See dimensional lumber for a full discussion of the relationship of actual and nominal dimensions. Briefly, for softwoods, to convert nominal to actual, subtract 1⁄4 inch (6 mm) for dimensions under 2 inches; subtract 1⁄2 inch (13 mm) for dimensions over 2 inches and under 8 inches; and subtract 3⁄4 inch (19 mm) for larger measurements. The system is more complicated for hardwoods.