Ultrasound Gestational Age Calculator

Ultrasound Gestation Period Calculator

This calculator estimates the gestational age of a pregnancy based on ultrasound measurements, such as Crown-Rump Length (CRL) or Biparietal Diameter (BPD). Ultrasound-based dating is especially accurate in early pregnancy and helps track fetal development, estimate due dates, and schedule prenatal care.

Gestational Age Estimator by Ultrasound Data

Ultrasound Measurement to Gestational Age Formula

Formula

$$\text{Gestational Age (days)} = 42 + \left( \frac{\text{CRL (mm)}}{0.99} \right)$$

Ultrasound measurements like:

$$CRL$$ (Crown-Rump Length) — early pregnancy (6–13 weeks)
$$BPD$$ (Biparietal Diameter) — second trimester

can be mapped to standard growth charts to estimate gestational age.

Ultrasound is one of the most accurate methods for determining gestational age, especially in the first trimester. The measurement of the embryo or fetus—such as Crown-Rump Length (CRL), Biparietal Diameter (BPD), or Femur Length (FL)—can help doctors assess fetal development and calculate how far along the pregnancy is. This calculator helps convert ultrasound values into weeks and days of pregnancy. Knowing the gestational age is crucial for planning delivery, monitoring fetal health, and setting maternity leave timelines.