BMI Calculator: Check your BMI

Body Mass Index is a simple calculation using a person’s height and weight

How to calculate Body Mass Index

Body Mass Index is a simple calculation using a person’s height and weight. The formula is BMI = kg/m2 where kg is a person’s weight in kilograms and m2 is their height in metres squared.

A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9. BMI applies to most adults 18-65 years.

What is BMI Calculator?

BMI Calculator is free app that allows you to monitor BMI and percentage of fat in your body.

Ideal weight - app calculates the ideal weight you should gain.

To calculate it app uses the D. R. Miller formula.

Body fat percentage is estimated from BMI by formula derived by Deurenberg and co-workers.

All measurements use information about your body: gender, age, height and weight.

App is designed for people of different ages and supports for both metric and imperial.

Who shouldn't use a BMI calculator

BMI is not used for muscle builders, long distance athletes, pregnant women, the elderly or young children. This is because BMI does not take into account whether the weight is carried as muscle or fat, just the number. Those with a higher muscle mass, such as athletes, may have a high BMI but not be at greater health risk. Those with a lower muscle mass, such as children who have not completed their growth or the elderly who may be losing some muscle mass may have a lower BMI. During pregnancy and lactation, a woman's body composition changes, so using BMI is not appropriate.

BMI ranges:

For most adults, an ideal BMI is in the 18.5 to 24.9 range.

For children and young people aged 2 to 18, the BMI calculation takes into account age and gender as well as height and weight.

If your BMI is:

below 18.5 – you're in the underweight range

between 18.5 and 24.9 – you're in the healthy weight range

between 25 and 29.9 – you're in the overweight range

between 30 and 50 – you're in the obese range

Accuracy of BMI

BMI takes into account natural variations in body shape, giving a healthy weight range for a particular height.

As well as measuring your BMI, healthcare professionals may take other factors into account when assessing if you're a healthy weight.

Muscle is much denser than fat, so very muscular people, such as heavyweight boxers, weight trainers and athletes, may be a healthy weight even though their BMI is classed as obese.

Your ethnic group can also affect your risk of some health conditions. For example, adults of Asian origin may have a higher risk of health problems at BMI levels below 25.

You should not use BMI as a measure if you're pregnant. Get advice from your midwife or GP if you're concerned about your weight.

Track your BMI and stay healthy!