​Working out your due date

Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming you have a 28 day cycle).

You can use the NHS pregnancy due dat​e calculator to help you work out when you might expect your baby to arrive.

Dating scan

The NHS pregnancy calculator should only be used as a rough guide. As part of your antenatal care, you'll be offered a dating scan (12 week scan) that will give you a more accurate date for the birth of your baby.