To calculate a product’s D score easily and quickly, you can use the free Ecobalyse tool available on this page. 
All you need to do is select the product category and then complete the “Durability” section by entering the new-product price, the number of references for the corresponding market segment and your company type (very small enterprise/small or medium-sized enterprise, or Large Enterprise with or without a repair service). The durability coefficient (i.e. the D score) is displayed automatically.