Fetal Biometry Percentile Calculator
Enter the gestational age and a fetal biometric measurement to estimate its percentile in the normal population, helping judge whether it deviates from the normal growth range. Supports common parameters such as biparietal diameter, head circumference, abdominal circumference, femur length and transverse cerebellar diameter.
① Choose a parameter and enter values
How to use & methodology
How is the percentile interpreted?
The percentile shows where the measurement sits in the normal population. For example, the 50th percentile is the median; below the 3rd or above the 97th percentile is usually a critical value suggesting deviation from normal and warranting further attention — but a single measurement cannot diagnose directly.
Can this tool be used for clinical diagnosis?
Not on its own. It uses an approximate model based on public literature for quick research and teaching estimation. Clinical interpretation must combine your institution's local reference standards, serial follow-up, other biometric parameters and the physician's overall judgment.
Which parameters are supported?
Currently biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and transverse cerebellar diameter (TCD), for gestational ages roughly 14–40 weeks. Select a parameter, enter the gestational age and measured value to get the percentile and the reference values at that gestational age.
Why might the result differ slightly from my hospital's standard?
Different reference standards (Hadlock, INTERGROWTH-21st, WHO, local standards) are based on different populations, so normal values differ. This tool is for trend/estimation reference; if it disagrees with your hospital's routine standard, follow your hospital's standard.