How to use the board foot calculator
- Enter the thickness of the board in inches.
- Enter the width in inches and the length in feet.
- Set the number of pieces if you have more than one identical board.
- Read the calculated board feet per piece and the total board feet instantly.
How board feet are calculated
A board foot is defined as a volume of wood measuring one inch thick, twelve inches wide and twelve inches long, which equals 144 cubic inches. The formula used by any lumber calculator is straightforward:
Board Feet = (Thickness × Width × Length) / 12
In this formula, thickness and width are measured in inches while length is measured in feet. Because one foot equals twelve inches, multiplying thickness (inches) by width (inches) by length (feet) gives a result in square-inch-feet. Dividing by 12 converts that product into board feet, since one board foot is 144 cubic inches and one inch-foot is 12 cubic inches.
For example, a board that is 2 inches thick, 6 inches wide and 8 feet long yields: (2 × 6 × 8) / 12 = 96 / 12 = 8 board feet. If you need ten of those boards, multiply by ten to get 80 total board feet.
Common lumber sizes in board feet
The table below shows the board foot volume for several standard lumber dimensions at a length of eight feet. These values assume actual dimensions rather than nominal sizing.
| Thickness (in) | Width (in) | Length (ft) | Board Feet |
|---|---|---|---|
| 1 | 4 | 8 | 2.667 |
| 1 | 6 | 8 | 4 |
| 1 | 8 | 8 | 5.333 |
| 1 | 10 | 8 | 6.667 |
| 1 | 12 | 8 | 8 |
| 2 | 6 | 8 | 8 |
| 2 | 8 | 8 | 10.667 |
| 2 | 10 | 8 | 13.333 |
| 2 | 12 | 8 | 16 |
Keep in mind that nominal lumber sizes differ from actual sizes. A nominal 2x4 actually measures 1.5 inches by 3.5 inches. When pricing hardwood, mills typically use the actual rough-sawn dimensions, so always measure your stock before running the numbers through a lumber calculator.
Why board feet matter for buying lumber
Hardwood lumber in North America is almost exclusively sold by the board foot rather than by linear foot or by the piece. This system accounts for variations in both thickness and width, ensuring that buyers pay for the actual volume of wood they receive. Softwood construction lumber, such as framing studs, is usually sold by the piece, but specialty softwoods and clear grades may also be priced per board foot.
When you visit a sawmill or hardwood dealer, knowing how to calculate board feet helps you verify quotes and compare prices between suppliers. A board that costs $8 per board foot will cost exactly twice as much as the same species at $4 per board foot, regardless of the individual dimensions of each plank.
Woodworkers planning a project often estimate the total board feet needed, add a waste factor of ten to twenty percent for defects and offcuts, and then use that figure to budget for materials. Using a lumber calculator before shopping prevents overbuying and keeps project costs predictable.
Nominal versus actual dimensions
One of the most common mistakes when calculating board feet is using nominal dimensions instead of actual measurements. In the softwood industry, a "2x4" refers to the size of the board before it is dried and planed. The finished board actually measures about 1.5 inches thick and 3.5 inches wide.
Hardwood is typically sold in quarter increments for thickness. A board listed as 4/4 (pronounced "four-quarter") is roughly one inch thick in the rough, or about 13/16 inch after surfacing on two sides. An 8/4 board is approximately two inches thick rough. When you use this lumber calculator, enter the actual thickness you are working with to get an accurate volume.
If a supplier quotes you based on nominal sizes but delivers surfaced lumber, the actual board footage may be slightly less than expected. Always clarify whether the price applies to rough or surfaced dimensions.
Converting board feet to other units
Sometimes you need to convert board feet into cubic inches, cubic feet or even metric units. Here are the key conversion factors:
- 1 board foot = 144 cubic inches
- 1 board foot = 1/12 cubic foot (approximately 0.0833 cubic feet)
- 1 board foot = 2,359.74 cubic centimeters (about 2.36 liters)
- 1 cubic meter = 423.776 board feet
To convert a total board foot measurement to cubic feet, simply divide by 12. For example, 24 board feet equals 2 cubic feet. To convert to cubic meters, divide the board feet by 423.776. These conversions are useful when comparing domestic hardwood prices to imported timber sold by the cubic meter.
Worked examples
Each result below was produced by the same code the tool runs, so you can check your own numbers against them.
| Example | Input | Result |
|---|---|---|
| Standard 1x6x8 board | Thickness (inches): 1; Width (inches): 6; Length (feet): 8; Number of pieces: 1 | Board feet per piece: 4; Total board feet: 4; Total cubic inches: 576; Total cubic feet: 0.333333 |
| Thick slab 2x12x10 | Thickness (inches): 2; Width (inches): 12; Length (feet): 10; Number of pieces: 1 | Board feet per piece: 20; Total board feet: 20; Total cubic inches: 2,880; Total cubic feet: 1.66667 |
| Ten 1x4x6 boards | Thickness (inches): 1; Width (inches): 4; Length (feet): 6; Number of pieces: 10 | Board feet per piece: 2; Total board feet: 20; Total cubic inches: 2,880; Total cubic feet: 1.66667 |
| Quarter-sawn 5/4 x 8 x 12 | Thickness (inches): 1.25; Width (inches): 8; Length (feet): 12; Number of pieces: 1 | Board feet per piece: 10; Total board feet: 10; Total cubic inches: 1,440; Total cubic feet: 0.833333 |
FAQ
What exactly is a board foot?
A board foot is a unit of volume used for lumber. It represents a piece of wood that is one inch thick, twelve inches wide and twelve inches long, totaling 144 cubic inches.
Do I use nominal or actual dimensions in this lumber calculator?
You should use the actual dimensions of the wood you are measuring. Nominal sizes like 2x4 refer to the rough green size, not the finished dimensions. Hardwood dealers typically measure actual thickness in quarter increments.
How do I calculate board feet for a log?
Logs are estimated using scaling rules such as Doyle, Scribner or International 1/4-inch. These formulas account for bark, saw kerf and taper. This board foot calculator is designed for sawn lumber, not round logs.
Is a board foot the same as a square foot?
No. A square foot measures area (length times width), while a board foot measures volume (length times width times thickness). A board that is one inch thick and one square foot in area equals exactly one board foot.
Why is hardwood sold by the board foot instead of by the piece?
Hardwood boards vary widely in width and thickness. Selling by the board foot ensures that customers pay for the actual volume of wood they receive, making pricing fair regardless of the specific dimensions of each plank.
Does this tool store my measurements or send them anywhere?
No. This lumber calculator runs entirely in your browser. Your inputs are never uploaded to a server, so your project details remain private.