Estimate your due date, current pregnancy week and trimester from the first day of your last period. Free, private, no sign-up.
Based on Naegele's rule: LMP + 280 days (40 weeks). Only ~5% of babies arrive exactly on the due date — treat it as a guide.
Enter the first day of your last menstrual period (LMP). The tool applies Naegele's rule — LMP plus 280 days — to estimate the due date, then shows your current week, trimester and conception window.
Naegele's rule assumes a regular 28-day menstrual cycle and averages 40 weeks (280 days) of pregnancy. Only about 5% of babies are born exactly on their due date — most arrive within two weeks before or after. Cycle length, ovulation timing and ultrasound measurements can shift the estimate, so treat the result as a guide, not a promise.
This tool provides general information only and is not medical advice. Every pregnancy is unique — always follow the guidance of your doctor or midwife, who can date your pregnancy with ultrasound and clinical evaluation.
Everything runs entirely in your browser. Nothing you type is ever sent to any server or stored.
With Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. It is the standard clinical estimate.
Only about 5% of babies arrive exactly on the due date — most are born within two weeks of it. Treat it as a guide.
Conception typically happens around 14 days after the LMP, which the tool shows as a reference.
The tool counts full weeks since the LMP. Pregnancy is measured this way even before conception.
First trimester: weeks 1-13. Second: weeks 14-26. Third: weeks 27-40.
Yes, completely free, and the calculation happens on your device.
No — this is an educational estimate. Always confirm dates and care with a qualified healthcare provider.