Board Foot Calculator

Calculate board feet and material costs. Thickness and width in inches, length in feet. Supports fractions.

Dimensions

Thickness and width in inches, length in feet. Supports fractions like "3/4" (0.75), "1 1/2" (1.5), or decimals like "0.75"

Thickness (inches)

Width (inches)

Length (feet)

Cost per Board Foot (optional)

Results

Enter dimensions and click Calculate to see results

About the Board Foot Calculator

A board foot is the standard unit for buying and pricing hardwood lumber in North America. This calculator converts a board's thickness, width, and length into board feet and, optionally, a total cost — with support for fractions, mixed numbers, and decimals so you can enter real shop measurements directly.

What is a board foot?

One board foot equals 144 cubic inches of wood — for example a piece 1 inch thick, 12 inches wide and 12 inches long (1 ft²). It is a measure of volume, not surface area, so thickness matters just as much as the face dimensions. Hardwood is almost always sold by the board foot, while softwood and sheet goods are typically sold by the linear foot or by the sheet.

Because it is a volume measure, a 2-inch-thick board contains twice the board footage of a 1-inch board of the same width and length, and costs roughly twice as much even though it looks the same from the face.

The board foot formula

Board feet = (thickness in inches × width in inches × length in inches) ÷ 144. When length is given in feet, the equivalent shortcut is (thickness in inches × width in inches × length in feet) ÷ 12, which is what this calculator uses. Multiply the result by the number of identical boards to get your total, and by the price per board foot to estimate cost.

A common point of confusion is rough vs. surfaced (S4S) lumber. Board feet are usually figured on the nominal rough thickness — quoted in quarters, where 4/4 means one inch, 5/4 means 1¼ inch, 8/4 means two inches — even after the board has been planed thinner. Price by the thickness you are charged for, not the final dressed thickness.

Tips for accurate estimates

Measure width at the narrowest point of a rough board, and round partial inches honestly — lumber yards often round up to the next quarter inch. Add 15–25% to your total for waste, defects, and offcuts on a real project, and a little more if you are working around knots or matching grain. Entering price per board foot lets the calculator turn your cut list into a quick budget before you get to the till.

Example: pricing a walnut board

You are pricing a piece of 8/4 (two-inch) black walnut that measures 7 inches wide and 6 feet long, quoted at $12 per board foot.

Thickness = 2 in, width = 7 in, length = 6 ft.
Board feet = (2 × 7 × 6) ÷ 12 = 84 ÷ 12 = 7 board feet.
Cost = 7 board feet × $12 = $84.

The board contains 7 board feet and costs about $84 before tax and waste allowance.

Frequently asked questions

What is the difference between a board foot and a linear foot?

A linear foot only measures length, ignoring width and thickness. A board foot measures volume (144 cubic inches), so two boards of the same length can contain very different board footage if their widths or thicknesses differ. Hardwood is sold by the board foot; trim and dimensional softwood is often sold by the linear foot.

Do I use rough or finished thickness for board feet?

Use the thickness you are billed for, which is usually the rough/nominal thickness expressed in quarters (4/4, 5/4, 8/4). A 4/4 board planed to ¾ inch is still sold as one inch thick, so calculate board feet on the one-inch figure.

Can I enter fractions like 3/4 or 1 1/2?

Yes. The calculator accepts whole numbers, decimals (0.75), simple fractions (3/4), and mixed numbers (1 1/2). It converts them automatically, so you can type measurements exactly as they appear on your tape.

How much extra should I order for waste?

A typical allowance is 15–25% over your finished board-foot total to cover saw kerf, defects, snipe, and grain matching. Order toward the higher end for figured wood, narrow stock, or projects where colour and grain need to match across boards.