BMI (Body Mass Index) is a measurement based on your weight and height.
The BMI index provides an easy way to estimate and bracket your body fat. It is a blunt instrument, which can be useful as a general guide for body fat levels for more than 80% of the population.
Calculate your BMI
Calculate your Body Mass Index (BMI) with this calculator, simply enter your weight and height.
What to do if my BMI says I’m overweight or obese?
If your BMI shows you are overweight or obese, you need to start to loose weight.
Your first step should be understand how many calories your should eat a day to loose weight, then you can start to take control and make the change you need.
What Does BMI Mean?
The BMI index gives a measurement based on your weight and height in an attempt to classify or bracket your body fat.
It is a blunt instrument, which can be useful as a general guide for body fat levels for more than 80% of the population.
The concept of a BMI index has been around since the 1800s.
Initially it was not used for studying obesity, but rather classifying people based on their physical features.
After the second world war the weight levels in the general population started to increase.
Life insurance companies saw the connection between being morbidly overweight and an increased risk of death, so adopted the body mass index as a simple practical way of quantifying a persons relative body fat and hence their risk to insure.
In 1995 BMI was adopted by the World Health Organization as a simple tool to get insights into body fat levels and trends among different populations.
The body mass index is useful as a quick and easy tool to get a general classification of your body fat levels, which is usually fairly close to accurate.
It can be useful to you, as the first step when exploring what your current weight actually means.
There are a number of limitations to using BMI, which come about because it is a blunt simple formula.
- BMI does not take pregnancy into account
- BMI does not take gender into account
- BMI does not take body fat percentage into account
- If you are shorter than the average population, you may be reflected as having a more healthy weight than reality
- If you are taller than the average population, you may be reflected as having a less healthy weight than reality
BMI formula – How is it calculated?
BMI is calculated by dividing the weight by the height squared then adjusting for imperial measurements if necessary.
A person’s BMI index is calculated by dividing their weight in kg by their height in meters squared.
FOR EXAMPLE A PERSON WEIGHING 95 KG WHO IS 183 CM WOULD HAVE A BMI OF 28:
95 / (1.83 X 1.83) = 28.36
To calculate the BMI score using imperial measures dive the weight in lbs by the height in inches squared, then multiply by 703.
FOR EXAMPLE A PERSON WEIGHTING 190 LBS WHO IS 6′ 1″ WOULD HAVE A BMI OF 25:
(190 / (73 X 73) ) X 703 = 25.06
BMI Chart for Women & Men
Below is an example of a BMI chart.
This can be used for both women and men, as BMI and the ratings are not gender specific.
- Read across the top to find your weight in lbs
- Read down to find your height in feet and inches.
- Where the two cross is the figure for your BMI
- The color coding provides your BMI range classification.
BMI Guidelines – What do the Category Ranges Mean?
Very Severely Underweight, Severely Underweight & Underweight
The World Health Organisation (WHO) classifies a person with a BMI under 18.5 as being underweight. This may indicate they have either malnutrition or some form of an eating disorder.
The classifications of:
- Very Severely Underweight
- Severely Underweight
are used as a general guide as to the level or severity of how underweight an individual is and primarily used for collecting statistics on malnutrition / famine related events or classifying impacts of eating disorders.
Normal – Healthy Weight
BMI scores in the range of 18.5 to 25 are considered a “Healthy BMI”. This is the most desirable BMI range for the general population as a whole to aim for.
BMI scores between 25 and 30 are classified as overweight, which is having more body fat than is healthy.
Within this range it is more likely individuals will start to experience the negative health implications of being overweight.
Moderately Obese, Severely Obese & Very Severely (Morbidly) Obese
Obesity is a medication classification where the extent of body fat will have a negative affect on a persons health. Across the population as a whole, people within the obese BMI classifications will start to experience body fat related health problems and which has an impact on their life expectancy.
Obesity increases the chances of experiencing many different diseases with some of the most common being:
- Heart Disease
- Type 2 Diabetes
- Sleep Apnea
Exploring you Body Fat Percentage
In exploring your BMI, you’ve started the first step in managing your weight and improving your health.
Now you have an idea of your BMI the next step is to understand what your Body Fat Percentage is.
BMI vs Body Fat Percentage
Body fat percentage is a way of measuring the portion of your body consisting of fat, vs lean body mass (muscle, bones etc)
Understanding your body fat percentage is a much more accurate way of understanding your body composition than BMI, however it can be more complex to measure without the right tools.
For example using only the BMI scale:
IMAGINE A 6′ 2″ BODY BUILDER WEIGHING 240 LBS WOULD SHOW AS BEING OBESE. IN REALITY THE BODY BUILDER MAY HAVE A VERY LOW FAT PERCENTAGE, BUT THE BMI SCALE HAS NO WAY OF KNOWING THAT.
Get yourself one of these cheap body fat percentage measuring devices* and find out how much of your body weight you actually need to shift.