Lumber sizes can confuse first-time builders because a 2×4 doesn’t actually measure 2 inches by 4 inches. The name is the nominal size, which comes from the rough size of the board before it’s dried and planed smooth. The actual size is smaller, and knowing the difference helps avoid mistakes when planning a project.
Most common softwood lumber follows a simple pattern. Boards that are nominally 2 inches thick measure about 1-1/2 inches. Widths up to 6 inches lose about 1/2 inch, while wider boards lose about 3/4 inch. Here are the most common sizes builders use.
A 2×4 measures about 1-1/2 by 3-1/2 inches. A 2×6 measures about 1-1/2 by 5-1/2 inches. A 2×8 is about 1-1/2 by 7-1/4 inches, a 2×10 is about 1-1/2 by 9-1/4 inches and a 2×12 is about 1-1/2 by 11-1/4 inches. A 1×4 board is about 3/4 by 3-1/2 inches, and a 4×4 post is about 3-1/2 by 3-1/2 inches.
Length works differently. A board sold as 8 feet is usually close to 8 feet long, though some studs are pre-cut to fit standard wall heights. Builders should measure before cutting, since lengths can vary a little.
Hardwood lumber uses a different system. It’s often sold by thickness in quarters, like 4/4 or 8/4, and by the board foot. Widths and lengths can vary from board to board.
Understanding lumber sizes makes it easier to buy the right amount of material and avoid gaps in framing, decks and shelves. It also helps when ordering hardware like joist hangers, which are sized to match actual lumber dimensions.
For help with framing lumber and cut lists in Los Angeles, builders can visit Anawalt Lumber, a family-owned yard serving the area since 1923.
