this calculator. If you do not know it or are unsure, speak to a midwife or GP.

As part of your pregnancy (antenatal) care, your midwife will offer you a 12-week scan.

This scan can more accurately estimate how many weeks pregnant you are.

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Unplanned or unsure?

Find out about making a decision about a pregnancy (Brook website).