Board Foot Calculator
A board foot is 144 cubic inches of wood: 1 inch thick, 12 inches wide and 1 foot long. Multiply thickness (in) × width (in) × length (ft) and divide by 12: a 4/4 board 6 inches wide and 8 feet long is 4 board feet, and an 8 ft 2×4 is ≈ 5.33. Use nominal sizes, not measured ones: a 2×4 counts as 2 × 4 and 4/4 hardwood as 1 inch thick. The example cut list below comes to ≈ 42.67 BF, or ≈ 49.07 BF with 15% waste, which is $368.00 at $7.50 a board foot.
Updated Runs in your browser: nothing you enter is uploadedHow this tool works
≈ 49.07 board feet to buy
- Board feet (6 boards)
- ≈ 42.67 BF
- Waste allowance (15%)
- + 6.4 BF
- Board feet to buy
- ≈ 49.07 BF
- Volume (before waste)
- ≈ 3.5556 cu ft · ≈ 0.1007 m³
- Cost at $7.50 per board foot
- $368.00
Hardwood thickness in quarters
| Quarters | Rough thickness (billed) | Surfaced two sides (S2S) | Board feet in a 6 in × 8 ft board |
|---|---|---|---|
| 4/4 | 1" | 13/16" | 4 |
| 5/4 | 1 1/4" | 1 1/16" | 5 |
| 6/4 | 1 1/2" | 1 5/16" | 6 |
| 8/4 | 2" | 1 3/4" | 8 |
| 10/4 | 2 1/2" | 2 1/4" | 10 |
| 12/4 | 3" | 2 3/4" | 12 |
| 16/4 | 4" | 3 3/4" | 16 |
Board feet of common softwood lumber
| Nominal size | Actual size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|---|
| 1×4 | 3/4″ × 3 1/2″ | ≈ 2.67 | ≈ 3.33 | 4 | ≈ 5.33 |
| 1×6 | 3/4″ × 5 1/2″ | 4 | 5 | 6 | 8 |
| 1×8 | 3/4″ × 7 1/4″ | ≈ 5.33 | ≈ 6.67 | 8 | ≈ 10.67 |
| 1×12 | 3/4″ × 11 1/4″ | 8 | 10 | 12 | 16 |
| 2×4 | 1 1/2″ × 3 1/2″ | ≈ 5.33 | ≈ 6.67 | 8 | ≈ 10.67 |
| 2×6 | 1 1/2″ × 5 1/2″ | 8 | 10 | 12 | 16 |
| 2×8 | 1 1/2″ × 7 1/4″ | ≈ 10.67 | ≈ 13.33 | 16 | ≈ 21.33 |
| 2×10 | 1 1/2″ × 9 1/4″ | ≈ 13.33 | ≈ 16.67 | 20 | ≈ 26.67 |
| 2×12 | 1 1/2″ × 11 1/4″ | 16 | 20 | 24 | 32 |
| 4×4 | 3 1/2″ × 3 1/2″ | ≈ 10.67 | ≈ 13.33 | 16 | ≈ 21.33 |
| 6×6 | 5 1/2″ × 5 1/2″ | 24 | 30 | 36 | 48 |
How to calculate board feet
- Take the nominal size. Use the thickness and width the lumber is sold as: 2×6 is 2 by 6 inches, 8/4 hardwood is 2 inches thick. Width is in inches, length in feet.
- Multiply and divide by 12. Thickness × width × length ÷ 12 gives board feet per piece: 2 × 6 × 10 ÷ 12 = 10 for a 10 ft 2×6. With the length in inches, divide by 144 instead.
- Multiply by the number of pieces. Four of those boards are 4 × 10 = 40 board feet.
- Add up the list and allow for waste. Add every row, then add a waste allowance for defects, planing and offcuts: 15 to 20% is common for rough hardwood, more for figured or low-grade stock.
- Price it. Multiply the board feet to buy by the price per board foot to get the cost.
Frequently asked questions
- What is a board foot?
- A unit of volume for lumber: 144 cubic inches, the same as a board 1 inch thick, 12 inches wide and 1 foot long (or 1 × 6 × 24 inches, or 2 × 6 × 12). Twelve board feet make a cubic foot. Lumberyards price hardwood and many softwoods per board foot, or per thousand board feet (MBF).
- Do I use nominal or actual dimensions for board feet?
- Nominal. Board feet are tallied on the size the lumber is sold as, so an 8 ft 2×4 is 2 × 4 × 8 ÷ 12 = ≈ 5.33 board feet even though it measures 1 1/2 × 3 1/2 inches. For rough hardwood, the thickness is its quarter size (4/4 is 1 inch) and the width is what the board measures, since hardwood comes in random widths. Surfacing does not change the count: 4/4 planed to 13/16 inch is still billed as 1 inch thick.
- What do 4/4, 5/4 and 8/4 mean?
- The rough thickness of hardwood in quarters of an inch, said "four quarter", "five quarter", "eight quarter": 4/4 is 1 inch, 5/4 is 1 1/4, 6/4 is 1 1/2, 8/4 is 2 inches. Planed on both faces (S2S), 4/4 comes to about 13/16 inch and 8/4 to about 1 3/4. Quarters have nothing to do with quartersawn lumber, which is a way of cutting the log. Type 5/4 or 1.25 into the thickness field; both are read as 1 1/4 inches.
- Why is my lumberyard’s tally different?
- Hardwood dealers following the National Hardwood Lumber Association rules measure each board and round as they go: widths to the nearest inch, lengths down to the whole foot, and each board’s surface measure (width × length ÷ 12) to the nearest whole number, which is then multiplied by the thickness. Stock 4/4 and thinner counts as a full inch. This calculator works the exact figure for the sizes you type, so a yard’s tally of the same boards can differ by a little either way.
- How much waste should I add?
- For furniture and cabinet parts cut from rough hardwood, 15 to 20% covers knots, checks, snipe and offcuts; allow 30% or more for figured wood, low grades or many short parts. For framing lumber bought to length, 5 to 10% is usually enough. The example uses 15%: ≈ 42.67 BF becomes ≈ 49.07 BF.
- Is hardwood flooring sold by the board foot?
- No. Flooring is sold by the square foot of floor it covers, so use a flooring calculator for it. Board feet are for lumber: rough or surfaced boards, dimension lumber, slabs and turning blanks.
- What is the difference between board feet and linear feet?
- Linear feet only measure length. Board feet measure volume, so a board's width and thickness count too: 10 linear feet of 1×6 is 5 board feet, while 10 linear feet of 2×12 is 20. Trim, decking and dimension lumber at home centers are often priced per piece or per linear foot instead.
How it works
Each row's board feet are pieces × thickness × width × length ÷ 144, with every size in inches. Sizes are read by the same parser as the feet and inches calculator, so quarters (5/4), fractions (1 1/2), decimals and units (96", 8', 2.4 m) all work; a length with no unit is read in feet or inches as you choose, and thickness and width in inches. The arithmetic is exact (fractions of whole numbers), and only the display is rounded, to two decimals, marked ≈ when rounded. The waste allowance multiplies the total by 1 + waste ÷ 100, and the cost is the board feet to buy times your price, rounded to the cent. Volume is total board feet ÷ 12 in cubic feet, and × 0.002359737216 in cubic meters (144 cubic inches exactly). The figures are for the sizes you enter; the tool does not apply a dealer's per-board rounding. Everything runs in your browser.
Sources
- American Hardwood Export Council: grading sawn lumber, measurement (surface measure, quarters, rounding)
- National Hardwood Lumber Association, Rules for the Measurement and Inspection of Hardwood and Cypress
- American Softwood Lumber Standard, Voluntary Product Standard PS 20 (nominal and dressed sizes), NIST
- Wood Handbook: Wood as an Engineering Material (FPL-GTR-282, 2021), chapter 6, Commercial Lumber, USDA Forest Products Laboratory
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