🪵 Board Foot Calculator
By ToolNimba Editorial Team · Updated 2026-06-19
A board foot is 144 cubic inches of lumber (12 in x 12 in x 1 in). Board feet = thickness x width x length in inches, divided by 144. Add a 10 to 15 percent waste allowance when buying.
A board foot is the unit hardwood lumber is sold in, and it is easy to mix up with a linear foot or a square foot. This calculator does the conversion for you: enter the thickness and width in inches, the length in feet or inches, and how many boards you are buying. You get the total board feet, plus the cost if you add a price per board foot. It is the fastest way to check a lumber quote or work out how much to order for a project.
What is the Board Foot Calculator?
A board foot (often shortened to BF or bd ft) is a measure of lumber volume, not length or area. One board foot equals 144 cubic inches: a piece of wood 12 inches long, 12 inches wide and 1 inch thick. The same volume can take many shapes, so a board 1 inch by 12 inches by 1 foot, a board 2 inches by 6 inches by 1 foot, and a board 1 inch by 6 inches by 2 feet are all exactly one board foot. Hardwood lumber yards quote prices per board foot precisely because it captures volume regardless of the cut.
The formula is simply the volume in cubic inches divided by 144. With every dimension in inches, board feet = (thickness x width x length) / 144. Because lumber length is usually given in feet, there is a handy shortcut: board feet = (thickness x width x length in feet) / 12, since 144 cubic inches divided by 12 inches per foot leaves 12. Both versions give the same answer, the calculator above uses whichever unit you pick for the length field.
One point that trips people up is nominal versus actual size. A board sold as a '1x6' or a '2x4' is named for its rough-sawn size before drying and planing, but the finished board is smaller, a 2x4 is actually about 1.5 by 3.5 inches. For pricing, hardwood is normally measured by its rough (nominal) thickness, and thickness under one inch is still counted as a full inch. When in doubt, ask the supplier which dimensions their board-foot price is based on so your estimate matches their invoice.
When to use it
- Checking a hardwood lumber quote so you know whether the price per board foot is fair.
- Working out how many board feet a furniture or woodworking project needs before you shop.
- Comparing two boards of different sizes on a true volume (and therefore cost) basis.
- Estimating the total material cost of a stack of lumber from a single price per board foot.
How to use the Board Foot Calculator
- Enter the board thickness in inches (for example 1 for a 1x board, 2 for a 2x board).
- Enter the board width in inches.
- Enter the length and choose feet or inches from the unit dropdown.
- Set the quantity (number of identical boards) you are buying.
- Optionally add a price per board foot to see the total and per-board cost.
Formula & method
Worked examples
You are buying ten boards, each 1 inch thick, 6 inches wide and 8 feet long, at $4.50 per board foot.
- Convert length to inches: 8 ft x 12 = 96 in
- Board feet per board = (1 x 6 x 96) / 144 = 576 / 144 = 4 BF
- Total board feet = 4 x 10 = 40 BF
- Cost = 40 x $4.50 = $180.00
Result: 40 board feet total, $180.00 (4 BF and $18.00 per board)
You need five 2 in x 10 in x 12 ft boards priced at $3.20 per board foot.
- Using the feet shortcut: board feet = (thickness x width x length in feet) / 12
- Board feet per board = (2 x 10 x 12) / 12 = 240 / 12 = 20 BF
- Total board feet = 20 x 5 = 100 BF
- Cost = 100 x $3.20 = $320.00
Result: 100 board feet total, $320.00 (20 BF and $64.00 per board)
Board feet for one board by nominal size and length
| Nominal size | 8 ft | 10 ft | 12 ft |
|---|---|---|---|
| 1 in x 4 in | 2.67 BF | 3.33 BF | 4.00 BF |
| 1 in x 6 in | 4.00 BF | 5.00 BF | 6.00 BF |
| 1 in x 8 in | 5.33 BF | 6.67 BF | 8.00 BF |
| 2 in x 4 in | 5.33 BF | 6.67 BF | 8.00 BF |
| 2 in x 6 in | 8.00 BF | 10.00 BF | 12.00 BF |
| 2 in x 10 in | 13.33 BF | 16.67 BF | 20.00 BF |
Common lumber units compared
| Unit | What it measures | Used for |
|---|---|---|
| Board foot | Volume (144 cubic inches) | Hardwood lumber pricing |
| Linear foot | Length only | Trim, moulding, dimensional lumber |
| Square foot | Surface area | Flooring, sheet goods, decking coverage |
Common mistakes to avoid
- Confusing board feet with linear feet. A linear foot only measures length, while a board foot measures volume. Two boards of the same length can hold very different amounts of wood, so always price hardwood by the board foot, not the running foot.
- Dividing by 12 when the length is in inches. The divide-by-12 shortcut only works when the length is in feet. If every dimension is in inches you must divide by 144. Mixing the two inflates or shrinks the result by a factor of twelve.
- Using the finished (actual) size instead of nominal. A 2x4 is really about 1.5 by 3.5 inches once planed, but hardwood is usually priced on its rough nominal size. Check which dimensions your supplier bills on so the estimate matches the invoice.
- Forgetting a waste allowance. Offcuts, knots, splits and trimming to length all eat into usable wood. Order roughly 10 to 15 percent more board feet than the project drawing calls for so you are not caught short.
Glossary
- Board foot (BF)
- A unit of lumber volume equal to 144 cubic inches, the same as a piece 12 in long, 12 in wide and 1 in thick.
- Nominal size
- The rough-sawn size a board is named for (such as 2x4) before it is dried and planed to a smaller finished size.
- Linear foot
- A measure of length only, one foot along a board regardless of its width or thickness.
- Quarter (4/4, 8/4)
- Hardwood thickness expressed in quarter-inches: 4/4 is one inch, 8/4 is two inches rough.
- Waste allowance
- Extra material added to an order to cover offcuts, defects and trimming, usually 10 to 15 percent.
Frequently asked questions
How do you calculate board feet?
Multiply the thickness, width and length in inches, then divide by 144. For example a board 1 inch thick, 6 inches wide and 96 inches (8 feet) long is (1 x 6 x 96) / 144 = 4 board feet. If the length is in feet, divide by 12 instead of 144.
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches. It is the volume of a board 12 inches long, 12 inches wide and 1 inch thick. Hardwood is sold by the board foot because it measures the actual amount of wood regardless of how the board is cut.
Is a board foot the same as a linear foot?
No. A linear foot measures length only, while a board foot measures volume (thickness x width x length). Two boards of equal length can contain very different amounts of wood, so they are priced differently per board foot.
Should I use the nominal or actual size?
Hardwood lumber is normally measured and priced by its rough nominal size, and thickness under one inch is counted as a full inch. Dimensional softwood (a 2x4 and so on) is named nominally too. Ask your supplier which dimensions their board-foot price is based on.
How much extra lumber should I order?
Add roughly 10 to 15 percent to your calculated board feet to cover offcuts, knots, splits and trimming to length. For intricate or short pieces with lots of waste, allow even more.
How do I find the total cost of my lumber?
Multiply the total board feet by the price per board foot. This calculator does it automatically when you enter a price, and also shows the cost per individual board so you can compare options.