Pregnancy due date calculator

Estimate your due date and current pregnancy week from the first day of your last menstrual period (LMP), using the standard 40-week timeline.

Last menstrual period

First day of LMP

Average cycle length (days) Default 28 days; adjustment shifts estimated ovulation

Results

Enter LMP date to estimate.

How this works

Naegele’s rule estimates due date as LMP + 280 days (40 weeks), with a small adjustment when cycle length differs from 28 days. Ultrasound dating from your clinician is more accurate.

Medical disclaimer: This tool is informational only and is not a substitute for professional prenatal care. Always confirm dates with your doctor or midwife.