Due date calculator

Have you tried adding, subtracting, multiplying and counting on your fingers? Find out when your baby is due with our handy pregnancy calculator.

How is my pregnancy due date calculated?

Unless you've been tracking your ovulation, there's no way to know for sure exactly when you ovulated and conceived. That's why your due date is calculated based on the date of your last period instead.

Most people will ovulate about two weeks before the first day of their period, and conceive shortly afterwards. The average pregnancy lasts between 37 weeks and 42 weeks. Our calculator uses this information to give you an estimated due date.

Will my baby definitely be born on my due date?

Unfortunately, no one can say for sure exactly when your baby will arrive. In fact, only about four per cent of babies are born on their due date! But it's likely that your baby will arrive in the few weeks either side of your estimated due date. Knowing this can help you to be prepared for labour and birth, and to have everything ready for your new baby.

Will my due date change when I have a scan?

It may do. Your first pregnancy scan will probably happen when you're between 10 weeks and 14 weeks pregnant. It will either be a dating scan or the nuchal translucency (NT) scan, and gives you a more accurate due date, based on the size and development of your baby.

Learn more about antenatal scans.