Laser speed units: converting mm/s, m/min and percent settings

Laser controllers speak in different units, and converting between them wrong is how jobs get ruined.

mm/s to m/min: multiply by 0.06. A 30 mm/s engrave speed is 1.8 m/min — the same number on machines that display minutes instead of seconds.

mm/s to in/s: divide by 25.4. Roughly 1.18 in/s for that same 30 mm/s setting.

Percent power vs mm/s coupling: many controllers couple speed percent to power percent. A "50% speed" setting means half the machine's maximum rate, not half of your last job's rate. Always check what the machine's maximum is before translating a forum recommendation.

The practical trap: forums and YouTube tutorials quote settings in the author's units. A 300 mm/s recommendation for a diode is not a 300 in/min recommendation for a CO2, even though the numbers rhyme. Convert, then test on scrap.

Speed and depth couple: lowering speed raises effective power per unit length, so a slower pass is not just slower — it cuts deeper and widens the kerf. When a forum setting gives you excessive charring, raise the speed before dropping power; the kerf stays narrower.

Material baselines worth memorizing: 3 mm plywood typically engraves around 200-350 mm/s at moderate power on a 10 W diode, while clear acrylic needs markedly less speed for a clean cut because it melts rather than burns. Basswood sits between them. Treat these as starting points, not gospel: your machine's actual output power, lens cleanliness and air assist all shift the numbers.

Air assist changes the math: a focused air stream removes smoke from the beam path and cools the cut edge, which usually lets you run faster for the same clean result. If you add air assist to a machine tuned without it, re-run your test grid rather than trusting old settings.

Charts that put common materials, speeds and power settings side by side in consistent units are maintained at CutChart, including a unit conversion worksheet that shows the arithmetic for each pair, so a recommendation quoted in unfamiliar units takes seconds to translate and test.