The body mass index (BMI for short), is a simple mathematical measure involving a person’s height and weight, and it’s used to determine healthy weight ranges for humans. BMI is an important number for scientists and physicians and is best used as a general guide. Many people have dealt with this number, voluntarily or involuntarily.

The BMI calculator, discovered by the Belgian polymath Adolphe Quetelet between 1830 and 1850, evaluates the bodyweight of a person.

body mass index calculator

The Body Mass Index Calculator

Use our calculator below to calculate your body mass index.

BMI Calculator



Your BMI is:


The BMI Weight Categories

BMI Classification
less than 18.5: Underweight
18.5 – 24.9: Normal weight
25 – 29.9: Overweight
30 – 34.9: Class I Obese
35 – 39.9: Class II Obese
40 upwards: Class III Obese

Benefit of BMI

The main benefit of the index is to point out and warn of possible overweight or for someone who is at the risk of obesity. The risk of being overweight is increasing among the world’s population at a rapid pace. The BMI calculator used to measure your BMI value takes into account the individual’s weight, but not the composition of muscle and fat tissue. 

How to calculate BMI

The BMI calculation is very simple and its obtained from 2 different measuring units. We have the imperial measurement and Metric measurement.

Imperial Measurement: The BMI value equals the weight in pounds, divided by the square of the height in inches, then multiplied by 703.

BMI = 703 x weight(lb)/height² (in)

Metric Measurement: The BMI value equals weight in kilograms, divided by the square of the height in meters.

BMI = weight(kg)/height²(m)

If the body mass index is below 18.5, then that person is considered to be underweight. Between 18.5 and 25, the weight is considered normal and not conspicuous. Those with BMI values over 25 are considered overweight, and caution is recommended at this point. Such people have a slight tendency to be overweight. BMI values above 30 indicate possible health problems and this must be taken seriously since they are already in the obese range.

The BMI takes the age of a person into account. The normal value for those under 30 years old lies below that of the older generation. Also, gender plays an important role. Studies show that BMI among men is considerably higher than that of women, and this is generally attributed to men having more muscle mass.

Constant monitoring of one’s weight is so important, especially among children and adolescents. Many of them tend to be slightly overweight even at a younger age, which has a negative impact on bones and development.


Anyone that is slightly underweight is not expected to take any extreme measures to gain weight. It is recommended you spend more time eating lots of calories throughout the day. There is also weight gain shakes you incorporate into your daily meal to help bring your weight up to a healthy level.

If you are at the extreme underweight level, you may be lacking proper healthy nutrition. Such persons should consult their doctor or a nutritionist for further advice.

Normal Weight

Those in the normal weight range, this indicates you have healthy body weight. It is recommended that you keep living a healthy lifestyle, eat a healthy meal to help maintain your weight.


Studies show that more than 32.5% of American adults are overweight, and this number could continue to rise at an alarming rate. Nevertheless, there are some overweight people who are healthy, while the majority of them do have underline health challenges. Note that the higher your BMI value, the higher the risk of that person having certain health issues, such as high blood pressure, diabetes, heart disease, breathing problems, and in some cases cancer. For those who are overweight, you are recommended to go for a weight loss program.


More than one-third of American adults are considered obese. The risk associated with obesity varies with long-term health problems, and this includes high blood pressure, heart disease, diabetes, stroke, and many more. At this stage, you are strongly advised to see a doctor, nutritionist, fitness expert to recommend you a weight loss plan.

Is BMI really reliable?

BMI is currently used by the World Health Organization as its standard metric for assessing weight issues, but it is a broad calculation and does have some exceptions. BMI is typically most useful to adults between 18 and 64. BMI is not valid for children, seniors, pregnant women, and athletes.

Easy Weight Loss Tips

If your BMI value indicates you are either overweight or obese, I would recommend the following easy weight loss tips to help you kick start your weight loss program.

  • Go walking from time to time and where possible avoid using car
  • Drink water as much as you can daily and avoid sugary drinks
  • Use a smaller plate when you are about to have your meal
  • Be patient and continue to believe in yourself
  • Learn to eat at the same time every day
  • Eat only when you are hungry
  • Avoid mindless eating or junk food
  • Eat protein rich meals
  • Keep healthy foods and snacks at home
  • When eating outside or in a restaurant, order small portions
  • Do not use food as a way of coping with stress
  • Stay physically active majority of the day
  • Learn to keep a food diary
  • Eat more vegetables
  • Avoid foods that contain sugar, corn syrup or fructose
  • Don’t eat too fast but slowly
  • Take in more fruits instead of drinking fruit juices
  • Eat more in the morning than in the evening
  • Watch less TV and stay of social media from time to time
  • Eat a balanced breakfast
  • Cut back on alcohol
  • Get enough sleep as this is very important
  • Cut down on liquid calories