Rohrer Index Calculator

The Rohrer Index is a body mass index primarily used to evaluate the physique of school-age children (elementary to junior high school). It is calculated using the formula: weight(kg) ÷ height(cm)³ × 10⁷. The Rohrer Index is widely adopted in Japanese school health programs and is used as a standard metric in regular school health examinations.

Unlike BMI, which divides by the square of height, the Rohrer Index divides by the cube of height. This makes it more accurate for children whose height varies significantly during growth periods. BMI was originally designed for adults and can be unreliable for growing children. The Rohrer Index, by contrast, is specifically designed to accommodate the body composition changes characteristic of the growth stage.

The classification guidelines are as follows: below 100 is severely underweight, 100–115 is underweight, 115–145 is normal, 145–160 is slightly overweight, and 160 or above is overweight. This tool calculates and displays results in real-time, visualizing the 5-level classification with color-coding. Additionally, BMI values are calculated simultaneously and displayed as reference values, enabling more comprehensive body composition assessment.

Note that neither index distinguishes between muscle and fat, so children with well-developed muscles from exercise may show higher values. It is advisable to consult with healthcare professionals when interpreting the results.