Gestational Age Calculator

Calculate pregnancy weeks, days, and estimated due date with medical accuracy

LMP Based Medical Accuracy Export Reports

Calculate Gestational Age

First day of your last menstrual period
If known, enter estimated conception date
Leave blank to use today's date

Pregnancy Progress Chart

Pregnancy Milestones

Week Milestone Date Days from LMP

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About Gestational Age

Gestational age is the common term used during pregnancy to describe how far along the pregnancy is. It is measured in weeks and days from the first day of your last menstrual period (LMP).

Calculation Methodology

Naegele's Rule Formula: 
EDD = LMP + 280 days
  = LMP + 40 weeks
Where LMP is the first day of last menstrual period

For conception date calculations:

Conception-Based Formula: 
Gestational Age = (Current Date - Conception Date) + 14 days
EDD = Conception Date + 266 days

Pregnancy Trimesters

  • Baby's major organs begin to form
  • Heart starts beating around week 6
  • Morning sickness is common
  • First ultrasound typically around week 8-12

  • Baby's movements become noticeable
  • Anatomy scan around week 20
  • Gender can often be determined
  • Energy levels typically increase

  • Baby gains weight rapidly
  • Fetal movement monitoring important
  • Preparation for labor and delivery
  • Weekly checkups in late pregnancy

Frequently Asked Questions

Gestational age is the duration of pregnancy measured from the first day of the last menstrual period (LMP). It's the standard method used by healthcare providers to track pregnancy progress and estimate due dates.

This calculator uses standard medical formulas (Naegele's Rule) and provides estimates based on average pregnancy duration. Actual due dates may vary based on individual factors, menstrual cycle regularity, and ultrasound measurements.

Gestational age is measured from LMP, while fetal age (also called conceptual age) is measured from conception. Fetal age is approximately 2 weeks less than gestational age, as conception typically occurs about 2 weeks after LMP.

You need either your last menstrual period date OR conception date. The current date is optional (defaults to today). The calculator will use LMP if both dates are provided, as it's the standard medical reference.

This calculator provides estimates only. It doesn't account for irregular cycles, IVF pregnancies, or medical conditions. Ultrasound measurements by healthcare providers provide more accurate dating, especially in early pregnancy.