🤰 Pregnancy Due Date Calculator
🔒 Sicher & Clientseitig
Enter the first day of your last menstrual period (LMP) and your typical cycle length. The calculator returns the estimated due date, your current pregnancy week and day, the trimester, and how many days remain until delivery. Naegele's rule plus a cycle-length adjustment.
Estimate only — not medical advice. Only ~5% of babies arrive on the predicted due date. An ultrasound dating scan is more accurate, especially if cycles are irregular.
How to use
- Pick the first day of your last menstrual period (LMP). This is day 1 of the cycle that resulted in pregnancy.
- Enter your typical cycle length. The default is 28 days; adjust if yours is consistently shorter or longer.
- Click Calculate. You'll see the estimated due date, your current pregnancy week, the trimester, and days remaining.
Formula (Naegele's rule): due date = LMP + 280 days, then adjusted by (cycle length − 28) days to account for variations in ovulation timing. Pregnancy is dated from LMP (not conception), so week 1 starts before you actually conceived. Trimesters: 1st (weeks 1–13), 2nd (14–27), 3rd (28–40+).
If your cycles are irregular or you don't know your LMP, an ultrasound dating scan in the first trimester is the most accurate method.