Wood sizing secrets exposedLast Updated:[11/27/2006 3:47:25 PM]I wondered why the wood sizes posted on the tags at the lumber store never seemed to match the measurements I take at home. I couldn't keep wondering, so after a little research here is the answer. "Listed" vs. "Actual" sizeTake a common 2 x 4 board for example. A "two by four" isn't really 2 inches by 4 inches! The actual size is closer to 1 1/2 inches by 3 1/2 inches. What the heck is going on here? Is the lumber store trying to get a little extra change from my pocket? one-inch isn't really one-inchAll wood starts off at the lumber mill green. Meaning it hasn't been air or kiln dried. When the lumber is dried it naturally shrinks. The lumber industry maintains that nominal and actual size differences can be accounted for during the finishing and drying processes. I think it is interesting to note that houses constructed more that 50 years ago have wood that is very close in nominal and actual sizes. Softwood Sizes
Softwoods generally come in standard recognizable sizes. The most common softwoods found in home improvement stores are Pine and Cedar. This chart shows the most common and advertised sizes along with the actual size in inches.
Hardwood sizes are more complicated because it depends on whether the stock is surfaced as S1 or S2 (one side or two). Hardwoods are not usually available in standard sizes. Hardwood lumber is sold by the board foot in random lengths. It is also common to see hardwood sold in quarters. 1/4-inch is the unit of measure so 5/4 would be 1 1/4-inch.
Plywood is available in 4 x 8 sheets. Plywood thickness is also a little misleading, 1/2-inch plywood is really 15/32-inch and 3/4-inch plywood is really 23/32-inch. Related Articles
Board Foot Calculation
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