Board Foot Calculator
1 board foot = 144 in³ = 1/12 ft³. Formula: BF = (L × W × T) / 144 (all dimensions in inches).
- Board foot definition: 1 BF = 144 in³ = 1/12 ft³.
- Formula: BF = (Length × Width × Thickness) / 144 when all dimensions are in inches.
- Mixed ft/in and m/cm inputs are converted to inches first, then used in the standard formula.
A board foot calculator converts a stack of boards into a consistent lumber-volume measurement. Enter the actual or nominal thickness, width, length, and number of pieces above to estimate total board feet, compare prices between sizes, or plan how much stock a project may require.
What Is a Board Foot?
One board foot represents a volume of 144 cubic inches: a board 1 inch thick, 12 inches wide, and 12 inches long. The board does not need to have those exact dimensions. A 2-inch-thick board that is 6 inches wide and 12 inches long also contains one board foot.
Lumberyards commonly use board feet for hardwoods and rough-sawn stock because it makes different thicknesses and widths comparable. Linear feet describe length only, while square feet describe surface area. Board feet include thickness, so they answer a different question.
Board Foot Formula
When thickness and width are in inches and length is in feet, use:
Board feet = thickness (in) × width (in) × length (ft) × quantity ÷ 12
For a single 2 × 8 board that is 10 feet long, the calculation is 2 × 8 × 10 ÷ 12 = 13.33 board feet. Multiply by the number of identical pieces to find the batch total.
How to Use the Lumber Calculator
- Select the measurement units shown in the calculator.
- Enter thickness, width, and length for one board.
- Enter the number of matching boards.
- Review the board-foot result and round up for cuts, defects, and selection.
If a purchase list contains several sizes, calculate each line separately and add the results. This avoids averaging widths or thicknesses that should be priced independently.
Nominal Size Versus Actual Size
A label such as “2 × 4” may describe a nominal construction-lumber size rather than the board’s finished dimensions. Surfacing and drying reduce actual thickness and width. Hardwood may also be sold by quarter thickness—such as 4/4 or 8/4—before final milling.
Use the dimensions on the supplier’s price basis. If the yard calculates rough lumber from nominal or measured rough dimensions, match that convention. For finished project volume, enter the dimensions the part will actually have.
Board Feet to Square Feet
Board feet cannot be converted to square feet unless thickness is known. For stock measured in inches:
Square feet = board feet ÷ thickness (inches)
For example, 20 board feet of 1-inch material covers 20 square feet. The same 20 board feet of 2-inch material covers only 10 square feet. For area-only jobs, try the square footage calculator.
Estimating Lumber Cost
Multiply total board feet by the supplier’s price per board foot. If 32.5 board feet costs $8.40 per board foot, the base material estimate is $273. Add taxes, delivery, milling charges, and a waste allowance separately so the result remains easy to audit.
When a store prices boards individually or by linear foot, do not apply a board-foot price unless you first convert the store’s basis correctly. The cheapest price per board may not be the lowest price for an equal volume.
How Much Extra Lumber Should You Buy?
There is no universal waste percentage. Straight-grained furniture parts, wide color matching, knots, checks, and complicated cutting layouts may require more selection than simple blocking. Build the cut list first, calculate its theoretical volume, then add a project-specific allowance. Buying a little extra from the same batch can also reduce color and grain mismatch later.
Common Measurement Mistakes
- Entering feet in a field that expects inches.
- Using nominal dimensions when the price uses actual dimensions, or the reverse.
- Forgetting to multiply by quantity.
- Treating board feet as a length or surface-area measurement.
- Rounding every board before adding the full order.
Keep full precision through the calculation and round the final buying quantity. For background on industry conversion factors, consult the US Forest Products Laboratory reference.
Board Foot Calculator FAQs
How many board feet are in a 2 × 4 × 8?
Using the nominal dimensions, 2 × 4 × 8 ÷ 12 equals 5.33 board feet. If you need finished volume, enter the board’s actual measured thickness and width instead.
Is a board foot the same as a linear foot?
No. A linear foot measures only length. A board foot measures volume and changes with thickness and width.
Can plywood be measured in board feet?
It can be converted as a volume, but plywood is usually sold by sheet or square foot. Use the unit that matches the supplier’s quote and your purchasing decision.