Age
ages: 2 - 120
Gender
Height
Weight
Result
Enter your details and click Calculate to see your BMI result.
User Guide
How to Use
- Select your unit system: US (feet+inches / lbs), Metric (cm / kg), or Other (feet+inches / stone+lbs).
- Enter your age, gender, height, and weight.
- Click Calculate to get your BMI and related metrics.
- The gauge shows your BMI category visually.
BMI Formula
- US Units: BMI = 703 × weight(lbs) ÷ height(in)²
- Metric Units: BMI = weight(kg) ÷ height(m)²
BMI Categories (Adults age 20+)
< 18.5 Underweight
18.5 – 24.9 Normal
25 – 29.9 Overweight
30 – 34.9 Obese Class I
35 – 39.9 Obese Class II
≥ 40 Obese Class III
The Underweight zone is subdivided on the gauge: <16 (Severe), 16–17 (Moderate), 17–18.5 (Mild). For children and teens (ages 2–19), categories are based on CDC age- and sex-specific percentile charts.
FAQ
Q: What is a healthy BMI?
A: A BMI between 18.5 and 24.9 is considered healthy for most adults.
Q: Is BMI the same for men and women?
A: The BMI formula is identical, but body composition differences mean health implications can vary.
Q: Does BMI apply to children?
A: BMI for children (ages 2–19) uses age- and sex-specific percentiles and is interpreted differently.
Q: What is BMI Prime?
A: BMI Prime is your BMI divided by 25. A value of 1.0 means you are exactly at the upper boundary of normal weight.
Q: Is this calculator free?
A: Yes, 100% free with no limits.
About This BMI Calculator
Body Mass Index (BMI) is a screening measure of body fat based on height and weight for adult men and women.
This free online BMI calculator supports US units (feet, pounds), metric units (centimetres, kilograms), and mixed units. Results include BMI category, healthy weight range, BMI Prime, and Ponderal Index.
BMI Categories (WHO classification):
- Severe Thinness: BMI < 16
- Moderate Thinness: BMI 16–16.9
- Mild Thinness: BMI 17–18.4
- Normal: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Obese Class I: BMI 30–34.9
- Obese Class II: BMI 35–39.9
- Obese Class III: BMI ≥ 40