BMI Calculator

Body Mass Index (BMI) is a quick screening measure that uses your height and weight to estimate whether your weight falls in a healthy range. It takes seconds to calculate and is widely used by doctors and fitness professionals as a starting point for a fuller health assessment.

Fill in the form and select Calculate to see your result here.

What is BMI?

BMI is a simple ratio of your weight to your height, expressed as weight in kilograms divided by height in metres squared. It was designed as a population-level screening tool, not a diagnostic measurement for any one individual, but it remains a useful first indicator of whether your weight is in a range associated with lower health risk.

BMI Formula

BMI is calculated by dividing your weight in kilograms by the square of your height in metres. Because it only uses two inputs, it is fast to calculate but does not distinguish between muscle mass, fat mass, or body frame — two people with the same BMI can have very different body compositions.

BMI = weight (kg) ÷ height (m)²

BMI Example

A person who is 170 cm (1.70 m) tall and weighs 70 kg has a BMI of 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2, which falls in the "Normal weight" category.

BMI Categories (WHO Standard)

BMI Range	Category
Below 18.5	Underweight
18.5 - 24.9	Normal weight
25.0 - 29.9	Overweight
30.0 and above	Obese

How to Use This Calculator

Enter your height in centimetres.
Enter your current weight in kilograms.
Select "Calculate" to see your BMI value and category.
Use the related calculators below to explore your calorie needs and ideal weight range.

Limitations

BMI does not distinguish between muscle and fat, so muscular or highly athletic individuals can show a higher BMI without excess body fat.
It does not account for where fat is distributed on the body, age, sex differences in body composition, or bone structure.
BMI is a screening tool only — it is not a diagnosis and should not replace advice from a qualified healthcare professional.

Frequently Asked Questions

BMI is a useful general screening tool but is less accurate for athletes with high muscle mass, older adults, and pregnant women. Consider it one data point alongside body fat percentage and how you feel and perform.

For most adults, a BMI between 18.5 and 24.9 is considered to be in the normal weight range, though healthy ranges can vary by individual, ethnicity and body composition.

This calculator is designed for adults. Children and teenagers need age- and sex-specific BMI percentile charts, which a pediatrician can provide.

There is no need to check it more than monthly — weight naturally fluctuates day to day, and BMI is best used as a slow-moving trend indicator, not a daily metric.