How you can calculate the knit fabric T-shirt consumption?

Consumption in grams= {(L*C) + (C*SL)}*2*GSM/10000 grams (when length units are in centimeter). This is a basic function to find the fabric consumption of a knit t-shirt. The key is C= Chest, L= length of the body measure, SL= Sleeve length , B=Biceps , GSM = fabric weight in grams per square meter. Be sure to include the allowances in all fabric measurements.