|Nominal||Surfaced 1 Side (S1S)||Surfaced 2 sides (S2S)|
|1⁄2 in||3⁄8 in (9.5 mm)||5⁄16 in (7.9 mm)|
|5⁄8 in||1⁄2 in (13 mm)||7⁄16 in (11 mm)|
|3⁄4 in||5⁄8 in (16 mm)||9⁄16 in (14 mm)|
|1 in or 4⁄4 in||7⁄8 in (22 mm)||13⁄16 in (21 mm)|
|1 1⁄4 in or 5⁄4 in||11⁄8 in (29 mm)||11⁄16 in (27 mm)|
|1 1⁄2 in or 6⁄4 in||13⁄8 in (35 mm)||15⁄16 in (33 mm)|
|2 in or 8⁄4 in||113⁄16 in (46 mm)||13⁄4 inches (44 mm)|
|3 in or 12⁄4 in||213⁄16 in (71 mm)||23⁄4 in (70 mm)|
|4 in or 16⁄4 in||313⁄16 in (97 mm)||33⁄4 in (95 mm)|
In North America, sizes for dimensional lumber made from hardwoods varies from the sizes for softwoods. Boards are usually supplied in random widths and lengths of a specified thickness, and sold by the board-foot (144 cubic inches or 2,360 cubic centimetres, 1⁄12th of 1 cubic foot or 0.028 cubic metres. This does not apply in all countries, for example in Australia many boards are sold to timber yards in packs with a common profile (dimensions) but not necessarily consisting of the same length boards. Hardwoods cut for furniture are cut in the fall and winter, after the sap has stopped running in the trees. If hardwoods are cut in the spring or summer the sap ruins the natural color of the timber and decreases the value of the timber for furniture.
Also in North America, hardwood lumber is commonly sold in a "quarter" system when referring to thickness. 4/4 (four quarters) refers to a 1-inch-thick (25 mm) board, 8/4 (eight quarters) is a 2-inch-thick (51 mm) board, etc. This system is not usually used for softwood lumber, although softwood decking is sometimes sold as 5/4 (actually one inch thick).