Brothh

What it means

A board foot (BF) is the standard unit of volume for hardwood lumber pricing. One board foot = 144 cubic inches = a nominal 1 in × 12 in × 12 in block.

Formula: BF = (thickness_in × width_in × length_ft) ÷ 12, OR (thickness × width × length_in) ÷ 144. Thickness is nominal for rough lumber (a "4/4" board is 1 in rough, ≈ 0.75 in after milling).

Examples

1 × 6 × 8 ft

(1 × 6 × 8) ÷ 12 = 4 BF

8/4 × 8 × 10 ft

(2 × 8 × 10) ÷ 12 ≈ 13.3 BF

Do

Buy rough lumber by board foot, milled dimensional lumber by linear foot.
Always round up when estimating — expect 10-20% waste in cut and rough milling.

Don't

Confuse board feet with "linear feet" — a 1×12 and a 1×6 differ in BF even at the same length.

History

The board foot dates to 19th-century US sawmills as a way to price irregular rough lumber by the lumber market in Chicago. The name comes from the visualization of a 1 ft × 1 ft × 1 in "board," though any combination that multiplies to 144 cu in qualifies.

Related terms

Kerf

The width of material a saw blade removes with each cut. Table saw ~1/8", bandsaw ~1/32", laser ~1/100".

Calculators that use this

Board Feet

Convert lumber dimensions to board feet and project cost — the standard unit for buying rough lumber.

Wood Project Cost

Add lumber, hardware, finish, and labor into a true project cost — and cost per piece if you are making multiples.

Kerf Allowance

How much material a saw blade eats across multiple cuts — ripping, crosscuts, bandsaw, laser.