Board Foot Calculator
Calculate board feet of lumber from its dimensions.
Results update as you type.
How it works
A board foot calculator converts a board's dimensions into board feet, the volume unit hardwood lumber is priced and sold by. One board foot equals 144 cubic inches — the volume of a piece one foot square and one inch thick — and the tool finds it by multiplying thickness and width in inches by the length in inches, dividing by 144, and multiplying by how many identical boards you have. Board feet matter because hardwood is not sold by the running foot or the piece like softwood framing lumber; it is sold by volume, so a thick, wide plank costs far more than a thin, narrow one of the same length. Knowing the board footage lets you compare prices between suppliers, budget a project, and check that a quote is fair. A key subtlety is nominal versus actual size: rough-sawn lumber is often quoted at its nominal thickness in quarters, such as four-quarter for a nominally one-inch board, and board feet are traditionally calculated on the nominal dimensions rather than the smaller planed size, so enter the thickness your supplier prices by. This calculator gives the exact board footage of the boards you describe; it does not add an allowance for the waste created when you rip, joint and plane rough stock down to finished parts, and that loss is real — woodworkers commonly buy 20 to 40 percent more board feet than the finished project needs to cover defects, grain selection and offcuts. Furniture makers, carpenters and sawmills use board feet as the common language for pricing and ordering wood.
Board feet = (thickness in × width in × (length ft × 12)) ÷ 144 × quantity
A board foot is a unit of lumber volume equal to 144 cubic inches — one square foot of board one inch thick. To find it, the thickness and width in inches are multiplied by the length converted to inches by multiplying feet by 12, giving the board's volume in cubic inches. Dividing that by 144 converts the volume into board feet. Multiplying by the quantity of identical boards gives the total for the whole order. Because all three dimensions are brought into inches first, the formula works for any combination of nominal or actual sizes you enter.
Source:Standard construction estimation
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter thickness, width and length.
- 2
Adjust the options
Adjust quantity if they apply — sensible defaults are already set.
- 3
Read your result
Board feet updates instantly as you type — no button to press.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches, which is the same as a board one foot long, one foot wide and one inch thick. It measures the amount of wood regardless of the board's exact shape, so a one-by-twelve that is one foot long and a two-by-six that is one foot long both contain one board foot. Hardwood is priced per board foot, making it the standard unit for buying and comparing lumber.
How do I calculate board feet by hand?
Multiply the thickness in inches by the width in inches by the length in inches, then divide by 144. If the length is in feet, multiply it by twelve first to convert to inches, or use the shortcut of thickness times width times length-in-feet divided by twelve. Multiply the result by the number of identical boards. Bringing every dimension into the same unit before multiplying is the step people most often get wrong.
Should I use nominal or actual thickness?
Use the thickness your supplier prices by, which for rough hardwood is usually the nominal size quoted in quarters — four-quarter means a nominal one inch, eight-quarter means two inches. Board feet are traditionally figured on nominal dimensions, so a planed board still counts at its rough thickness. If you enter the smaller finished thickness, you will underestimate the board feet and the price. Confirm with your supplier which dimension their quote is based on.
How much extra lumber should I buy?
Plan to buy more board feet than your finished project needs, commonly 20 to 40 percent extra for furniture and cabinetry. Rough lumber loses volume when you rip, joint and plane it to final size, boards contain knots, splits and colour you cut around, and matching grain across a piece means rejecting some stock. This calculator gives the exact footage of the boards you enter, so add your waste allowance on top before ordering to avoid running short.
Is board foot the same as a linear or square foot?
No. A linear or running foot measures only length regardless of thickness or width, and a square foot measures area, while a board foot measures volume, combining all three dimensions. Two boards of the same length can have very different board footage if one is thicker or wider. This is why hardwood is sold by the board foot rather than the running foot, since it captures how much actual wood you are buying.