RapidCheck

BMI Calculator

Check your Body Mass Index (BMI) and see whether you are underweight, normal, overweight or obese.

Last updated: 8 Aug 2026

Quick answer

Your BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). A BMI of 18.5–24.9 is a healthy weight, below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. Enter your height and weight above to calculate it instantly.

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Body Mass Index (BMI) is a simple screening number that relates your weight to your height. It is calculated as weight (kg) ÷ height (m)² and gives a quick indication of whether your weight is in a healthy range for your height. Enter your details below to calculate your BMI instantly — nothing is sent to a server.

How to calculate your BMI

  1. 1 Choose metric (cm/kg) or imperial (ft-in/lb) units.
  2. 2 Enter your height and weight.
  3. 3 We compute BMI = weight ÷ height² and match it to the WHO category.
  4. 4 Results are calculated in your browser and never leave your device.

Frequently asked questions

What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). For imperial units, BMI = 703 × weight(lb) ÷ height(in)².
Is BMI accurate for everyone?
BMI is a useful general screening tool but it does not distinguish muscle from fat. Athletes may show a high BMI despite low body fat, and it is not intended for children, pregnant people, or the elderly without clinical context.
Does this BMI calculator store my data?
No. The calculation runs entirely in your browser using JavaScript. Your height and weight are never sent to or stored on our servers.

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