Bone Age and Chronological Age Calculator
Updated October 12, 2026
What is the difference between bone age and chronological age?
Bone age is an estimate of skeletal maturity on a radiograph, and chronological age is the calendar time from the birthday to the X-ray date. Bone Ager predicts bone age from the left-hand image and the selected sex. The birthday and the X-ray date display chronological age and look up the Brush mean. The image model does not receive chronological age, height, or weight.
How the Page Uses Each Age
Enter the birthday and the X-ray date as 9/19/95, September 19, 1995, or 091995. The page counts completed months between those dates and shows that chronological age in years and months, plus the total in months. The X-ray date defaults to today. For an older film, enter the acquisition date.
The Greulich and Pyle display looks up the Brush mean and standard deviation for that chronological age and sex. A bone age above or below the two-standard-deviation band around the Brush mean is labeled Advanced or Delayed. The method is described on Greulich and Pyle Bone Age Calculator. The measured model error is on About.
Sex is the only patient detail the image model receives. Select female or male before the estimate. Tanner stage, height, weight, and trunk height stay out of the network.