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Board foot calculator
Updated October 24, 2026 · Free, no sign-up
Board feet = thickness (in) × width (in) × length (ft) ÷ 12. Add each size of board on your list, set your waste and price per board foot, and get the board feet to order and what they will cost.
How to calculate board feet
A board foot is 144 cubic inches of wood: a piece 12 inches long, 12 inches wide and 1 inch thick. To find the board feet in any board, multiply its thickness and width in inches by its length in feet, and divide by 12:
board feet = T (in) × W (in) × L (ft) ÷ 12
Example: a cherry board 1 inch thick, 6 inches wide and 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet. Ten of them are 40 board feet; at $8.50 a board foot, $340 before waste. If you measure length in inches, divide by 144 instead of 12.
Board feet of common lumber sizes
Construction lumber is priced on its nominal size (a 2x4 is sold as 2 by 4 inches, though it measures 1.5 by 3.5). Board feet per piece:
| Nominal size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1x4 | 2.67 | 3.33 | 4 | 5.33 |
| 1x6 | 4 | 5 | 6 | 8 |
| 1x8 | 5.33 | 6.67 | 8 | 10.67 |
| 1x10 | 6.67 | 8.33 | 10 | 13.33 |
| 1x12 | 8 | 10 | 12 | 16 |
| 2x4 | 5.33 | 6.67 | 8 | 10.67 |
| 2x6 | 8 | 10 | 12 | 16 |
| 2x8 | 10.67 | 13.33 | 16 | 21.33 |
| 2x10 | 13.33 | 16.67 | 20 | 26.67 |
| 2x12 | 16 | 20 | 24 | 32 |
| 4x4 | 10.67 | 13.33 | 16 | 21.33 |
Hardwood thickness: 4/4, 5/4, 8/4
Hardwood is sold rough, with its thickness in quarters of an inch: 4/4 is 1 inch, 5/4 is 1¼, 6/4 is 1½, 8/4 is 2 and 12/4 is 3 inches. Board feet are worked out on that rough thickness, so a 4/4 board planed down to ¾ inch still costs you a full inch. Widths and lengths of rough hardwood are random, which is why hardwood is priced by volume rather than by the piece.
How much waste to add
- 15 to 20% for most furniture and cabinet projects in clear hardwood.
- 25 to 35% for figured wood, matched grain, or boards with knots, checks and sapwood to cut around.
- 10% or less for sheet goods and dimensional lumber cut to standard lengths.
Questions
What is a board foot?
A board foot is a volume of wood: one foot long, one foot wide and one inch thick, or 144 cubic inches. Hardwood lumber is sold and priced by the board foot.
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A board 1 inch thick, 6 inches wide and 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet. With the length in inches, divide by 144 instead.
How many board feet are in a 2x4x8?
5.33 board feet, using the nominal size: 2 × 4 × 8 ÷ 12. Construction lumber is priced on its nominal size even though a 2x4 actually measures 1.5 by 3.5 inches.
What is the difference between board feet and linear feet?
Linear feet measure only length, whatever the board's size. Board feet measure volume. A 1x6 that is 8 feet long is 8 linear feet but 4 board feet.
What do 4/4, 5/4 and 8/4 mean?
Hardwood thickness in quarters of an inch, measured rough: 4/4 is 1 inch, 5/4 is 1¼ inches, 8/4 is 2 inches. Board feet are calculated on that rough thickness, before planing.
How much extra wood should I buy?
Add about 15 to 20% for offcuts, defects and mistakes on a typical hardwood project, and more (25 to 35%) for figured wood or boards with a lot of knots and checks.
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