How to calculate board feet
A board foot is a volume: 144 cubic inches, the same as a board 1 inch thick, 12 inches wide and 1 foot long. Three versions of the formula give the same answer:
- Board feet = thickness (in) × width (in) × length (ft) ÷ 12
- Board feet = thickness (in) × width (in) × length (in) ÷ 144
- Board feet = linear feet × thickness (in) × width (in) ÷ 12
The calculator works out each line of your list, multiplies it by the quantity and adds the lines up. The waste allowance goes on top of that total, and the price is applied to the total with waste, because that is what you have to buy. In metric mode it reports cubic meters: one board foot is 0.002359737 m³, so a cubic meter is about 423.8 board feet.
Hardwood quarters vs softwood nominal sizes
The thickness you type decides the answer, and the lumber trade uses two conventions.
Hardwood is sawn and sold in quarters of an inch. A 4/4 board is 1 inch thick rough-sawn, and that is the thickness the board feet are figured on, even when the yard has planed both faces (S2S) for you. Width and length are measured on the actual board. Hardwood usually comes in random widths, and yards often round each board's tally, so their total can differ a little from yours.
| Quarter size | Rough thickness (used for board feet) | Typical S2S thickness |
|---|---|---|
| 4/4 | 1 in (25.4 mm) | 13⁄16 in |
| 5/4 | 1 ¼ in (31.8 mm) | 1 1⁄16 in |
| 6/4 | 1 ½ in (38.1 mm) | 1 5⁄16 in |
| 8/4 | 2 in (50.8 mm) | 1 ¾ in |
| 10/4 | 2 ½ in (63.5 mm) | 2 ¼ in |
| 12/4 | 3 in (76.2 mm) | 2 ¾ in |
Mills differ in how much they plane off, so measure before you design around a surfaced thickness.
Softwood dimension lumber is named by its nominal size. A 2×4 is really 1 ½ × 3 ½ inches once dried and planed, but yards that sell softwood by the board foot count it as 2 × 4. Enter the nominal size to check a quote, or the actual size for the wood you really get. Home centers mostly sell dimension lumber by the piece, so this matters most at lumberyards and for comparing prices.
Board feet chart for common boards
Hardwood, figured on rough thickness:
| Board | Calculation | Board feet |
|---|---|---|
| 4/4 × 4 in × 8 ft | 1 × 4 × 8 ÷ 12 | 2.67 |
| 4/4 × 6 in × 8 ft | 1 × 6 × 8 ÷ 12 | 4 |
| 4/4 × 8 in × 8 ft | 1 × 8 × 8 ÷ 12 | 5.33 |
| 4/4 × 6 in × 10 ft | 1 × 6 × 10 ÷ 12 | 5 |
| 5/4 × 6 in × 8 ft | 1.25 × 6 × 8 ÷ 12 | 5 |
| 6/4 × 6 in × 8 ft | 1.5 × 6 × 8 ÷ 12 | 6 |
| 8/4 × 6 in × 8 ft | 2 × 6 × 8 ÷ 12 | 8 |
| 8/4 × 8 in × 10 ft | 2 × 8 × 10 ÷ 12 | 13.33 |
| 12/4 × 6 in × 8 ft | 3 × 6 × 8 ÷ 12 | 12 |
Softwood, nominal and actual:
| Board | Board feet (nominal) | Actual size | Board feet (actual) |
|---|---|---|---|
| 1×4×8 | 2.67 | ¾ × 3 ½ in | 1.75 |
| 1×6×8 | 4 | ¾ × 5 ½ in | 2.75 |
| 2×4×8 | 5.33 | 1 ½ × 3 ½ in | 3.5 |
| 2×4×10 | 6.67 | 1 ½ × 3 ½ in | 4.38 |
| 2×6×8 | 8 | 1 ½ × 5 ½ in | 5.5 |
| 2×6×10 | 10 | 1 ½ × 5 ½ in | 6.88 |
| 2×8×12 | 16 | 1 ½ × 7 ¼ in | 10.88 |
| 2×10×12 | 20 | 1 ½ × 9 ¼ in | 13.88 |
| 2×12×16 | 32 | 1 ½ × 11 ¼ in | 22.5 |
| 4×4×8 | 10.67 | 3 ½ × 3 ½ in | 8.17 |
| 6×6×8 | 24 | 5 ½ × 5 ½ in | 20.17 |
Board feet and linear feet
Trim, moulding and some dimension lumber are priced by the linear (running) foot. For one cross-section, every linear foot holds thickness × width ÷ 12 board feet, so converting is one multiplication.
| Cross-section (nominal) | Board feet per linear foot | Linear feet per 100 board feet |
|---|---|---|
| 1×4 or 4/4 × 4 in | 0.333 | 300 |
| 1×6 or 4/4 × 6 in | 0.5 | 200 |
| 1×8 or 4/4 × 8 in | 0.667 | 150 |
| 1×12 or 4/4 × 12 in | 1 | 100 |
| 2×4 or 8/4 × 4 in | 0.667 | 150 |
| 2×6 or 8/4 × 6 in | 1 | 100 |
| 2×8 | 1.333 | 75 |
| 2×10 | 1.667 | 60 |
| 2×12 | 2 | 50 |
| 4×4 | 1.333 | 75 |
| 6×6 | 3 | 33.3 |
Example: pricing a hardwood cut list
A cabinet needs six 4/4 boards 6 in × 8 ft, two 8/4 boards 8 in × 10 ft and four 5/4 boards 5 in × 6 ft.
- 4/4: 1 × 6 × 8 ÷ 12 = 4 board feet each, × 6 = 24 board feet.
- 8/4: 2 × 8 × 10 ÷ 12 = 13.33 each, × 2 = 26.67 board feet.
- 5/4: 1.25 × 5 × 6 ÷ 12 = 3.125 each, × 4 = 12.5 board feet.
- Total: 24 + 26.67 + 12.5 = 63.17 board feet.
- With 20 percent waste: 63.17 × 1.2 = 75.8 board feet to buy.
- At $9.50 a board foot: 75.8 × 9.50 = $720.10.
That price is only an example; hardwood prices vary widely with species, grade and region.
Tips for buying lumber by the board foot
- Buy thick enough to mill flat. 4/4 rough stock is the usual starting point for ¾-inch parts. For parts a full inch thick, start with 5/4.
- Keep one line per thickness. Yards stack and price 4/4, 5/4 and 8/4 separately, so a list split by thickness is easier to shop.
- Allow for the ends. Rough boards often have checks at the ends that you cut off, so add a few inches to each part's length.
- Grade changes the waste. Lower grades such as No. 1 Common cost less per board foot but give shorter clear pieces, so raise the waste allowance.
- Check the tally. Ask for the yard's tally and compare it with yours; rounding and measured widths explain small differences.
Frequently asked questions
How do you calculate board feet?
Multiply the thickness in inches by the width in inches by the 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. If you measure the length in inches, divide by 144 instead.
How many board feet are in a 2×4×8?
5.33 board feet on its nominal size (2 × 4 × 8 ÷ 12), which is how lumberyards count softwood. On its actual size of 1 ½ × 3 ½ inches it holds 3.5 board feet of wood.
What does 4/4 mean in lumber?
Hardwood thickness is given in quarters of an inch, so 4/4 ("four quarter") is 1 inch thick rough-sawn, 5/4 is 1 ¼ inches and 8/4 is 2 inches. Board feet are figured on that rough thickness, even after the board has been planed to about 13/16 inch.
How do you convert linear feet to board feet?
Multiply the linear feet by the thickness and width in inches and divide by 12. Fifty linear feet of 4/4 × 6 inch stock is 50 × 1 × 6 ÷ 12 = 25 board feet. To go the other way, divide the board feet by thickness × width ÷ 12.
How much extra lumber should I buy for waste?
Many woodworkers add 15 to 30 percent to the board feet in their cut list. Use the low end for clear, surfaced stock and simple parts, and the high end for rough lumber, lower grades with knots and checks to cut around, or projects with many small parts or matched grain.
How many board feet are in a cubic meter?
About 423.8. One board foot is 144 cubic inches, which is 0.002359737 cubic meters.
Last updated October 17, 2026.