What is a board foot?

A board foot is the volume of a piece of lumber 1 inch thick, 12 inches wide, and 12 inches long — equivalent to 144 cubic inches. It's the standard pricing unit for rough-sawn hardwoods (oak, walnut, cherry) and is independent of the actual lumber dimensions.

Board feet = (thickness in × width in × length in) / 144. If length is in feet, multiply length-ft by 12 first, or use: BF = (thickness × width × length-ft) / 12. For multiple pieces, multiply by quantity.

Should I use nominal or actual dimensions?

Use NOMINAL dimensions (what the lumber is sold as: 4/4, 5/4, 8/4 thickness × stated width). Hardwood is usually priced on rough-sawn nominal sizing. Surfaced lumber (S2S, S4S) costs more per board foot but the BF is still calculated from nominal.

How is hardwood thickness measured?

In quarter inches: 4/4 = 1 inch, 5/4 = 1.25 in, 6/4 = 1.5 in, 8/4 = 2 in, 12/4 = 3 in, 16/4 = 4 in. Quarter-inch sizing is universal for hardwood lumberyards.

Is this the same as linear feet?

No. Linear feet measures only length and is used for trim, moulding, and dimensional softwood (2x4s, 2x6s) sold by piece. Board feet measures volume and is used for hardwoods sold by random width/length.

Lumber Board Foot Calculator

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Free board-foot calculator for hardwood and rough-sawn lumber. Enter thickness, width, length, and piece count to get total board feet, then optionally enter price per board foot for total cost. Board foot is the standard volume unit for hardwoods and rough-cut softwoods — equivalent to a 1 in × 12 in × 12 in plank.

Thickness (in)

4/4=1, 5/4=1.25, 6/4=1.5, 8/4=2

Width (in)

Length

unit

Pieces

Price per board foot ($, optional)

Formula · BF = (thickness in × width in × length in) / 144

Use nominal dimensions (rough-sawn). Hardwood is priced this way at lumberyards.

Total board feet

4.00 bf

Frequently Asked Questions

References

Wood Database — Board Foot Calculator — The Wood Database

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Frequently Asked Questions

References and sources

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