Estimate your baby’s due date from your last period, conception date, IVF transfer or an ultrasound, with conception and trimester dates.
About this tool
Estimate your baby's due date from your last period, conception or IVF transfer date.
How to use Due Date Calculator
- Choose what to calculate from: last period, conception, IVF transfer or ultrasound.
- Enter the date (and cycle length or scan age if asked).
- Read the due date and key pregnancy dates.
Worked example
With a last period starting 1 January and a 28-day cycle, the estimated due date is 8 October.
How is the due date calculated?
Naegele’s rule adds 280 days (40 weeks) to the first day of the last period, adjusted for cycle length.
How accurate is the due date?
Only about 4% of babies arrive on the day; most come within two weeks either side. An early ultrasound is the most accurate way to date a pregnancy.
- Due Date Calculator — Estimate your baby's due date from your last period, conception or IVF transfer date.
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