BMI (Body Mass Index) is a number calculated from your weight and height. It provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively.

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is generally considered normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese according to the WHO.

How is BMI calculated?

In metric units: BMI = weight (kg) ÷ height² (m²). In imperial units: BMI = (weight (lbs) ÷ height² (in²)) × 703.

Is BMI accurate for everyone?

BMI has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI without excess body fat. It also doesn't account for age, sex, ethnicity, or body fat distribution. It's best used as a starting point, not a definitive health measure.

Does BMI apply to children?

For children and teens aged 2–20, BMI is calculated the same way but interpreted using age- and sex-specific percentile charts. This calculator is designed for adults.

Calculators

BMI Calculator

Calculate your Body Mass Index (BMI) using either metric or imperial measurements. BMI is a simple screening tool that uses height and weight to estimate whether a person is underweight, normal weight, overweight, or obese.

Your Measurements

Weight (kg)

Height (cm)

Your BMI

22.9Normal weight

Under 18.5
Underweight

18.5–24.9
Normal

25–29.9
Overweight

30+
Obese

Disclaimer: BMI is a general screening tool and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a healthcare provider for a comprehensive health assessment.

Usage notes

BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, or body composition.
For athletes or very muscular individuals, BMI may overestimate body fat.
Consult a healthcare professional for a complete health assessment.

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How to Use This Tool

1Select your preferred measurement system: Metric (kg/cm) or Imperial (lbs/ft-in).
2Enter your weight and height in the corresponding fields.
3Your BMI value and weight category appear instantly below.

Frequently Asked Questions

What is BMI?: BMI (Body Mass Index) is a number calculated from your weight and height. It provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively.
What is a healthy BMI range?: A BMI between 18.5 and 24.9 is generally considered normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese according to the WHO.
How is BMI calculated?: In metric units: BMI = weight (kg) ÷ height² (m²). In imperial units: BMI = (weight (lbs) ÷ height² (in²)) × 703.
Is BMI accurate for everyone?: BMI has limitations. It doesn't distinguish between muscle and fat, so athletes may have a high BMI without excess body fat. It also doesn't account for age, sex, ethnicity, or body fat distribution. It's best used as a starting point, not a definitive health measure.
Does BMI apply to children?: For children and teens aged 2–20, BMI is calculated the same way but interpreted using age- and sex-specific percentile charts. This calculator is designed for adults.