When is your
baby due?
Estimate your due date from the first day of your last period.
A starting point for planning your pregnancy care.
Let’s work out your dates.
Your dates are calculated on this device. They are not saved or sent to the hospital.
Start with your last period.
Your estimated due date, pregnancy week and progress will appear here.
An estimate.
Confirmed with your doctor.
A due date is a planning estimate, not a prediction of the day your baby will be born. Your doctor may revise it after reviewing your dates and ultrasound. If your maternity team has already given you a date, use that.
Meet Dr. Nitin YadavHow is the date calculated?+
For a 28-day cycle, we add 280 days (40 weeks) to the first day of your last period. We adjust this by the difference between your usual cycle length and 28 days. Estimated pregnancy weeks are adjusted by the same amount.
What if my periods are irregular?+
This calculation is less reliable if your cycles vary, you do not know your last-period date, or your pregnancy followed IVF. Ask your maternity team to establish the date from your clinical history and scan.
Does this confirm a pregnancy?+
No. This calculator works with the dates you enter. It cannot confirm pregnancy or assess your health.
Where does this method come from?+
The method follows the standard last-period calculation described by ACOG and the cycle adjustment used by the NHS due-date calculator. The dates are an estimate; ultrasound may provide more accurate dating.