Free tool
Pregnancy due date calculator
Enter the first day of your last period. We'll estimate your due date, current week and trimester.
Frequently asked questions
How is the due date calculated?
The common method (Naegele's rule) adds 280 days — 40 weeks — to the first day of your last menstrual period. Your doctor may adjust it after an ultrasound.
How accurate is a due date?
It is an estimate. Only a small share of babies arrive on the exact date; most come within two weeks either side.
An estimate only — not medical advice. Your doctor will confirm your due date.