That’s why he slightly modified the old formula to get a more realistic picture. The classical BMI calculation was simplified: in the 1840s, there were no calculators and everything was written on paper ( source ). This new formula of BMI is to multiply your body weight by 1.3. The new formula of BMI thus gives this: Improved BMI index = 1.3 x weight / height 2.5 In the example of our man with a weight of 95 kilos and a height of 190 cm, the old index IMC gave a result of 26.3. A slight overweight. According to the improved formula of BMI, this man now has a healthy weight, with a BMI index of 24.8. Unfortunately, this improved BMI index is unofficial and is not used by many governments. In any case, it can tell you more clearly if you have a healthy weight or not. Waist-to-waist ratio waist size Research suggests that the waist-to-waist ratio method provides a more reliable estimate of your current health status than your BMI. ( source , source , source , source ) .