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Due Date Calculator

Calculate your estimated due date from your last menstrual period using Naegele's rule. Adjusts for cycle length and shows gestational age, estimated ovulation date, and days remaining.

This tool gives an estimate based on a common formula (Naegele's rule). Always consult an obstetrician for any decisions about your pregnancy or delivery timing.

Input

YYYY/MM/DD
days

Result

Please enter the first day of your last menstrual period.

How it works

  • The due date is calculated with Naegele's rule, treating the first day of your last menstrual period as 0 weeks 0 days and adding 280 days (40 weeks 0 days).
  • If your menstrual cycle is longer or shorter than 28 days, the difference is added to or subtracted from the due date (a longer cycle shifts the due date later).
  • It also shows an estimate of the gestational period, the ovulation date (about 14 days after the first day of your last period), and the days remaining until the due date.
  • Actual gestational age and delivery date may be corrected by ultrasound, and relatively few people give birth exactly on the estimated date.
  • This tool is a general estimate based on Naegele's rule and is not a diagnosis or medical advice. Always consult a doctor for decisions about pregnancy and childbirth.