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BMI Calculator

Calculate your Body Mass Index (BMI) instantly. Enter your weight and height to compare the result with adult BMI categories.

Units
lb
in
Examples

A 70 kg person who is 175 cm tall.

Your BMI
22.9 kg/m²
Category
Normal

You're in the healthy weight range — well done.

Screening tool only — not a medical diagnosis. BMI does not measure body fat directly and may misclassify athletes, older adults, pregnant people, and some ethnic groups. Talk to a healthcare provider before changing your diet, exercise, or treatment based on this result.

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Examples

How It Works

Formula

BMI=mh2\text{BMI} = \frac{m}{h^{2}}

Variables

BMI\text{BMI}

Body Mass Index(kg/m²)

mm

Body weight(kg)

hh

Height(m)

BMI is calculated by dividing your body weight in kilograms by the square of your height in metres. The resulting number is compared against adult BMI category ranges. While BMI is a useful screening tool, it does not directly measure body fat or account for factors like age, sex, ethnicity, or muscle mass.

Frequently Asked Questions

01What is a healthy BMI range?
CDC adult BMI categories classify 18.5 to less than 25 as healthy weight. Values below 18.5 are underweight, 25 to less than 30 are overweight, and 30 or higher is obesity.
02Is BMI accurate for athletes?
BMI does not distinguish between muscle mass and fat mass. Athletes with significant muscle may register as overweight or obese despite having low body fat. For a more complete picture, consider complementary measures like waist circumference or body fat percentage.
03Does BMI differ for men and women?
The standard adult BMI formula and category thresholds are the same for adult men and women. Sex, age, ethnicity, and muscle mass can affect how BMI relates to body fat, so context matters when interpreting the result.
04Can I use BMI for children?
Children and teenagers use age- and sex-specific BMI-for-age percentiles rather than the adult thresholds. A pediatrician can help interpret a child's BMI correctly with the appropriate growth chart.
05How often should I check my BMI?
For most adults, checking BMI once every few months is sufficient. If you are actively trying to gain or lose weight, monthly checks can help you track progress, but daily fluctuations in weight make more frequent checks unreliable.

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