NEMA Stepper Size Selector
Pick the right NEMA frame (8–42) from your torque need — faceplate sizes, catalogue ranges and typical applications.
Two NEMA 17s can differ 5× in torque — the number only fixes the mounting face and bolt pattern. Within a frame, a longer stack = more torque but more rotor inertia. If your need lands at the top of a frame's range, step up a frame instead. Above ~NEMA 34, closed-loop (servo-stepper) is usually cheaper than raw size.
NEMA Size Selector computes the right NEMA stepper frame for a required holding torque — free, instant and private in your browser. Machine builders translating torque needs into orderable motor sizes use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About NEMA Stepper Size Selector
NEMA Size Selector computes the right NEMA stepper frame for a required holding torque using the standard engineering relation: NEMA n = faceplate of n/10 inch square (NEMA ICS 16); torque comes from length/winding within the frame. Worked live: 50 N·cm sits comfortably in the NEMA 17 high-torque range; 200 N·cm wants a NEMA 23. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use NEMA Stepper Size Selector
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use NEMA Stepper Size Selector?
- ✓Implements the real formula — NEMA n = faceplate of n/10 inch square (NEMA ICS 16) — with the substitution shown, not a black box
- ✓Built for machine builders translating torque needs into orderable motor sizes
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate nema size?+
The right NEMA stepper frame for a required holding torque follows NEMA n = faceplate of n/10 inch square (NEMA ICS 16); torque comes from length/winding within the frame. For example, 50 N·cm sits comfortably in the NEMA 17 high-torque range; 200 N·cm wants a NEMA 23. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Are all NEMA 17 motors the same torque?+
Not remotely — the number only fixes the 42.3 mm bolt pattern. Stack lengths from 20 to 60 mm span roughly 13 to 65 N·cm in the same frame. Match the frame for mounting, then pick length/winding for torque and current.
Bigger frame or longer motor — which is better for more torque?+
Stepping up a frame usually beats maxing out a length: you get the torque at lower current density, cooler running and less rotor inertia per N·cm. If you're at the top of NEMA 17's range, a short NEMA 23 is normally the smarter buy.
Is the NEMA Size Selector free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
Related Electronics tools
PCB Trace Width Calculator (IPC-2221)
Minimum trace width for your current and temperature rise — IPC-2221 formula with copper weight, layer choice and a step-by-step worked example.
● LiveMicrostrip Impedance Calculator
Z₀ of a surface microstrip from width, height and εr (IPC-2141A), plus effective dielectric constant and propagation delay.
● LiveStripline Impedance Calculator
Characteristic impedance of an embedded stripline trace from geometry and εr — the inner-layer companion to the microstrip tool.
● Live