How to use it
- Choose the Units: inches and feet on the imperial setting, millimetres and metres on the metric one.
- Enter the Thickness, the Width and the Length of one piece.
- Enter the Number of pieces.
- Read Board feet and Volume in cubic metres.
How board feet are counted
A board foot is a piece of wood 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches. Penn State Extension gives the formula for any piece: the thickness in inches times the width in inches times the length in feet, divided by 12.
The volume in cubic metres follows from the inch, which is exactly 0.0254 m. One board foot is therefore 144 × 0.0254³ = 0.00235974 m³, and the board feet are multiplied by that figure.
board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12
board feet = board feet per piece × number of pieces
volume (m³) = board feet × 144 × 0.0254³ = board feet × 0.00235974What the count does not include
- The grade and the defects of the lumber. A board with knots or a damaged edge gives less usable wood than its volume suggests.
- The log or the stack of timber. The tool measures the pieces you enter, not a log and its scaling rule.
- The price. The tool gives the volume; the price per board foot is the seller's.
Worked example: 10 pieces of 2 × 6 in, 12 ft long
One piece is 2 × 6 × 12 ÷ 12 = 12 board feet, so 10 pieces are 120 board feet.
120 × 0.00235974 m³ = 0.283 m³.
| Result | |
|---|---|
| Board feet per piece | 12.00 |
| Board feet, 10 pieces | 120.00 |
| Volume in cubic metres | 0.283 m³ |
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume: 144 cubic inches of wood, the same as a board 1 inch thick, 12 inches wide and 12 inches long. Penn State Extension explains it for timber.
Why is the length divided by 12 when it is in feet?
A board foot is 1 × 12 × 12 inches. With the length in feet, one of the 12s is already in the length, so the thickness and width in inches are multiplied by the length in feet and divided once by 12. That gives the same answer as dividing by 144 with the length in inches.
Is a board foot the same as a cubic foot?
No. A cubic foot is 1,728 cubic inches, which is 12 board feet. A board foot is the smaller unit that suits boards, while a cubic foot suits solid volumes.
Are the sizes I enter nominal or actual?
The tool uses the sizes you type. Ask the seller whether the sizes are the nominal sizes the lumber is sold by or the actual sizes after planing, because the result depends on which you enter.
Does the tool store what I enter?
No. The calculation runs in your browser, and nothing you type is sent to us or stored.
Sources
- Penn State Extension: Valuing Standing Timber (board foot definition and formula)
- NIST: U.S. Survey Foot: Revised Unit Conversion Factors (international foot 0.3048 m, exact)
Figures and text last checked on Thursday, November 12, 2026.