CNC & 3D printer calculators
Small, fast tools for dialing in CNC machines and 3D printers. The math runs entirely in your browser, no sign-up and no tracking.
Steps per mm calculator
steps/mm and steps/° for leadscrews, belts and rack & pinion, with copy-ready GRBL and Marlin config lines and a pitch-vs-lead explainer.
Open →Tap drill sizes
Tap drill, clearance hole, counterbore and heat-set insert hole for UNC, UNF and metric threads, with the % thread every drill cuts.
Open →Feeds & speeds
Spindle RPM and feed rate from surface speed, tool diameter and chip load, with material starting points.
Open →Belt tension
Tension GT2 / GT3 belts by plucking the span, target tension to frequency, or frequency to tension.
Open →Lathe RPM calculator
Optimal spindle speed from workpiece diameter, material and tool type. Covers HSS and carbide, metric and imperial.
Open →Lathe motor power calculator
How much motor power a turning job needs, from depth of cut, feed rate and material. Includes drive efficiency and motor adequacy check.
Open →Built for the workshop, mobile-first, keyboard accessible, and light on data. No accounts, no cookies.