Board Foot Calculator
Calculate board feet from lumber dimensions. Enter thickness, width, length, and quantity to determine total board footage for your woodworking project.
About this calculator
A board foot is the standard unit lumber is priced and sold by in North America — one board foot is the volume of a piece 1 inch thick, 12 inches wide, and 12 inches long, which works out to 144 cubic inches. This calculator takes your lumber's thickness and width in inches and its length in feet, multiplies the three together, and divides by 12 to convert the inch-based thickness and width into the same 12-inch reference the board-foot unit is built on. Multiply that per-piece figure by quantity to price out an entire order, or by the number of boards in a project to check whether you're buying enough.
Because the formula multiplies thickness, width, and length together, a ten percent bump in any one of them alone raises the board-foot total by ten percent too — no single dimension has more mathematical pull than the other two. In practice, thickness often has the biggest real-world swing because lumber is commonly sold in fixed nominal thicknesses (4/4, 5/4, 6/4, 8/4) that jump in bigger absolute steps than width usually does. This calculator uses whatever thickness and width you enter directly — it does not distinguish nominal lumber sizes (a "2x4" is actually 1.5 by 3.5 inches after milling) from actual measured dimensions, so if you're pricing dimensional lumber by its nominal name rather than a tape measure, enter the actual milled size for an accurate board-foot count, not the nominal one.
Inputs
Results
Board Feet per Piece
4 BF
Total Board Feet
4 BF
How to Use This Calculator
- Enter Thickness, Width, and Length.
- Set Quantity.
- Review Board Feet per Piece (BF) and Total Board Feet (BF).
- Use Total Linear Feet (ft) and Total Cubic Feet (cu ft) to inform your decision.
- Use the chart to visualize the results and explore different scenarios by adjusting inputs.
How the result changes with Thickness
| Thickness | Board Feet per Piece | Total Board Feet |
|---|---|---|
| 0.5 | 2 BF | 2 BF |
| 0.75 | 3 BF | 3 BF |
| 1.5 | 6 BF | 6 BF |
| 2.5 | 10 BF | 10 BF |
What each input means
- Thickness
- Lumber thickness in inches (nominal or actual)
- Width
- Lumber width in inches
- Length
- Lumber length in feet
- Quantity
- Number of identical pieces
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersThickness = 1, Width = 6, Length = 8, Quantity = 1 = 4 input(s) provided
- Calculate Board Feet per PieceBoard Feet per Piece4 = 4
- Calculate Total Board FeetTotal Board Feet4 = 4
- Calculate Total Linear Feet8 = 8
- Calculate Total Cubic FeetTotal Cubic Feet0.333 = 0.333
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why divide by 12 instead of 144?
Because length is entered in feet while thickness and width are entered in inches. Thickness times width times length gives a mixed-unit figure that is already off by a factor of 12 from cubic inches, so dividing by 12 (not 144) lands on true board feet. If you instead multiply all three dimensions in inches, you would divide by 144 to reach the same number.
Should I use nominal or actual lumber dimensions?
Use whichever one matches how you're being charged. Rough-sawn or nominal-size lumber (like a "1x6" board) is usually priced by its nominal, pre-milling dimensions, while a board you've measured with a tape after planing has smaller actual dimensions. This calculator does not know which convention you're using — it multiplies exactly what you enter, so match your input to your supplier's pricing basis.
Does quantity affect the board feet per piece?
No. Board Feet per Piece is calculated purely from thickness, width, and length — quantity only scales the Total Board Feet, Total Linear Feet, and Total Cubic Feet figures. Entering 50 identical boards gives the same per-piece board footage as entering 1, just multiplied by 50 for the totals.
What is total cubic feet used for if board feet already measures volume?
Board feet is a lumber-industry pricing convention, while cubic feet is the general physical volume unit used for kiln capacity, shipping calculations, or storage planning. The conversion is exact: one board foot equals 1/12 of a cubic foot, so this calculator derives cubic feet directly from the total board feet for those other planning needs.
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