Frequently Asked Questions

Multiply thickness (in) × width (in) × length (ft), then divide by 12. If length is measured in inches, divide by 144 instead. For example, a 2" thick by 6" wide board that is 10 feet long contains (2 × 6 × 10) ÷ 12 = 10 board feet.

A 2x4 that is 8 feet long contains approximately 5.33 board feet, calculated as (2 × 4 × 8) ÷ 12 = 5.33 BF using standard nominal dimensions.

A board foot calculator is an online tool that converts the thickness, width, length, and quantity of lumber into board feet (BF), the standard volumetric unit used by sawmills and suppliers to price and measure wood.

At 1 inch thick (4/4 stock), 200 board feet covers exactly 200 square feet of surface area. Thicker lumber covers less area for the same board footage: at 2 inches thick, 200 BF covers 100 square feet, because board feet measures volume rather than surface area.

A 4-foot by 8-foot sheet is 32 square feet (4 × 8 = 32 sq. ft.). This is the universal dimension for standard plywood, MDF, OSB, and drywall panels in North America.

Linear feet measures only the length of a board regardless of its width or thickness (e.g., a 10-foot board is 10 linear feet whether it is a 2x4 or a 2x12). Board feet measures three-dimensional volume (thickness × width × length). A 10-foot 2x4 has 6.67 BF, while a 10-foot 2x12 has 20 BF.

Nominal size is the rough-sawn dimension before drying and surfacing (planing). Actual size is the final finished dimension. For example, a nominal 2x4 is surfaced down to 1 1/2" × 3 1/2". In the lumber trade, board footage is virtually always calculated against nominal sizes.

Hardwood mills express thickness in quarters of an inch of rough-sawn lumber. 4/4 ('four-quarter') is 1 inch thick; 5/4 is 1.25 inches thick; 6/4 is 1.5 inches thick; 8/4 is 2 inches thick; and 12/4 is 3 inches thick.

MBF stands for 'Thousand Board Feet' (M is the Roman numeral for 1,000). Commercial sawmills, wholesalers, and timber brokers quote bulk framing lumber in $/MBF. For example, $850/MBF equals $0.85 per board foot.

For rough hardwood lumber, add 15% to 20% extra board footage for standard straight-grained projects to account for sapwood, knots, checks, and saw kerf. For highly figured wood, curved parts, or intricate moldings, plan for a 25% to 30% waste factor.

Round logs are calculated using log scaling rules (such as the Doyle, Scribner, or International 1/4-Inch log rules) which account for the conical taper and bark loss to estimate the net board feet of rectangular lumber the log will yield.