The Body Mass Index, or BMI, is considered worldwide as one of the best ways to measure an individual’s health based on their weight. By calculating your Body Mass Index, you can gauge how well your diet and routine physical activity are helping you maintain a healthy weight and keeping you from being overweight or underweight.

intro calculate body mass index


A BMI scale provides information about whether your body weight is appropriate for your height. The method involves considering your body weight in kilograms (Kg) and height in meters and dividing the weight by the square of the height. The resulting figure is your BMI or Body Mass Index.

Body Mass Index Scale

  • BMI below 18 → Underweight
  • BMI between 18 to 18.5 → Lean or thin for your height
  • BMI between 18.5 to 24.9 → Healthy
  • BMI between 25 to 29.9 → Overweight
  • BMI of above 30 or above → Obese

If you’ have seen Christian Bale in “The Machinist,” “Batman” and “American Hustle,” you will relate to the difference in his BMI for the respective roles. He went from underweight to healthy and from healthy to overweight. It might give you an idea about what these three categories look like.

Steps to Calculate Your Body Mass Index

Step 1. Measure your weight

Measure your weight

You can use an ordinary bathroom scale to take your weight.


Most people are unaware of the perfect time to measure their body weight. It is just after you come out of the bathroom in the morning.

It is important to keep the scale on a flat surface and, if you have a digital scale, in a place where the temperature remains constant throughout the day.

The general formula for BMI considers weight in Kg. Although, if your scale shows weight in pounds, no need to worry. You can still calculate your BMI easily, as mentioned later.

Step 2. Measure your height

Measure your height

You can use an ordinary measuring tape to measure your height. Getting help from another person will give you a more accurate result.

Just stand upright on your barefoot, with your feet together and heels touching the wall. Take something that has a flat surface, put it on your head, and perpendicular to the wall. If needed, ask someone to hold it for you.


Mark the wall where the lower edge of the flat surface touches the wall. Then, measure the distance from the ground to that mark using a measuring tape.

The general formula for BMI considers height in meters. Although, if your tape shows height in feet and inches, no need to worry. You can still calculate your BMI easily, as mentioned later.

Step 3. Compute your BMI

The formulas for calculating your BMI in either imperial or metric units are below. You can do the calculation manually or use a calculator.

calculate bmi


Alternatively, you can enter your weight and height into the online Body Mass Index Scale tool to calculate your BMI, or double check your math!

Additional helpful tips

  • BMI is not the only the measurement of your health. Sometimes, an individual in a healthy BMI range can have excess body fat. Consider your BMI along with your waist measurement to assess your health risks.
  • After calculating your BMI, consult a doctor before forming any kind of judgment about your health condition.
  • People of different ethnicities are vulnerable to different kinds of risks. Moreover, many health risks are a sum of multiple factors.
  • Before weighing yourself, check the accuracy of the scale by putting a 5-pound weight on it.
  • Exercising daily will help both underweight and overweight individuals get back into the healthy weight range for their height.
  • BMI is not accurate for children, and not always accurate for bodybuilders, teenagers, elderly people or pregnant women.