🎯 Free Tool

Kerf Calculator

Measure your test square with calipers and get your exact kerf in seconds.

How to run a kerf test?

Cut a 100mm × 100mm square and measure it with calipers

Enter measurements

Designed size (mm)

Actual measured size (mm)

Why does kerf matter?

Kerf is the material the laser removes. Without compensating for it, joints will be loose or won't fit at all.

When to measure?

Every time you change material, thickness, or adjust power and speed. Kerf changes with every combo.

Reference Values by Material

Material	Typical Kerf	Range
MDF 3mm	0.15 – 0.20mm	CO2 40-80W
Plywood 3mm	0.15 – 0.20mm	CO2 / Diode
Acrylic 3mm	0.10 – 0.18mm	CO2 40-60W

Your Kerf

Enter measurements and click Calculate

How to measure your kerf correctly

Design a 100×100 mm square in the same material, with the same power and speed you will use for the box.
Cut it and let it cool: some materials move a little after cutting.
Measure it with digital calipers in both directions and use the average.
Enter the measurement in the calculator. The difference between 100 mm and what you measured is shared between the two sides of the cut, so the kerf is that difference divided by 2.

Example. If the square measures 99.6 mm, the difference is 0.4 mm and the kerf is (100 − 99.6) ÷ 2 = 0.2 mm.

What value is normal

As a reference, a typical CO2 cutter often gives between 0.1 and 0.3 mm, and a diode laser usually falls in a similar or slightly smaller range. It changes with the material, power, speed and focus, so measure every new combination. If the result is very high, check the focus and clean the lens.

What to do with the result

Enter the value in the Kerf field of Box Studio. The tool adjusts the size of the fingers and slots with that value. Cut a small test box before the final one:

If the fingers are loose, lower the kerf by 0.02 to 0.05 mm.
If they do not go in without hammering, raise it by the same amount.

Common mistakes

Measuring with a ruler instead of calipers: a difference of tenths of a millimetre is invisible to a ruler.
Measuring one side only: the square can come out different in X and in Y.
Using a different material than the box: plywood and MDF do not have the same kerf, nor do two thicknesses of the same material.
Cutting the test square at a different speed: it changes the kerf.

To understand why and to see values by machine, read the kerf reference table.