Hardwood dealers, sawmills and many lumberyards sell wood by the board foot, a measure of volume rather than length. That makes a 2-inch-thick walnut slab and a stack of thin boards comparable on price, but it also means you need a quick way to turn dimensions into board feet. This calculator does that for any number of identical boards and multiplies by your price per board foot.
How to use the board foot calculator
- Enter the thickness and width in inches. Use the nominal or rough size — 1 inch for 4/4 stock, 2 inches for 8/4.
- Enter the length in feet, inches or meters.
- Enter the number of boards of that size.
- Optionally enter the price per board foot and an extra percentage for defects and cutting waste.
- Read the total board feet, cost and equivalent cubic volume.
Board foot formula
If the length is in inches, divide by 144 instead. The 12 and the 144 come from the definition: one board foot is 1 × 12 × 12 inches.
Worked examples
Twelve 1 × 8 boards, 10 ft long: 1 × 8 × 10 ÷ 12 = 6.667 BF each; × 12 = 80 BF. At $6.50 per board foot, the order costs $520, or $43.33 per board.
One 2 × 6 × 12 ft: 2 × 6 × 12 ÷ 12 = 12 BF.
An 8/4 walnut board 7 in wide and 8 ft long: 2 × 7 × 8 ÷ 12 = 9.33 BF.
Nominal size versus actual size
Softwood construction lumber is named by its rough-sawn size before drying and planing. A “2 × 4” is actually about 1½ × 3½ inches, and a “1 × 8” about ¾ × 7¼ inches. Board feet are traditionally counted on those nominal numbers, which is why a 2×4×8 is 5.33 BF even though its actual volume is smaller.
Hardwoods follow the quarter system. Boards are sold by rough thickness in quarters of an inch and often in random widths and lengths, so each board is measured and tallied individually.
| Quarter designation | Rough thickness | Typical surfaced (S2S) thickness |
|---|---|---|
| 4/4 | 1 in | about 13/16 in |
| 5/4 | 1¼ in | about 1 1/16 in |
| 6/4 | 1½ in | about 1 5/16 in |
| 8/4 | 2 in | about 1 3/4 in |
| 12/4 | 3 in | about 2 3/4 in |
Surfaced sizes vary by mill; ask your supplier how they tally boards they have already planed.
Buying tips
- Add extra for defects. Rough hardwood includes knots, checks, wane and sapwood you will cut away. Woodworkers commonly add 15–30% depending on the grade and how much clear stock the project needs.
- Compare prices by the board foot. A wide board at a higher price per piece may be cheaper per board foot than narrow boards.
- Check whether the price is per BF or per linear foot. Dimensional lumber at home centers is usually priced per piece; the table under the result converts common sizes to board feet per linear foot so you can compare.
- Think in volume for heavy stock. Twelve board feet equal one cubic foot, which helps estimate weight: many hardwoods weigh roughly 35–50 pounds per cubic foot when dry.
To total up mixed lengths from a cut list, the feet and inches calculator handles fractional measurements.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide and 12 inches long — 144 cubic inches. Twelve board feet make one cubic foot.
How many board feet are in a 2×4×8?
Using nominal dimensions, 2 × 4 × 8 ÷ 12 = 5.33 board feet. A 2×6×12 is 12 board feet and a 1×12×8 is 8 board feet.
Should I use nominal or actual dimensions?
Lumber is traditionally tallied on nominal or rough-sawn sizes, not the smaller dressed size. A 2×4 measures about 1½ × 3½ inches but is counted as 2 × 4. Hardwood sold surfaced is still usually priced on its rough thickness, such as 4/4.
What does 4/4 or 8/4 mean?
Hardwood thickness is described in quarters of an inch. 4/4 (four-quarter) is 1 inch rough, 5/4 is 1¼ inches, 6/4 is 1½ inches and 8/4 is 2 inches. Enter the quarter thickness as inches in the calculator.
What is MBF?
MBF means one thousand board feet, the unit sawmills and wholesalers often use for pricing. A price of $2,400 per MBF is $2.40 per board foot.