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Kerf Waste Calculator

See how many pieces you get from a board once the saw kerf is subtracted, how much material the cuts eat, and what’s left over.

Stock length

Finished piece length

Saw kerf (blade width)

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How it works

Pieces = ⌊(stock + kerf) ÷ (piece + kerf)⌋ · Kerf loss = pieces × kerf · Leftover = stock − pieces × piece − kerf loss

Every cut turns a blade’s width of wood into sawdust — the kerf — so you can’t simply divide stock length by piece length. Each finished piece effectively needs its own length plus one kerf of clearance, which is why the count uses (stock + kerf) ÷ (piece + kerf): it accounts for the fact that the last piece doesn’t need a trailing kerf. On a full-kerf blade (about 1/8″) cutting many short pieces, the lost material adds up fast and can cost you a whole extra piece per board — a good reason cabinet shops use thin-kerf blades to boost yield. Plan cut lists with the kerf included so you buy enough stock the first time.

Worked example

A 96″ board cut into 12″ pieces with a 1/8″ (0.125″) kerf: pieces = ⌊(96 + 0.125) ÷ 12.125⌋ = ⌊7.93⌋ = 7. The kerf eats 7 × 0.125 = 0.875″, the pieces use 84″, and 11.125″ is left over — not quite enough for an eighth 12″ piece.

Frequently asked questions

Why not just divide 96 by 12?

That ignores the wood turned to dust by each cut. With a 1/8″ kerf, seven cuts remove nearly an inch of material, and near the end of a board that lost inch is often the difference between getting the next piece or not. Always subtract the kerf.

How wide is a typical kerf?

A standard full-kerf table-saw blade cuts about 1/8″ (0.125″); a thin-kerf blade cuts around 3/32″ (0.094″). Band saws cut much narrower (as little as 1/32″), and hand saws vary. Enter your actual blade for an accurate yield.

Does thin-kerf really get more pieces?

Sometimes. When you are making many cuts in expensive stock, the saved kerf can add up to an extra piece per board or reduce waste noticeably. For a few cuts the difference is negligible; for production cut lists it matters.

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This calculator is for educational purposes. Double-check important results before acting on them.