How Do I Calculate My BMI?

How Do I Calculate My BMI

What is BMI?

BMI or Body Mass Index is used as a general indication of whether or not your overall body weight is within a healthy range. It is calculated using a person’s weight and height. 

Want to know to calculate your BMI?

It’s very simple to calculate your own BMI because only two factors are required, your height and your weight. Have a go and see how you measure up! Here’s what you need to do:

  • Divide your weight in kilograms (kg) by your height in metres (m)
  • Then divide the answer by your height again to get your BMI


For example:

  • If you weigh 70kg and you’re 1.75m tall, divide 70 by 1.75. The answer is 40.
  • Then divide 40 by 1.75. The answer is 22.9. This is your BMI.


On the BMI scale, anything below 18.5 is considered “underweight,” 18.5 to 24.9 is “normal,” 25.0 to 29.9 is “overweight” and an index of 30 or more is “obese.”

What does the result mean?

People come in all shapes and sizes so any BMI from 18.5 to 24.9 is considered to be healthy.

  • If your BMI is below 18.5, you are probably underweight.
  • Your BMI is 25 or over, you are probably overweight.
  • If your BMI is over 30, you are classified as obese. 


Being overweight and particularly being obese increases your risk of risk of heart disease, stroke and type 2 diabetes. 

How Accurate is BMI?

BMI is guidance not a magic formula and not the only factor a doctor will be interested in.

Muscle weighs more than fat so professional athletes with high muscle bulk may have high BMIs without being unhealthily overweight.

Ethnicity matters too. Because of the increased risk of diabetes in Asian men, these men are advised to keep their BMI below 23.

Although the evidence is less clear-cut, black people and other minority groups are also advised to maintain a BMI below 25 to reduce their risk of type 2 diabetes.

How do I Maintain a Healthy BMI?

Now you know what is considered a healthy BMI, don’t panic if your score is outside of the desirable range.

There are lots of small steps you can take to work towards a healthy BMI, including changes to what you eat, how you exercise, and your daily habits. 

Have a healthy, balanced diet

This means making sure your diet has the right mix of fruit, vegetables, starchy foods, and proteins, and only small amounts of high fat or high sugar foods.

Take a look at our chart to see what a balanced diet looks like.

Manage portion sizes

Only put as much on your plate as you really need to eat. It also helps to make sure that when you sit down to eat a meal, you’re able to pay it your full attention, stopping when you’re full.

Get active

Activities that increase your heart rate and breathing (known as aerobic exercise) for 150 minutes a week are recommended for maintaining a healthy weight.

Why not start a new hobby, like swimming or salsa?

You could also find a new way of getting to and from work, such as cycling and walking – the fresh air and light will also give your spirits a boost.

Cut down on alcohol 

High in calories, low in nutritional value: it’s best to enjoy alcohol in moderation. Find out the recommended limit of alcohol consumption per week here.