What Is a Board Foot?

The short answer

A board foot is a volume of wood 1 inch thick, 12 inches wide and 12 inches long: 144 cubic inches. A board 2 inches thick and 6 inches wide holds one board foot in every foot of its length. Hardwood is almost always priced this way, and framing lumber is often tallied this way in wholesale and contractor quotes.

board feet = thickness (in) × width (in) × length (ft) ÷ 12

Board foot, linear foot and square foot

A linear foot and a board foot are the same only when thickness × width equals 12, as with a 2×6 or a 1×12. For other sizes, convert with the table below.

Why nominal size is used for framing lumber

A 2×4 is not 2 by 4 inches. It is sawn near that size, then dried and planed down to about 1½ × 3½ inches. The name, and the board-foot tally, stay with the nominal size. So an 8 ft 2×4 counts as 5.33 board feet even though the actual wood is less. Every yard uses the same convention, so prices are still comparable.

Canada uses the same names. In metric markets, a 2×4 is often described by its actual size, about 38 × 89 mm, and in Australia framing timber such as 90 × 45 mm is usually sold by the linear meter.

Hardwood and the quarter system

Hardwood is sold rough-sawn by thickness in quarters of an inch. The thickness counts at its quarter size even after the board is planed.

Hardwood boards also come in random widths. The yard measures each board and adds up the tally, so expect odd totals on the ticket.

Worked examples

A hardwood board

A 4/4 cherry board 7 in wide and 10 ft long: 1 × 7 × 10 ÷ 12 = 5.83 board feet.

A joist order

Twelve 2×8 joists for a small deck, each 12 ft long: one is 2 × 8 × 12 ÷ 12 = 16 board feet, so the order is 192 board feet, or 16 cubic feet of wood. At a quoted price of $3.50 per board foot (used here only to show the arithmetic), that is $672.00. The board foot calculator does this for any size and quantity, and shows the volume in cubic feet or m³.

A random-width hardwood tally

Three 4/4 boards, each 10 ft long, measure 5, 7 and 8 in wide. Add the widths (20 in) and treat them as one board: 1 × 20 × 10 ÷ 12 = 16.67 board feet. Yards often tally a stack this way, so you can check the ticket.

Board feet and cubic feet

Since a cubic foot is 1,728 cubic inches and a board foot is 144, there are 12 board feet in a cubic foot. That helps if you are working out the weight of a load from a species' density per cubic foot, or comparing with a metric quote in cubic meters.

Comparing prices

• To turn a per-piece price into a per-board-foot price, divide the piece price by the board feet in one piece.
• One board foot is about 0.00236 m³, and one cubic meter is about 424 board feet. Use that to compare an imperial quote with a metric one.
• Price per board foot rises with grade and often with thickness and width. Compare like with like: same species, grade, thickness and surfacing.
• For furniture projects, buy 20 to 30 percent more hardwood than the finished parts need, as a rule of thumb, to allow for knots, checks and cutting.

Frequently asked questions