Due Date Calculator
Enter the first day of your last menstrual period or your conception date, and this calculator estimates your due date, current week of pregnancy, and trimester using standard obstetric rules of thumb.
How it works
Choose whether you're entering the first day of your last menstrual period (LMP) or your conception date. From the LMP, the due date is estimated as 280 days later (Naegele's rule); from a conception date, it's estimated as 266 days later. Your current week and trimester are calculated from there.
Tip
Due dates are easiest to estimate from the first day of your last period if you have a regular cycle length around 28 days; if your cycle is longer or shorter, or you know your conception date more precisely, use the conception date mode instead.
How accurate is this estimate?
This due date is only an estimate based on a standard rule of thumb (Naegele's rule) — every pregnancy is different, and actual delivery dates commonly fall anywhere from two weeks before to two weeks after the calculated date. This is not medical advice; talk to your doctor or midwife, and rely on an ultrasound-based estimate for a more precise date.
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