BMI Calculator

Calculate your Body Mass Index from height and weight

Height (cm)

100cm170cm250cm

Weight (kg)

20kg70kg200kg

24.2

Normal

1018.5253040

UnderweightNormalOverweightObese

BMI Formula

BMI = Weight (kg) / Height (m)²

BMI (Body Mass Index) is a measure of body fat based on height and weight. It applies to adult men and women. A BMI of 18.5-24.9 is considered normal weight.

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What is BMI?

BMI (Body Mass Index) is an internationally recognized measure that relates your weight to your height to estimate whether you are in a healthy weight range. Using the categories defined by the World Health Organization (WHO), it classifies you as underweight, normal weight, overweight, or obese. Because it requires only a scale and a tape measure, BMI is widely used by doctors, gyms, and insurers as a quick, low-cost starting point for assessing weight-related health risk in adults.

How to use this calculator

1. Enter your height (in centimeters or feet/inches). 2. Enter your weight (in kilograms or pounds). 3. Press calculate to see your BMI value and health category on a visual gauge. Results update as you change the inputs, so you can also use it to explore a target weight.

Formula and definition

BMI is calculated as: BMI = weight (kg) ÷ height (m) ÷ height (m) For example, someone 1.75 m tall weighing 70 kg has a BMI of 70 ÷ 1.75 ÷ 1.75 ≈ 22.9. If you use pounds and inches, the formula becomes BMI = 703 × weight (lb) ÷ height (in)². Under WHO categories, below 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is obese.

How to read your result

A BMI in the 18.5–24.9 range is generally associated with the lowest risk of weight-related disease. Higher values raise the risk of conditions such as type 2 diabetes, high blood pressure, and heart disease, while a very low BMI can signal undernutrition. Keep in mind that BMI does not distinguish muscle from fat, so very muscular athletes may score as overweight despite low body fat. Treat BMI as one signal alongside body-fat percentage and waist circumference.

Frequently Asked Questions

What is a healthy BMI? ▾

Under WHO guidelines, a BMI between 18.5 and 24.9 is considered a healthy weight for most adults. Values below 18.5 indicate underweight and 25 or above indicate overweight.

Can BMI be used for children? ▾

No. Children's body composition changes as they grow, so paediatricians use age- and sex-specific BMI percentile charts rather than the fixed adult thresholds.

Is BMI accurate for muscular people? ▾

Not always. Because BMI uses only weight and height, very muscular people may register as overweight even with low body fat. Pair it with body-fat percentage or waist measurements.

How often should I check my BMI? ▾

There is no need to check it daily. Weighing yourself about once a week under the same conditions (e.g., in the morning before eating) is enough to track meaningful trends.

This tool provides a general health estimate and is not a substitute for professional medical diagnosis or advice. If you have any concerns about your health, please consult a qualified healthcare provider.