Board Cut Calculator

A board does not yield as many pieces as the length divided by the piece size, because every cut turns a blade's width of wood into dust. This counts the kerf for you: how many pieces you really get from a board, how much offcut is left, and, if you give a quantity, how many boards the whole job takes.

The kerf is the piece everyone forgets

The saw blade has width, and every cut removes that width, the kerf, as sawdust. Cut a 96 inch board into 14 inch pieces and a plain divide says six and a bit, but with an eighth-inch kerf on each cut the real answer can be fewer, because those kerfs add up. The formula is the stock length plus one kerf, over the piece length plus one kerf, rounded down. The one kerf you add back is because the final piece has no cut after it.

Thin kerf saves whole pieces

On a long board with many cuts, the blade you choose can change how many pieces you get. A full-kerf table saw blade takes about an eighth of an inch a cut; a thin-kerf blade or a bandsaw takes half that or less. Across a dozen cuts that saved wood can be a whole extra piece. If you are breaking down a lot of stock into short pieces, a thinner blade pays for itself in yield, which this shows when you change the kerf.

Mind the offcut

What is left at the end of the board, the offcut, is not always waste. The calculator shows its length so you can decide: a long enough offcut goes back on the rack for the next job, a short one is drop. Planning your piece length against your stock length to leave a useful offcut, rather than an awkward stub, is part of cutting economically. Sometimes a slightly different piece length wastes far less across a whole board.

From one board to the whole job

Knowing pieces per board is the start; the real question is usually how much stock to buy. Give the calculator the quantity you need and it rounds up to whole boards, because you cannot buy a fraction of one, and tells you how many to get. Buy from that number, not from a rough guess, and you neither run short in the middle of a job nor overbuy and fill the rack with offcuts you did not need.

More MakerKiln tools

• cut listCut List OptimizerFit your parts onto boards or sheets with the least waste.→
• board feetBoard Foot CalculatorBoard feet and cost for a whole lumber list, with a waste allowance.→
• equal spacingEqual Spacing CalculatorSpace holes, pins or pickets evenly across a span, or divide into equal parts.→

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