Leather is sold in square feet.To calculate the area in sq.ft required for you project, measure the total length and width of all your pattern pieces in cm. To calculate the area, multiply the values of length x width to get total area in square cm.e.g. (L*W) = total cm2 Divide the total square cm by 929 to convert to square feet (total cm2 / 929) = total sq.ftMultiply the total sq. ft by the number of units you want to produce to get your total leather requirement. Note: leather is a natural product some inconsistencies are to be expected as well as irregular shapes so it pays to plan for at least 20% additional area to make sure your pieces will fit.Please note this calculation is to be used as a guide only. Customers are responsible for ensuring the correct quanities