BMI Calculator

Estimate Body Mass Index From Height and Weight.It Supports Both Metric Units and Us Units, and It Also Shows BMI Prime,Ponderal Index, and Healthy Weight Ranges for Your Height.

How to Use the BMI Calculator

Choose either Metric Units or US Units, then enter your height and weight and click Calculate. The calculator will compute your Body Mass Index (BMI), show your BMI category, estimate the healthy weight range for your height, and display related measures such as BMI Prime and Ponderal Index.

BMI Formula

Body Mass Index (BMI) is calculated as:

Metric units:
BMI = weight (kg) / [height (m)]²

US units:
BMI = 703 × weight (lb) / [height (in)]²

BMI Prime Formula

BMI Prime is a simple ratio that compares your BMI to the upper limit of the normal BMI range:

BMI Prime = BMI / 25

A BMI Prime of 1.0 means the BMI is exactly 25.

Ponderal Index Formula

The Ponderal Index measures body mass relative to height cubed:

Ponderal Index = weight (kg) / [height (m)]³

This index can be useful when comparing people with different body proportions.

Example 1: Metric Units

Example (Metric):
Height = 185 cm = 1.85 m
Weight = 65 kg

BMI = 65 / (1.85 × 1.85) = 18.99

BMI Prime = 18.99 / 25 = 0.76

Ponderal Index = 65 / (1.85 × 1.85 × 1.85) = 10.26 kg/m³

Example 2: US Units

Example (US):
Height = 5 ft 10 in = 70 in
Weight = 150 lb

BMI = 703 × 150 / (70 × 70) = 21.5

BMI Prime = 21.5 / 25 = 0.86

Ponderal Index = 68.0 kg / (1.778 m × 1.778 m × 1.778 m) ≈ 12.1 kg/m³

References

• CDC – About Adult BMI: https://www.cdc.gov/bmi/adult-calculator/index.html
• NIH / NHLBI – Assessing Your Weight and Health Risk: https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm
• CDC – Healthy Weight, Nutrition, and Physical Activity: https://www.cdc.gov/healthyweight/index.html