How is the length of high tensile bolts calculated?

Length of high tensile bolt screw = 2 thicknesses of connecting end plates + – – thickness of nuts + 2 thicknesses of washers + 3 lengths of fillets.
Length of high tensile bolt screw = 2 thicknesses of connecting end plates + – – thickness of nuts + 2 thicknesses of washers + 3 lengths of fillets.