Why is lumber sold this way?

Because hardwood comes in random widths and lengths. Selling by volume makes price comparable across boards that are not the same shape.

Four quarters of an inch, so one inch rough thickness. After planing it finishes around thirteen-sixteenths, but it is priced as one inch.

Construction & HomematerialsUnited States only

Board Foot / Lumber Calculator

Board feet for hardwood lumber, which is sold by volume rather than by length. One board foot is 144 cubic inches, and nominal sizes are not actual sizes.

Also called: lumber calculator, bf calculator.

Board feet

40 board feet across 10 pieces. One board foot is 144 cubic inches, so a 1 by 12 that is a foot long is exactly one.

Board feet per piece

Cubic feet

3.33

Cubic metres

0.09

Cost at your price

$0.00

Total linear feet

How this is calculated

Method and background

How this is calculated

A board foot is a volume: one inch thick, twelve inches wide, one foot long. Multiply thickness in inches by width in inches by length in feet and divide by twelve. The trap is nominal versus actual dimensions: a nominal one-inch board is planed to three quarters, but hardwood is normally sold by the rough thickness in quarters, so 4/4 means one inch rough.

board feet = thickness in inches * width in inches * length in feet / 12

t: Thickness (inches)
w: Width (inches)
l: Length (feet)

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

ten one-by-six boards eight feet long

Thickness (inches): 1
Width (inches): 6
Length (feet): 8
Pieces: 10
Price per board foot: 0

Board feet40

1 * 6 * 8 / 12 = 4 board feet each

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the definitional board foot

Thickness (inches): 1
Width (inches): 12
Length (feet): 1
Pieces: 1
Price per board foot: 0

Board feet1

boundary: 144 cubic inches by definition

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thicker stock is proportionally more

Thickness (inches): 2
Width (inches): 6
Length (feet): 8
Pieces: 1
Price per board foot: 0

Board feet8

degenerate case

Open this example

Method and limits

What it assumes

Dimensions entered are the ones the price is quoted against.

What it deliberately does not model

Softwood is usually sold by linear foot at nominal dimensions instead, which this does not model.
Waney edges and defects mean usable yield is below purchased board feet.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why is lumber sold this way?: Because hardwood comes in random widths and lengths. Selling by volume makes price comparable across boards that are not the same shape.
What does 4/4 mean?: Four quarters of an inch, so one inch rough thickness. After planing it finishes around thirteen-sixteenths, but it is priced as one inch.