Board Foot Calculator

A board foot is a lumber volume unit equal to a piece 1 inch thick, 12 inches wide, and 12 inches long. One board foot is 144 cubic inches of lumber. It is used to price and order hardwood and rough-sawn lumber where boards come in random widths and lengths.

Board feet per piece equals thickness in inches multiplied by width in inches multiplied by length in feet, then divided by 12. Multiply by quantity for total board feet. If you measured length in inches, divide by 144 instead of 12 (because 12 × 12 = 144).

Board feet are almost always calculated with nominal (rough) dimensions, not the smaller actual dimensions after planing. A 1×6 board that is actually 3/4 inch by 5.5 inches is still billed as a 1×6 for board-foot purposes. Use the nominal dimensions when ordering lumber.

The cost estimate is total board feet multiplied by your entered price per board foot. It reflects only the lumber cost, not delivery, sales tax, surfacing or planing upcharges, kiln drying surcharges, or species premiums. Treat it as a planning figure and confirm with the supplier.

Yes, in most projects. Crosscutting to length and ripping to width produces offcuts. A common rule of thumb is to order 10 to 20 percent more lumber than the finished project requires. Order more for projects with lots of small parts, knot avoidance, or matched grain.

One board foot is 144 cubic inches. Multiplying thickness (in) by width (in) by length (in) gives volume in cubic inches; dividing by 144 converts to board feet. The shorter form (thickness × width × length-in-feet ÷ 12) is the same math: 12 inches per foot × 12 inches in the unit width cancels one factor of 12.