Orbits Per Minute (OPM)
Affiliate link — we may earn a commissionOPM is the number of small circular orbits the sanding pad completes per minute. A random-orbit sander rated at 12,000 OPM moves the pad in 12,000 tiny circles every minute. Higher OPM removes material faster. Variable-speed sanders let you dial from about 7,000 OPM (for fine finishing) to 12,000+ OPM (for aggressive stock removal). Fixed-speed sanders run at one rate, usually around 12,000 OPM. For most woodworking, 10,000 to 12,000 OPM is the working range.
Why It Matters
Variable speed matters when you work different materials. High OPM on a painted surface can melt the paint and clog the disc. Low OPM on bare hardwood takes forever. Being able to dial back for finish passes and ramp up for rough sanding saves time and sandpaper.