BMI Calculator
Calculate your Body Mass Index and find your healthy weight range.
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BMI Calculator
Use the formula and worked example below to calculate manually.
Overview
The BMI (Body Mass Index) calculator estimates your body weight status — underweight, normal, overweight, or obese — based on your height and weight. It's a widely used screening tool for potential health risks.
How to use this calculator
- Select your unit system (metric or imperial).
- Enter your height (cm or ft/in).
- Enter your weight (kg or lbs).
- The calculator shows your BMI value, category, and healthy weight range for your height.
Understanding the inputs & results
BMI
Body Mass Index — a ratio of weight to height squared. Used to classify weight status.
Underweight
BMI below 18.5. May indicate malnutrition or an underlying health condition.
Normal weight
BMI 18.5–24.9. Associated with lower risk of weight-related health issues.
Overweight
BMI 25–29.9. Increased risk of heart disease, diabetes, and hypertension.
Obese
BMI 30 or above. Significantly increased risk of chronic health conditions.
Healthy weight range
The weight range corresponding to a BMI of 18.5–24.9 for your height.
The formula
BMI formula
BMI = Weight (kg) / Height² (m²)
Divide your weight in kilograms by the square of your height in metres. For imperial: BMI = 703 × weight (lbs) / height² (inches²).
Worked example
Weight 70 kg, Height 1.75 m.
- BMI = 70 / (1.75)² = 70 / 3.0625 ≈ 22.86.
- Category: Normal weight (18.5–24.9).
✓ BMI = 22.86 — Normal weight.
Frequently asked questions
BMI is a general screening tool and not a substitute for medical examination. Consult a doctor before making any health decisions based on your BMI.