Gestational age calculator for preterm infants

Enter any available dates, ages, or gestations, and other values will be calculated.

Today is Wednesday, June 26th, 2019

Gestational Age Calculator

Last menstrual period
Due date

Date of birth
Gestational age at birth

Date of Interest
Age in days on Date
Day of life on Date
Postmenstrual age

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Instructions and notes:

  • Enter any known values. All possible other values will be calculated. Values that can not be calculated will be left blank.
  • Dates are interpreted semi-intelligently, but be aware of possible errors if unrecognized formats are used.
  • The due date is 40 weeks after the last menstrual period, or 38 weeks after conception (implantation / fertilization).
  • On the date of birth, a baby is on the first day of life (day of life 1), but is zero days old.
  • The first exam for retinopathy of prematurity is at 31 weeks postmenstrual age, but not before 4 weeks of age (typically indicated if born at <31 weeks gestation or birth weight <1,500 grams).