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Online motor sizing calculators compared

5 min read · 2026-10-22

Sizing a motor for an axis is the same arithmetic everywhere: reflect the load's inertia and friction to the motor shaft, work out the torque in every phase of the move, check peak and RMS against the motor's curve and the inertia ratio against the drive's comfort zone. The tools differ in where they run, whether they ask for an account, which mechanisms and motor kinds they know, whether they show their working, and whose catalogue they point you to at the end. This page lines up the ones an engineer finds in the first page of a search, as of October 2026 and as the makers describe them on their public pages; check the current state before relying on any row.

Side by side

Tool Made by Runs Account Mechanisms Motors Shows the formulas Vendor-neutral Cost
Cyclogram axis sizing calculator cyclogram.app Browser, metric and imperial None Ball screw, belt, rack and pinion, rotary table, pneumatic cylinder; optional gearbox Servo, stepper, BLDC, AC induction, typed in or saved to a personal list Every result, with a worked example Yes Free
Motorizer Mitsubishi Electric Windows download Varies by region A menu of common load types incl. ball screw, rack and pinion, belt Mitsubishi servos and amplifiers Results, not derivations No Free
Online sizing tools Oriental Motor Browser Required for some forms Ball/lead screw, belt, rack and pinion, index table and others, one form each Oriental Motor catalogue Results No Free
Engineering calculators Firgelli Automation Browser None Single-purpose pages: inertia ratio, pneumatic air, robot cycle time Generic A formula per page Yes Free
Inertia matching calculator Wake Industrial Browser None Load inertia, motor inertia, gear ratio Generic One formula Yes Free
SERVOsoft ControlEng (B&R distributes and trains) Windows download Licence Full drive train, up to 20 axes, incl. drives, supply and regeneration Multi-vendor databases, editable Yes Yes Paid, with a trial
Vendor suites Siemens, Rockwell, Kollmorgen, Beckhoff, Festo, SEW, Lenze and others Download or web Usually Broad That maker's catalogue Partly No Free

What each is for

Cyclogram's calculator walks one axis through six steps: the motion profile (trapezoid or S-curve, with the dwell, the move back and the rest at home), the mechanism, the motor with its peak, RMS, speed and inertia-ratio checks, the regenerated energy and brake resistor, and finally the move as a bar for a cycle chart. Every number is shown with the formula it came from and a worked example beside it, which is the point: it is written for the engineer who wants to be able to defend the result, not just copy it. It knows no manufacturer's catalogue, so the last step, picking a real motor from a real list, is yours. Nothing typed leaves the browser and there is no account.

Mitsubishi's Motorizer is the classic vendor sizing program: describe the machine and the operation pattern, pick a load type from a menu, and it proposes motors and amplifiers from the Mitsubishi range with the effective load ratio and inertia worked out. It is free and thorough, and it exists to sell Mitsubishi servos, which is reasonable if that is what you are buying. Some regional Mitsubishi sites list it as superseded, so look at your own region's page.

Oriental Motor's online sizing tools are one web form per mechanism (screw, belt, rack and pinion, index table and more), returning the torque, speed and inertia and a recommendation from their catalogue. Their own guide notes that an account is needed for the full set of forms. Good for steppers and small motors, which is their range.

Firgelli's and Wake Industrial's pages are the single-formula calculators: enter the load inertia, motor inertia and gear ratio, read the ratio. Quick and honest for one check. Single-formula pages differ in how they apply the gear ratio to the reflected inertia, so read the convention on the page before you trust the number. Neither does the full sizing.

SERVOsoft is the professional, vendor-neutral tool for whole drive trains: many axes, drives and the shared supply and regeneration between them, with open motor databases. It is Windows software with a paid licence (there is a trial, and training courses exist), aimed at the integrator who sizes machines for a living.

The vendor suites (Siemens' SIZER and TIA Selection Tool, Rockwell's Motion Analyzer, Kollmorgen's Motioneering, Beckhoff's Motion Designer, the tools from Festo, SEW and Lenze) are the natural second step. Each knows its maker's catalogue to the last option code and will produce an order list. Each also assumes you have already decided whose motor it is going to be.

A way to use them together

  1. Do the first pass in a vendor-neutral tool that shows its working, so the mechanism, the move and the torque are settled on paper before any catalogue is open. That is what the Cyclogram calculator is for; SERVOsoft if the axis count and the budget say so.
  2. Take the peak torque, RMS torque, top speed and load inertia into the vendor suite of the maker you are likely to buy from, and let it pick the real motor and drive.
  3. Put the chosen motor's numbers back into the first tool and read the margins. If the margins moved, you learned something about the catalogue, not about the machine.

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