Kerf Explained: Compensating for Laser and CNC Cut Width
Kerf is the width of material removed by the cut. It is small, but joints that depend on a tight fit notice it immediately.
Published by the Heartline Works team · Last reviewed 2026-10-02 · Editorial policy
Laser kerf is commonly a fraction of a millimetre and depends on the material, thickness, power, speed and focus. CNC kerf equals the bit diameter. Measure rather than assume.
Measuring kerf
- Cut a row of 10 identical squares of known size, side by side with no gap.
- Measure the total width of the cut pieces.
- Kerf ≈ (design width − measured width) ÷ number of cuts.
Compensating
- For outside shapes, offset the path outward by half the kerf.
- For holes, offset inward by half the kerf.
- For press-fit joints, test slot widths on scrap first.
Frequently asked questions
Does every machine have the same kerf?
No. Test with your material.