Pregnancy Due Date Calculator
Estimate your due date from the first day of your last menstrual period (LMP). We use Naegele's rule, adjusted for your average cycle length.
Most cycles fall between 21 and 35 days. Default is 28.
How it works
Naegele's rule adds 280 days (40 weeks) to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, we shift the estimate by the difference, since ovulation typically happens about 14 days before your next period.
This is an estimate only. Just 4–5% of babies arrive exactly on their due date — most arrive within two weeks on either side. For medical guidance, please consult your healthcare provider.