CalcMate

BMI Calculator

Calculate your Body Mass Index from height and weight in metric or imperial units, see your WHO weight category, and the healthy weight range for your height.

How to use the BMI calculator

Choose metric or imperial units, enter your height and weight, and your Body Mass Index appears instantly along with your weight category and the healthy weight range for your height. Nothing is sent to a server — the calculation happens entirely in your browser.

What BMI actually measures

Body Mass Index is a ratio of weight to height that estimates whether you are carrying a healthy amount of weight for your size. It was designed for population-level screening, which is why it works well as a fast first check but should not be read as a precise measure of body fat. A single BMI number is most useful when tracked over time or read together with measurements like waist circumference and body composition.

Reading your result

A BMI in the 18.5–24.9 band is classified as a normal, healthy weight. Below that is underweight, 25–29.9 is overweight, and 30 or above is obese. Small movements within a band rarely matter; crossing a band boundary is a better prompt to review your habits or speak to a healthcare professional. The healthy weight range this tool shows is the span of weights that would keep you inside the normal band at your current height.

Frequently Asked Questions

How is BMI calculated?

BMI is your weight in kilograms divided by the square of your height in metres: BMI = kg ÷ m². For imperial units the formula is (pounds ÷ inches²) × 703. A person 1.70 m tall weighing 65 kg has a BMI of 65 ÷ (1.70 × 1.70) = 22.5.

What is a healthy BMI range?

The World Health Organization defines a BMI below 18.5 as underweight, 18.5 to 24.9 as normal weight, 25 to 29.9 as overweight, and 30 or above as obese. These bands apply to most adults aged 20 and over regardless of sex.

Is BMI accurate for everyone?

BMI is a quick screening tool, not a diagnosis. Because it only uses height and weight, it can overestimate body fat in very muscular people and underestimate it in older adults who have lost muscle. It is also not designed for children, pregnant people, or athletes. Treat it as a starting point and discuss concerns with a healthcare professional.

What is the healthy weight range shown by this calculator?

It is the weight range that would put your BMI between 18.5 and 24.9 at your current height. It is calculated by rearranging the BMI formula: weight = BMI × height². This gives you a concrete target range instead of a single number.

Does BMI differ for men and women?

The BMI formula and the standard WHO categories are the same for adult men and women. However, at the same BMI women tend to have more body fat than men, which is one reason BMI is best used alongside other measures such as waist circumference.

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