BMI Calculator
Use our BMI calculator to calculate your Body Mass Index based on your height and weight. This tool allows you to choose between metric and imperial measurements and provides both your BMI score and a general category classification.
Enter your details below to see your BMI result and whether it falls into the underweight, healthy, overweight or obese range. This calculator is intended for general guidance and awareness only.
Enter your details below to see your BMI result and whether it falls into the underweight, healthy, overweight or obese range. This calculator is intended for general guidance and awareness only.
Advertisement
Advertisement
Disclaimer: This calculator provides general estimates only and is not a substitute for medical advice. Last checked/updated February 2026.
More Calculators
How the BMI Calculator Works
This calculator uses a standard Body Mass Index formula to estimate body weight relative to height. You can enter your measurements using either metric or imperial units.
The calculator uses:
The calculator uses:
It then calculates your BMI value and assigns a general category based on commonly used BMI ranges.
Example 1: A Standard Calculation
If a person is 1.75m (5ft 9in) tall and weighs 70kg (154 lbs):
– The calculator divides the weight by the height squared (70 ÷ 1.75²).
This results in a BMI of 22.9, which places them in the ‘Healthy weight’ category.
Example 2: The Athlete Exception (Why BMI isn’t perfect)
If a professional rugby player is 1.80m tall and weighs 105kg due to heavy muscle mass:
– The calculator will return a BMI of 32.4, which technically falls into the ‘Obese’ category.
Takeaway: Because muscle is much denser than fat, BMI often overestimates health risks in highly muscular athletes, which is why it should only be used as a general baseline.
Example 1: A Standard Calculation
If a person is 1.75m (5ft 9in) tall and weighs 70kg (154 lbs):
– The calculator divides the weight by the height squared (70 ÷ 1.75²).
This results in a BMI of 22.9, which places them in the ‘Healthy weight’ category.
Example 2: The Athlete Exception (Why BMI isn’t perfect)
If a professional rugby player is 1.80m tall and weighs 105kg due to heavy muscle mass:
– The calculator will return a BMI of 32.4, which technically falls into the ‘Obese’ category.
Takeaway: Because muscle is much denser than fat, BMI often overestimates health risks in highly muscular athletes, which is why it should only be used as a general baseline.
What Is Body Mass Index (BMI)?
Body Mass Index is a numerical value used globally to classify weight status. While guidelines can vary slightly by region, the World Health Organization (WHO) typically defines the categories as:
These categories are used as general indicators and do not account for factors such as muscle mass, body composition or individual health conditions.
For more detailed guidance on healthy weight, visit the official NHS website.
For more detailed guidance on healthy weight, visit the official NHS website.
When Should You Use a BMI Calculator?
This calculator is useful when you want to:
Advertisement
About This BMI Calculator
This BMI calculator uses standard BMI formulas and classification ranges commonly referenced by health organisations. It is designed to provide an easy-to-understand result using simple inputs.
BMI is a general screening tool only and does not diagnose health conditions. Individual health assessments should always be discussed with a qualified professional.
BMI is a general screening tool only and does not diagnose health conditions. Individual health assessments should always be discussed with a qualified professional.
Frequently Asked Questions
What does my BMI result mean?
Your BMI result places you into a general category such as underweight, healthy, overweight or obese based on standard ranges.
Is BMI an accurate measure of health?
Can I use this calculator with imperial measurements?
Is this calculator free to use?
Should I rely on BMI for medical decisions?
Disclaimer
This calculator provides general information only and should not be used as medical advice.
Last checked/updated February 2026.
Last checked/updated February 2026.