Board Foot Calculator
Enter the thickness, width and length of a board and how many you have to see the board feet of lumber. Add a price per board foot to estimate the cost.
How to use this board foot calculator
- Enter the thickness and width of the board in inches. Use the size you are billed for.
- Enter the length and choose feet or inches.
- Enter how many boards you have or need.
- Add a price per board foot if you want a cost estimate.
- Press Calculate. Use Copy result or Export CSV to keep the numbers for an order or a quote.
How to calculate board feet
A board foot is a unit of lumber volume. One board foot is 144 cubic inches, which is a piece 1 inch thick, 12 inches wide and 12 inches long.
- Board feet per board = thickness (in) x width (in) x length (ft) / 12
- Total board feet = board feet per board x number of boards
- Cost = total board feet x price per board foot
If the length is in inches, the formula becomes thickness x width x length / 144.
Worked example
You need 10 boards that are 2 inches thick, 6 inches wide and 8 feet long. One board is 2 x 6 x 8 / 12 = 8 board feet. Ten boards are 80 board feet. At $4.25 per board foot the lumber costs 80 x 4.25 = $340.00.
The same 10 boards are 80 linear feet in total and 6.67 cubic feet of wood.
Assumptions & limits
- Board feet are calculated from the thickness and width you enter. Nominal sizes, such as a 2 by 6 that measures 1.5 by 5.5 inches, are billed differently by different suppliers, so ask how your supplier measures.
- The calculation treats each board as a solid rectangle with no waste.
- The price per board foot is your own input. The calculator does not look up prices.
- Board feet are a volume measure and are not the same as linear feet or square feet.
- Rough, dried and planed lumber can be priced differently, so use the unit that your supplier quotes.
Frequently asked questions
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet and divide by 12. A 2 inch by 6 inch board that is 8 feet long is 8 board feet.
What is a board foot?
A board foot is a volume of lumber equal to 144 cubic inches, which is a piece 1 inch thick, 12 inches wide and 12 inches long.
Is a board foot the same as a linear foot?
No. A linear foot measures length only. A board foot includes thickness and width, so it measures volume.
Do I use nominal or actual sizes?
It depends on how your supplier bills. Hardwood is often sold by rough thickness, and softwood by nominal size. Ask your supplier which size they use for pricing.
How do I calculate board feet with inches for length?
Multiply thickness, width and length in inches, then divide by 144. The calculator does this when you choose inches.
How do I convert board feet to cubic feet?
Divide board feet by 12. 80 board feet is about 6.67 cubic feet.
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Last updated: November 2026