The method of calculating the excess body fat is divided into two steps.
Step 1 Calculate the BMI by using formula:
Body weight (kg)/Height (m))2
| Body Mass Index (BMI) | Classification |
| Less than 18.5 | underweight |
| 18.5 - 22.9 | Normal weight |
| 23.0 – 24.9 | Overweight |
| 25.0 – 29.9 | Obesity |
| More than 30 | Extreme Obesity |
The body mass index (BMI) is only related to body weight but does not directly reflect the amount of body fat. For example, a healthy, muscular person may have a BMI in a very high range, therefore, it is necessary to calculate the body fat in the second step.
Step 2 Calculate the fat percentage, by using formula:
((1.20 X BMI) + (0.23 X Age) - (10.8 X Gender) - 5.4) ➗100 X 100%
**If male, use number 1, women use number 0
**Normally, the fat percentage in males should not exceed 22% and females should not exceed 31%
| Classification | Female | Male |
| Essential Fat | 10 – 13% | 3 – 6% |
| Athletes | 14 – 20% | 7 – 13% |
| Fitness (good) | 21 – 25% | 14 – 17% |
| Average (acceptable) | 26 – 31% | 18 – 22% |
| Overweight | 32 – 39% | 23 – 29% |
| Obese |
40% or more | 30% or more |
