CREFF Formula

Not Reviewed
Equation / Last modified by KurtHeckman on 2018/06/18 13:41
MichaelBartmess.CREFF Formula

The CREFF Formula calculator computes a person's ideal weight based on the CREFF formula which uses a person's height (ht), age (A) and a physical factor (M) on the body type.

INSTRUCTIONS: Choose units and enter the following:

  • (A) This is the age of the person.
  • (ht) This is the height of the person (Minimum of 92 cm)
  • (M) This is morphology factor based on a physical characteristic (see below).  Choose one from the menu.

Ideal Weight: The calculator returns the weight in kilograms.  However, this can be automatically converted to other units (e.g. pounds) via the pull-down menu.

Related Calculators:

  • (BMI)  To compute the body mass index, CLICK HERE.
  • (BMI Interpreted) To compute an interpreted result of BMI, CLICK HERE.

The Math / Science

This physiology equation computes an approximation of the Ideal Weight of a human.  Experts have come up with many different ways to estimate a person's ideal weight (e.g. Body Mass Index).  This is just one of many but this equation takes into account body morphology.

The CREFF formula is as follows:

                                             `IW = ht - 100 + \frac{A}{10} * 0.9 * M`


  • IW is the Ideal Weight (CREFF)
  • ht is the height of the person
  • A is the age of the person in years
  • M is the body morphology factor

Body Mass Index (BMI) and ideal weight calculators derive their equations from empirical data.  A clinical professional gathers data on healthy individuals and then fits an equation to the data.  The CREFF equation is no different.  Because the data is fit to a set of data derived from a study of normal individuals, the data will not cover the entire range of all body types, or ages. 

Morphology Factor (M)

To determine what body type one should consider the person.  To use an appropriate factor (M), place the middle finger and thumb of your right hand around your left writs:

  1. Select Small if your thumb slightly overlaps your middle finger.  (M = 0.9)
  2. Select Average if you thumb and finger just touch. (M = 1.0)
  3. Select Broad if your thumb and finger do not touch. (M = 1.1)