A board foot calculator measures hardwood and lumber by volume. It multiplies thickness in inches by width in inches by length in feet and divides by 12, then multiplies by the quantity. Ten boards of 2 by 6 inch by 8 foot stock are 80 board feet, and the price per board foot gives the cost.
Total board feet
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How to Use the Board Foot Calculator
- Enter the board thickness and width in inches.
- Enter the length in feet and the number of boards.
- Add a price per board foot if you want the cost.
- Read the total board feet and the cost.
Here is what each result line means:
| Result | What it means |
|---|---|
| Total board feet | Board feet for all the boards of this size. |
| Board feet per board | Board feet in a single board. |
| Total cost | Board feet times the price per board foot. |
| Board size | The dimensions the count is based on. |
For lumber bought by the piece and length, use the concrete formwork calculator for forming lumber, or the concrete footing calculator for the footing that lumber forms.
What Is a Board Foot?
A board foot is the unit lumber and hardwood are sold by. It is a volume: one board foot is 144 cubic inches, the same as a board 12 inches square and 1 inch thick, or 1 twelfth of a cubic foot.
Because it is a volume, a board foot can be any shape. A 1 by 12 at 12 inches, a 2 by 6 at 12 inches and a 1 by 6 at 24 inches are all one board foot. Pricing by the board foot lets a yard charge the same for the same volume whatever the board size.
How the Board Foot Calculator Works
The formula multiplies the thickness in inches by the width in inches by the length in feet, then divides by 12. The result for one board is multiplied by the quantity, and the price per board foot gives the cost.
- Multiply thickness by width by length.
- Divide by 12 for the board feet in one board.
- Multiply by the number of boards.
- Multiply by the price per board foot for the cost.
Rough hardwood is often sold in quarter-inch thickness steps: 4/4 is 1 inch, 5/4 is 1.25, 6/4 is 1.5 and 8/4 is 2 inches. Enter the thickness in inches, so 8/4 is entered as 2.
Board Foot Example
Suppose you need ten boards of 2 by 6 inch stock, each 8 feet long, at 4.50 per board foot.
Calculation: one board is 2 times 6 times 8 over 12, which is 8 board feet. Ten boards is 80 board feet, and at 4.50 that is about 360 in total.
The lesson: thickness and width are in inches but length is in feet, and the 12 in the formula reconciles the units.
Factors That Change Board Feet and Cost
Nominal vs Actual Size
Lumber is named by a nominal size but milled smaller, so a 2 by 4 is really 1.5 by 3.5 inches. Yards usually charge by the nominal size; use the size you are billed on.
Thickness Steps
Rough hardwood comes in quarter-inch steps, 4/4 to 8/4 and beyond. A thicker board is more board feet for the same face size.
Quantity and Length
Board feet scale with every dimension and the count, so a longer or thicker board adds up fast across a big order.
Price by Grade and Species
The price per board foot swings with species, grade and the market, so the cost is only as good as the price you enter.
Board Feet vs Linear Feet: a Comparison
The two ways to measure lumber are not interchangeable.
| Measure | What it counts | Used for |
|---|---|---|
| Board feet | Volume, including thickness and width | Rough hardwood, slabs, pricing by volume |
| Linear feet | Length only, for one size | Dimensional lumber and trim sold by the piece |
Dimensional framing is usually bought by the piece and length, not by the board foot. For that, the lumber calculator counts pieces; this tool is for volume-priced stock.
When to Use a Board Foot Calculator
Buying Hardwood
Turn a cut list into board feet and a price at the lumber yard.
Slabs and Rough Stock
Measure thick, wide boards sold by volume.
Woodworking Projects
Total the board feet for a furniture or cabinet build.
Comparing Prices
Put different board sizes on the same per-board-foot footing.
Common Mistakes with Board Feet
1. Mixing the Units
Thickness and width are in inches, but length is in feet. Putting length in inches makes the answer twelve times too big.
2. Forgetting the Quantity
The formula gives one board. Multiply by the number of boards for the order.
3. Confusing Nominal and Actual
Decide whether you are charged by nominal or actual size and be consistent, or the board feet will not match the bill.
4. Misreading Quarter Sizes
8/4 is 2 inches, not 8. Convert the quarter notation to inches before entering.
5. Trusting an Old Price
Lumber prices move. Use a current price per board foot for a realistic cost.
Accuracy and Limitations
The board foot math is exact for the inputs, but the size convention and the price are yours to set, so the cost is only as good as the figures you enter.
What it calculates
- Board feet per board and in total
- The cost at your price per board foot
- A quick board-size summary
What it does not do
- Convert nominal to actual size
- Add waste or cutting loss
- Optimize a cut list
- Price grade or species for you
How We Calculate Board Feet
Frequently Asked Questions About Board Feet
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet and divide by 12. A 2 by 6 inch board 8 feet long is 2 times 6 times 8 over 12, or 8 board feet.
What is a board foot?
A board foot is a volume of lumber equal to 144 cubic inches, the same as a 12 by 12 inch piece 1 inch thick, or one twelfth of a cubic foot.
Is a board foot the same as a linear foot?
No. A linear foot measures only length for one board size. A board foot measures volume, including the thickness and width, so it works across sizes.
What does 4/4 and 8/4 mean?
They are rough thickness in quarter-inch steps. 4/4 is 1 inch, 5/4 is 1.25, 6/4 is 1.5 and 8/4 is 2 inches. Enter the thickness in inches.
Do I use nominal or actual size for board feet?
Yards usually charge by the nominal size, so use that to match the bill. For a precise volume, such as weight, use the actual milled size.
How many board feet in a 2x4x8?
A nominal 2 by 4 inch board 8 feet long is 2 times 4 times 8 over 12, which is about 5.33 board feet.
How do I get the cost from board feet?
Multiply the board feet by the price per board foot. Eighty board feet at 4.50 is about 360.
Does board foot include waste?
No. It is the measured volume of the boards. Add your own waste or cutting allowance on top for a real order.
How many board feet are in a cubic foot?
Twelve. One cubic foot is twelve board feet, since a board foot is one twelfth of a cubic foot.
Is my data saved?
No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.
Sources
- USDA Forest Products Laboratory, Wood Handbook (wood measurement and properties).
- Oregon State University Wood Science: wood properties (lumber measurement and species data).
- BIA Technical Note 10, Dimensioning and Estimating Brick Masonry (Brick Industry Association; material estimating method).
Related Calculators
Buying lumber by the board foot?
Explore all framing calculatorsThis calculator measures board feet and cost for planning only. Lumber is sold by nominal size but milled smaller, and prices change by grade, species and market, so confirm the size and price with your supplier before ordering. Spotted an error? Let us know.