BMI Calculator
Body mass index from your weight and height, with the standard weight category.
BMI Calculator
| Body mass index (BMI) | 22.9 |
| Weight category | Normal weight (18.5–24.9) |
A person weighing 70 kg at 175 cm has a BMI of 22.9 — inside the normal weight range of 18.5–24.9.
Body mass index (BMI) is a screening measure that compares your weight with your height: BMI = weight (kg) ÷ height (m)². It was popularised by the World Health Organization as a quick way to classify adults as underweight, normal weight, overweight or obese.
BMI is an estimate for population screening, not a diagnosis — it does not distinguish muscle from fat, so athletes can score high while being lean. Treat the result as a starting point for a conversation with a clinician, not medical advice.
The formula
Worked example
A person weighing 70 kg at 175 cm has a BMI of 22.9 — inside the normal weight range of 18.5–24.9.
The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.
Frequently asked questions
What is a healthy BMI range?
For most adults, 18.5–24.9 is classified as normal weight, below 18.5 is underweight, 25–29.9 is overweight and 30 or above is obese. These cut-offs come from WHO guidance.
Why can BMI be misleading?
BMI ignores body composition and fat distribution. A muscular athlete may be classed overweight, and an older adult with low muscle mass may be classed normal despite high body fat. Waist circumference and body-fat percentage give a fuller picture.
Is BMI used for children?
Not directly — children and teens are assessed with age- and sex-specific BMI percentiles, because healthy body fat changes as they grow. This calculator uses the adult categories.
Category: Health & Fitness calculators
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