CNC Engineering
Calculators
Free, instant, browser-based engineering calculators for CNC machinists, machine builders, and hobbyists.
No sign-up required — all calculations run locally in your browser.
Available Calculators
Feeds & Speeds Calculator
Calculate optimal spindle RPM and feed rate for any end mill, drill, or router bit.
Material presets for aluminum, steel, stainless, wood, plastic and brass.
RPM • Feed Rate • MRR
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Steps per mm Calculator
Find the exact steps/mm value for your 3D printer or CNC firmware. Covers leadscrews,
ballscrews, and GT2/HTD belt drives. Outputs Marlin M92 config lines.
Marlin • GRBL • RepRapFirmware
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Ballscrew Critical Speed
Determine the maximum safe RPM before ballscrew whirling resonance occurs.
Supports Fixed-Free, Fixed-Simple, and Fixed-Fixed end conditions with DN value check.
Whirling • DN Value • Safety Factor
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Ballscrew Axial Force
Convert motor torque to linear cutting force (N / kgf / lbf). Ballscrew, ACME, and
custom efficiency. Reverse calculation: find required torque for a target force.
N • kgf • lbf • N·m • oz·in
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Spindle RPM & Surface Speed
Bi-directional: calculate RPM from surface speed, or surface speed from RPM.
Material presets with min/max recommended speed bands and status indicator.
RPM • SFM • m/min
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