How is BMI calculated?

BMI = weight in kilograms divided by height in meters squared (kg/m²). In imperial units: BMI = 703 × weight in pounds / (height in inches)².

What is a normal BMI?

The WHO defines a BMI of 18.5–24.9 as the normal range for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is classified as obese.

Is BMI accurate for everyone?

No. BMI doesn't account for muscle mass, bone density, age, or body composition — athletes often have a high BMI with low body fat, and it isn't designed for children or pregnant women. Treat it as a rough screening number only.

BMI Calculator

Calculate your Body Mass Index (BMI) from your height and weight, in metric (cm, kg) or imperial (ft/in, lb) units. The result is placed on the World Health Organization scale — underweight, normal, overweight, or obese — and the tool also shows the weight range that corresponds to a normal BMI for your height. BMI is a screening indicator, not a diagnosis: it doesn't distinguish muscle from fat, so consult a healthcare professional for a full assessment.

Calculators

Metric (cm, kg)Imperial (ft, lb)

Height (cm)

Weight (kg)

Your BMI: 22.9
Category: Normal weight; WHO classification for adults
Healthy weight for your height: 56.7 kg – 76.3 kg; BMI 18.5 – 24.9

BMI is a screening measure and does not account for muscle mass, age, or body composition. It is not medical advice.

Private by default

This tool runs entirely in your browser. Your data is never uploaded to a server.

How to use

3 clear steps.

Choose metric or imperial units.
Enter your height and weight.
Read your BMI, its WHO category, and the healthy weight range for your height.

Good to know

Frequently asked questions

How is BMI calculated?: BMI = weight in kilograms divided by height in meters squared (kg/m²). In imperial units: BMI = 703 × weight in pounds / (height in inches)².
What is a normal BMI?: The WHO defines a BMI of 18.5–24.9 as the normal range for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is classified as obese.
Is BMI accurate for everyone?: No. BMI doesn't account for muscle mass, bone density, age, or body composition — athletes often have a high BMI with low body fat, and it isn't designed for children or pregnant women. Treat it as a rough screening number only.