Bmi Calculator

How to Calaulte the BMI

BMI is defined as the body mass with unit of kg divided by the square of the body height with unit of meter in metric units. Therefore, if you select Metric units, the formula is: \[ BMI = \frac{Mass}{Height^2} (\frac{kg}{m^2})\] If you select US units, we will need to convert it into metric units firstly and then apply the formula. Since 1 pound = 0.453592 kg and 1 inch = 2.54 cm, given weight in unit of pound and height in units of inches, the BMI formula will be: \[BMI = \frac{0.45592\times Mass}{(\frac{2.54 \times Height}{100})^2} = 703 \times \frac{Mass}{Height^2} \]

How to Calculate BMI Prime

BMI Prime is defined as the ratio of your BMI to the up limit of health BMI that is defined as 25. Therefore, the BMI Prime is calculated based on this formula: \[ BMI Prime = \frac{BMI}{25}\]

How to Calculate Corpulence Index (CI)

Corpulence Index (CI) or Ponderal Index (PI) is defined as the body mass with unit of kg divided by the cubic of the body height with unit of meter. The argument for using cubic instead of square is that human body should be considered as volume instead of area units. The formula is: \[ CI = \frac{Mass}{Height^3} (\frac{kg}{m^3}) \] For US Units, like in the BMI case, we can convert the unit and then apply the metric unit formula.

How to Calculate Body Fat based on BMI

Body fat percentage (BFP) formula for adult males:
BFP = 1.20 × BMI + 0.23 × Age - 16.2
Body fat percentage (BFP) formula for adult females:
BFP = 1.20 × BMI + 0.23 × Age - 5.4
Body fat percentage (BFP) formula for boys:
BFP = 1.51 × BMI - 0.70 × Age - 2.2
Body fat percentage (BFP) formula for girls:
BFP = 1.51 × BMI - 0.70 × Age + 1.4

Application of BMI

In public health BMI can serve as a vague means of estimating adiposity. It is suitable for recognizing trends within sedentary or overweight individuals.

In Clinical practice, BMI is generally used to figure out whether an individual is underweight, overweight or obese.

Limitation of BMI

BMI does not work well when the height is too small or too large that is because the formula takes the square of the height. BMI also does not consider the variation in physical characteristics and does not differentiate between muscle mass and fat mass.

BMI Alternatives

Waist circumference is a good indicator of visceral fat. Waist to height ratio (WHtR), also called waist to stature ratio (WSR) is a measure of the distribution of body fat. Waist to Hip Ratio (WHR) is the ratio of the circumference of the waist to that of the hips. WHR has been used as an indicator or measure of health and risk of developing health related problems. Use Ultimate (for all) Calculator to calculate these values.

Body Shape Index (ABSI) was developed by city college of New York based on the observation that carrying excess belly fat is more risky for your health. Refer to Ultimate (for all) Calculator for the detail.

Surface Based Body Shape Index (SBSI) is based on four key measurements: the body surface area (BSA), vertical trunk circumference (VTC), waist circumference (WC) and height (H) is considered as a better indicator of the body shape. Many studies found that the SBSI outperformed BMI, WHtR and ABSI. You can use Ultimate (for all) Calculator to calculate this index.