What Is Kerf? Why Every Cut List Needs It
The width of your blade quietly changes every measurement. Here is how to handle it correctly.
Kerf defined
Kerf is the slot a saw removes as it cuts — the material converted to sawdust. A blade is not a line of zero width: typical kerf values are 2–3.5 mm for circular saws, 1–1.5 mm for bandsaws, and under 1 mm for laser and waterjet cutting.
Why it compounds
Cut three 2000 mm parts from a 6000 mm bar and you might assume it fits with 0 mm to spare. With a 3 mm kerf you need 6018 mm — the last part is 18 mm short. This is the single most common reason hand-made cut lists fail.
Kerf in both directions on sheet goods
On a sheet, kerf applies to both rip cuts and crosscuts, so it reduces usable width and height alike. The sheet cutting calculator reserves kerf between every part, both horizontally and vertically.
Measure your own kerf
Cut a scrap piece, measure the slot width at several points, and average. A fence-side blade with side wobble or a dull blade cuts wider than its nominal width. Enter the measured value — not the catalog value — into the kerf field.
Bottom line
Kerf awareness is the difference between a plan that works and one that costs you a re-cut. Both NestingCalc calculators make it a first-class input — use it.
Open the linear cutting calculator Open the sheet cutting calculator