Calculate your estimated due date based on your last menstrual period or conception date.
The most common method uses Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This calculator also adjusts for irregular cycle lengths and supports calculation from conception or IVF transfer dates.
The due date is an estimate. About 80% of babies are born within 2 weeks of their due date, but only 5% arrive exactly on the predicted date.