How do you compensate for kerf in a laser-cut design?

ForEducators · Researchers · Students

Updated 8 October 2026 Sources checked · Not externally reviewed

Short answer

Kerf compensation offsets the toolpath so the finished edge lands closer to the intended dimension. For a measured kerf of K, a starting geometric offset is often about K/2 from the nominal boundary, outward for an exterior part and inward into the waste for an interior opening. Check which direction your software’s offset tool moves the path before you apply a value.

Kerf compensation offsets the toolpath outward for a part and inward for an opening Two small figures and a loop. On the left, an outside profile: a dashed rectangle shows the nominal part, and a solid toolpath rectangle sits slightly outside it, offset outward by K over 2. On the right, an internal opening in a sheet: a dashed square shows the nominal opening, and a solid toolpath square sits slightly inside it, in the waste, offset inward by K over 2. The offsets are exaggerated. A legend separates nominal from toolpath, and a note says software conventions differ, so check which side it offsets. Below, a four-step loop: cut a coupon, measure it, adjust the offset, save the record, with an arrow returning from adjust to cut a coupon when the fit is off. Outside profile (the part) K/2 toolpath goes outward by K/2 Inside opening (the hole) K/2 toolpath goes inward by K/2 nominal (what you want) toolpath Software conventions differ: check which side it offsets. K is the kerf you measured. K/2 is only a starting point. Cut a coupon Measure it Adjust offset Save the record if the fit is off, go around again
The offset is exaggerated; it is tiny in real life. The toolpath moves away from the part and into the waste, so the finished edge lands nearer the size you drew. The calculation is only a start: fit also depends on the material, the joint’s dimensions and how much the real kerf varies, so test a labeled coupon on your actual stock and keep the file and process record that worked.

That calculation is only a starting point. Fit also depends on how much the material gives, the joint’s dimensions, and how much the real kerf varies with material, thickness and settings, so test on the actual stock. Build a small labeled fit coupon from the actual stock, measure it, and preserve the successful file and process record rather than applying one compensation value to every job.

Sources

  1. Rayforge (open-source laser control software documentation)Kerf CompensationUses kerf for the full width of material removed, and offsets an outside cut outward and an inside cut inward by half of it, with a consistent worked example. Its separate kerf-measuring section uses a different convention; use this page for compensation only. Link checked October 2026.
  2. University of Pennsylvania MEAM.Design (university lab guide)LaserCuttingFitsOne university design lab's notes: stock thickness varies from its nominal size, softer materials need more overlap, and fit depends on the material, the joint's dimensions and how kerf varies, so exact values need testing. Its numbers and its kerf convention are its own. Link checked October 2026.

Sources are checked by Laser TeamWork, not by an outside expert. General guidance: your machine’s manual and your school’s procedures come first. Report a correction.

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