Board Foot Calculator (Metric)
Calculate total board feet for hardwood or lumber from the thickness, width, length, and quantity, plus the cost at your price per board foot.
What your result means
A board foot is a volume of lumber: 144 cubic inches, or a piece 2.5 cm thick, 30.5 cm wide, and 1 foot long. Total board feet is the volume across all your pieces, and the cost multiplies that by your price per board foot. Hardwood is priced this way; dimensional softwood is often sold by the piece. Building stairs or framing? Pair this with our stair calculator.
How to use this calculator
- Enter the board thickness in inches (use nominal thickness).
- Enter the width in inches and length in feet.
- Enter how many identical boards you need.
- Add a price per board foot for a cost estimate.
- Read total board feet, cost, and board feet per piece.
The formula
Thickness times width (both inches) times length (feet), divided by twelve, gives board feet per piece, since one board foot equals 144 cubic inches. Multiply by quantity for the total.
Worked example
A 2.5 cm by 15.2 cm board, 2.4 m long, is 1 × 6 × 8 / 12 = 4 board feet. Ten of them total 40 board feet. At $5 a board foot, that's about $508 cm lumber.
Board feet for common boards (per piece)
| Board | Length | Board feet |
|---|---|---|
| 1 × 4 | 2.4 m | 2.67 |
| 1 × 6 | 2.4 m | 4.00 |
| 2 × 4 | 2.4 m | 5.33 |
| 2 × 6 | 2.4 m | 8.00 |
| 1 × 12 | 3 m | 10.00 |
Tips & gotchas
- Use nominal dimensions for ordering, but remember a 2×4 actually measures 1.5 × 8.9 cm.
- Hardwood is sold by the board foot; framing softwood is usually priced per piece.
- Quarter system: 4/4 means 2.5 cm thick, 8/4 means 5.1 cm, in the rough.
- Add 15-20% for waste, defects, and cutting on hardwood projects.
- Prices vary by species and grade — get a current quote for your wood.
Frequently asked questions
How do I calculate board feet?
Multiply thickness (in) by width (in) by length (ft) and divide by 12. A 1 by 6 board, 2.4 m long, is 4 board feet.
What is a board foot?
A unit of lumber volume equal to 144 cubic inches — a piece 2.5 cm thick, 30.5 cm wide, and 1 foot long.
Is board foot the same as linear foot?
No. A linear foot measures length only; a board foot measures volume, accounting for thickness and width too.
How much waste should I add?
Plan on 15 to 20% extra for hardwood to cover defects, cuts, and grain matching.
Why is a 2x4 not actually 2 by 4?
Nominal sizes are named before the board is dried and planed. A finished 2x4 measures about 1.5 by 8.9 cm.
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