Due Date Calculator
Estimate your pregnancy due date from your last period, conception, IVF, or ultrasound.
LMP + 280 days = estimated due date (Naegele's rule)
Enter a date to estimate your due date.
This is an estimate only and not medical advice. Due dates vary; a normal birth can occur between 37 and 42 weeks. Consult your doctor or midwife for an accurate assessment.
Frequently Asked Questions
How is my due date calculated?
The default method uses Naegele’s rule: 280 days (40 weeks) from the first day of your last menstrual period (LMP). You can also estimate from a conception date (266 days), an IVF transfer (261 days for a day-5 embryo, 263 for day-3), or an ultrasound, which projects the date from the gestational age measured at the scan.
How accurate is a due date?
A due date is an estimate, not a deadline. Only about 1 in 20 babies arrives on the exact date, and a normal birth can happen any time from 37 to 42 weeks. An early ultrasound is generally the most accurate way to date a pregnancy.
Is my last-period date stored anywhere?
When you use the LMP method, your date is saved only in your own browser (localStorage) so the Due Date, Ovulation, and Pregnancy Week calculators can pre-fill it. It is never sent to a server. Remove it any time with "Forget my data".