Tommy's PregnancyHub

Due date pregnancy calculator

Just found out you’re pregnant? Work out when your baby is due with our pregnancy due date calculator.

Calculate your due date

How to use the pregnancy calculator

To find your pregnancy due date you just need to select the date of the first day of your last period on our pregnancy calculator tool and click 'submit.'

You will then receive your estimated due date and the option to sign-up to our pregnancy email. This weekly email gives you fun pregnancy facts, useful tips and great recipe ideas to help you and your baby have the healthiest possible pregnancy.

Are you in early pregnancy? Find out all you need to know about week 4 onwards here.

How accurate is the due date?

The pregnancy calculator gives you an approximate due date, which it works out your due date by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle, it is adjusted for longer or shorter cycles). Your period and ovulation are counted as the first two weeks of pregnancy. If you have the baby on your due date, your baby has been growing for 38 weeks, not 40, but you are still classed as 40 weeks pregnant. 

Will I get a more accurate due date later in the pregnancy?

You will have your first appointment with the midwife, the 'booking appointment', between 8 weeks and 12 weeks pregnant. Here you will be given a scan and receive an accurate date for your baby's birth. But if you're impatient to know when your baby will arrive, then our pregnancy calculator tool gives you an estimate due date without the wait.

Review dates

Last reviewed: 1 April, 2014.
Next review: 1 April, 2017.