Using the due date calculator

To find your due date, enter the date of the first day of your last period and click ‘Calculate my Due Date’ – the calculator will do the rest. Pregnancy normally lasts from 37 weeks to 42 weeks from the first day of your last period.

How does the pregnancy due date calculator work?

• Add 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28-day cycle).

• Your menstrual period and ovulation are counted as the first two weeks of pregnancy. This is why a pregnancy ovulation calculator can be helpful to pinpoint the exact ovulation cycle.

• If you deliver on your due date, your baby is actually only 38 weeks old, not 40.

How accurate is the due date calculator?

This date is just an estimate, only about 4% of babies are born on their due date. Although this tool can give you a roughly estimated date of when to expect your baby, we know all too well that baby.