BMI is an acronym for Body Mass Index, and it is used as a tool for screening patients as it is believed to indicate if the weight of an individual is within normal limits according to their height. So, as mentioned, to calculate the BMI, the parameters needed are the weight and the height put in the following formula: BMI = kg/m2, for the metric system. In other words, BMI’s main purpose is to diagnose different stages of obesity, but the Body Mass Index alone cannot replace the more specific medical tests for this condition, which should be taken whenever the first assessment of the quickly done BMI indicated towards the diagnosis of obesity.
Either the metric or the imperial systems of the BMI calculator can be used to obtain the measure of one’s body size and composition, but the BMI calculator formula must be changed accordingly:
- BMI calculator in metric: BMI = kg/m2
With the metric system, the heigh can be in meters or centimeters.If the individual height is measured in centimeters, it must be converted to meters, dividing it by 100, because the kg-cm BMI calculator doesn’t exist.
- BMI calculator in imperial: BMI = lbs. x 703/in2
BMI |
Nutritional status |
<18.5 |
Underweight |
18.5-24.9 |
Normal weight |
25.0-29.9 |
Pre-obesity |
30.0-34.9 |
Obesity class I |
35.0-39.9 |
Obesity class II |
>40 |
Obesity class III |
Smart Body Mass Index |
Nutritional assessment |
Weight-related level of risk |
0/70 – 9/70 |
Extreme anorexia |
Very high risk |
10/70 – 19/70 |
Anorexia |
High risk |
20/70 – 29/70 |
Moderate to underweight |
Moderate risk |
30/70 – 39/70 |
Normal weight |
Low risk |
40/70 – 49/70 |
Moderate overweight |
Moderate risk |
50/70 – 59/70 |
Overweight to obesity |
High risk |
60/70 – 70/70 |
Morbid obesity |
Very high risk |
Women |
Men | ||
Age |
Body fat percentage |
Age |
Body fat percentage |
18 to 21 |
33% |
18 to 21 |
22% |
22 to 29 |
34% |
22 to 29 |
23% |
30 to 39 |
35% |
30 to 39 |
24% |
Over 40 |
36% |
Over 40 |
26% |
% of body fat |
Minimal amount |
Healthy amount |
Healthy FFM |
Men |
3% |
10-22% |
78-90% |
Women |
12% |
20-32% |
68-80% |