How to use it
- Enter the first day of your last period.
- Change the cycle length if your cycle is usually shorter or longer than 28 days.
- Read the due date, your weeks today and the key dates.
Questions and answers
How is the due date calculated?
With Naegele’s rule: 280 days (40 weeks) after the first day of the last period, adjusted for cycles longer or shorter than 28 days.
How accurate is it?
It is an estimate. Only about 4% of babies are born on the due date, and most arrive within two weeks of it. An early ultrasound gives the most reliable dating.
Is my information saved?
No. The dates are calculated in your browser and nothing is sent or stored.