Lumber & Hardwood Math
Board Foot Calculator
A free lumber board foot calculator for woodworkers and carpenters. Estimate board feet and cost in seconds — add multiple boards, pick presets like 2×4 or 4/4, add a waste factor, and get an instant total.
Calculator
Calculate Board Feet
This board foot calculator turns each board's thickness, width, and length into board feet, linear feet, and cost. It handles a mix of sizes in one order — the same tool people mean when they search for a bd ft calculator. Add a price per board foot to price the whole order.
Use a preset to fill the selected row. If no row is selected, it adds a new board.
Boards
Extra material to buy. 0% = exact.
Optional. With a price filled in, this is a price per board foot calculator for the whole order.
The math
What is a board foot?
A board foot is a unit of volume used to price hardwood and softwood lumber. It equals a board 12 inches long, 12 inches wide, and 1 inch thick — 144 cubic inches. Because hardwood is rarely sold in neat 1×12 flats, board feet let buyers and sellers compare different board sizes by volume instead of by length. The board feet calculator on this page uses that same board footage math. Here is how to calculate board feet for any board, in three steps.
Formula
BF = L(ft) × W(in) × T(in) ÷ 12
For a full pack: BF = L(ft) × W(in) × T(in) × quantity ÷ 12
In metric terms, one board foot is about2.36 liters or0.00236 m³. If you work in millimeters, convert to inches first: divide mm by 25.4.
- 01
Measure in inches and feet
Thickness and width are entered in inches. Length is entered in feet (switch to inches if your cut list uses them).
- 02
Multiply and divide by 12
Board feet = length (ft) × width (in) × thickness (in) ÷ 12. One board foot is 1 ft × 1 ft × 1 in.
- 03
Add every board
Multiply a single board by its quantity, then sum all rows. Add a waste factor before you buy.
Worked examples
Here is how to figure board feet by hand for a few common boards, using the same formula as a lumber board foot calculator.
A single walnut board
1 in × 10 in × 8 ft
8 × 10 × 1 ÷ 12
6.67 bf
Five 5/4 boards
1.25 in × 6 in × 12 ft × 5
12 × 6 × 1.25 × 5 ÷ 12
37.5 bf
A 2×4 stud
2 in × 4 in × 8 ft (nominal)
8 × 4 × 2 ÷ 12
5.33 bf
Reference
Board feet by common lumber size
Dimensional lumber is named by its rough (nominal) size, but sells at a smaller dressed size. Board footage is usually figured on the nominal size for softwoods, and on the rough thickness in quarters — such as 4/4 (1 in) — for hardwood. Pick a size in the board ft calculator above, or use the table as a quick lookup — same volume math as a board footage calculator.
| Nominal | Actual (in) | BF / ft | BF / 8 ft | BF / 12 ft |
|---|---|---|---|---|
| 1×4 | 3/4 × 3 1/2" | 0.33 | 2.67 | 4 |
| 1×6 | 3/4 × 5 1/2" | 0.5 | 4 | 6 |
| 1×8 | 3/4 × 7 1/4" | 0.67 | 5.33 | 8 |
| 1×10 | 3/4 × 9 1/4" | 0.83 | 6.67 | 10 |
| 1×12 | 3/4 × 11 1/4" | 1 | 8 | 12 |
| 2×4 | 1 1/2 × 3 1/2" | 0.67 | 5.33 | 8 |
| 2×6 | 1 1/2 × 5 1/2" | 1 | 8 | 12 |
| 2×8 | 1 1/2 × 7 1/4" | 1.33 | 10.67 | 16 |
| 2×10 | 1 1/2 × 9 1/4" | 1.67 | 13.33 | 20 |
| 2×12 | 1 1/2 × 11 1/4" | 2 | 16 | 24 |
| 4×4 | 3 1/2 × 3 1/2" | 1.33 | 10.67 | 16 |
| 6×6 | 5 1/2 × 5 1/2" | 3 | 24 | 36 |
Values use nominal dimensions. Hardwood is typically measured and billed on its rough thickness in quarters (4/4 = 1 in), not the surfaced thickness.
FAQ
Board foot questions, answered
What is a board foot calculator?
A board foot calculator is a tool that converts a board's thickness, width, and length into board feet — the volume unit lumber yards use to price hardwood and many mill-run boards. Enter each board, or a whole cut list, and it totals the board feet. Add a waste percentage and a price per board foot to see how much to buy and what the order costs.
How does a board foot calculator work?
It applies the standard formula: board feet = length (ft) × width (in) × thickness (in) ÷ 12, then multiplies by the quantity. This calculator also sums mixed sizes in one list, converts a length entered in inches to feet, and can add waste and a price per board foot so the result is buy quantity and cost, not just volume.
How do you figure board feet with a calculator?
Enter thickness and width in inches, length in feet or inches, and how many pieces. The calculator returns board feet for that row and a running total. Add more rows for mixed sizes, then optionally set waste and price to get the amount to buy and the total cost.
How do you calculate board feet?
Use the formula: board feet = length (ft) × width (in) × thickness (in) ÷ 12. Length is measured in feet, while width and thickness are measured in inches. Multiply by the number of boards to get the total.
How many board feet are in a 2×4?
Board feet = length (ft) × 2 × 4 ÷ 12. An 8 ft 2×4 is about 5.33 board feet using nominal dimensions. If you use the actual dressed size (1½ × 3½ in), it comes to about 3.5 board feet.
What is the difference between a board foot and a linear foot?
A board foot measures volume — 1 ft × 1 ft × 1 in, or 144 cubic inches. A linear foot measures length only, regardless of width or thickness. Lumber priced by volume uses board feet; trim and moulding are often priced by the linear foot.
Should I use nominal or actual dimensions?
Softwood lumber priced by volume is normally figured on nominal size, e.g. a 2×4. Framing studs are often sold per piece instead, so check how your yard prices them. Hardwood is typically figured on its rough thickness in quarters, such as 4/4 (1 in) or 5/4 (1¼ in).
How much waste should I add?
For simple cuts, 5–10% is common. For projects with many angled or fitted cuts, plan on 15–20%. The calculator's waste field is applied on top of the exact board feet so you know how much to buy.