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Free BMI Calculator Online

Calculate your Body Mass Index instantly. Enter height & weight in metric (cm/kg) or imperial (ft/lbs) and see your BMI, category, and healthy weight range.

Instant Results
Metric & Imperial
Completely Free

BMI Categories (WHO Standard)

BMI Range Category Health Risk
< 18.5UnderweightMalnutrition risk
18.5 – 24.9Normal weightLow risk
25 – 29.9OverweightModerate risk
30 – 34.9Obese Class IHigh risk
≥ 35Obese Class IIVery high risk
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Frequently Asked Questions

BMI (Body Mass Index) is a number calculated from your height and weight. It is used as a screening tool to indicate whether you are underweight, normal weight, overweight, or obese. Formula: BMI = weight(kg) / height(m)².
According to WHO: Under 18.5 = Underweight, 18.5–24.9 = Normal weight, 25–29.9 = Overweight, 30–34.9 = Obese Class I, 35+ = Obese Class II. A BMI between 18.5 and 24.9 is considered healthy for most adults.
Yes. Switch to Imperial mode and enter your height in feet & inches and weight in pounds. The calculator converts them automatically and applies the correct formula.
Metric: BMI = weight (kg) / (height in metres)². Imperial: BMI = 703 × weight (lbs) / (height in inches)². For example, 70 kg at 175 cm = 70 / (1.75)² = 22.86 — Normal weight.
BMI is a useful screening tool but has limitations. It does not account for muscle mass, bone density, age, or gender differences. Athletes may have a high BMI due to muscle, not fat. Always consult a doctor for a complete health assessment.
CodBolt's BMI calculator shows your healthy weight range automatically — the weight range that corresponds to a BMI of 18.5–24.9 for your entered height.