Gestational Age and Estimated Due Date (EDD) Calculator

Accurate prenatal care based on the Date of Last Menstrual Period (LMP).

Nurses, encourage pregnant women to attend prenatal care appointments, which are essential for reducing maternal and infant mortality. Prenatal care provides guidance on nutrition, care, family planning, and vaccinations, and promotes maternal empowerment. The estimated due date (EDD) should be calculated based on ultrasound results and the date of the last menstrual period, assuming a 40-week pregnancy.

GI and EDD Calculator

How to Perform the Calculations:

1. Estimated Date of Delivery (Naegele’s Rule)

Add 7 days to the first day of the LMP. Adjust the month:

  • Jan–Mar: Add 9 months.
  • Apr–Dec: Subtract 3 months.
Ex: LMP on Feb. 10:
10 + 7 = 17 (day) | Feb. + 9 months = Nov. EDD: Nov. 17
2. Gestational Age (in weeks)

Count the exact number of days from the LMP to today. Divide by 7. The whole number is the week; the remainder is the number of days.

Ex: 69 days elapsed:
69 ÷ 7 = 9 (remainder 6). GA: 9 weeks and 6 days.