Seven calculators with their limits stated.
Every tool computes on the server, shows the equation it used, lists what it assumed, names every limit it touched, and stamps the formula version into the result. None of them require an email address, and none of them require JavaScript.
Grouped by the question they answer
Not by product, and not by how hard they are.
What comes out of the shaft
Kinematics and torque through a reduction, and the point the motor actually sits at.
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Gear ratio calculator
Which gear ratio produces the required output speed?
ReturnsThe required reduction, the published reductions nearest to it, the output speed each one gives, and the speed error against your target.
Cannot tell youIt cannot tell you the loaded speed, the torque you get, or whether the gearhead survives the load.
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Output torque and efficiency
Is the output torque inside the gearhead rating?
ReturnsOutput torque in three units, the torque lost in the train, and the margin against the gearhead rated output torque.
Cannot tell youIt cannot tell you whether the motor can hold that torque continuously, or how long the gearhead lasts at it.
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Operating point on the linear model
What speed and current occur at this load?
ReturnsSpeed, current, mechanical and electrical power, efficiency, and the machine constants read off the two published points.
Cannot tell youIt is a straight line between two catalog points, not a measured curve, and it says nothing about life.
Whether it survives the cycle
Loading averaged the way heat averages it, screened against a published continuous rating.
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Duty cycle and thermal screen
Can the motor hold this duty cycle?
ReturnsRMS torque, peak torque, duty fraction, an RMS current estimate, the comparison against the continuous limit, and a bench test to run.
Cannot tell youIt cannot give you a winding temperature, and it does not qualify a duty cycle. Only a thermal test does that.
Whether the machine and the motor match
The mechanism side: what the motor has to accelerate, and what the mechanism turns torque into.
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Reflected inertia and inertia ratio
Can the motor control the reflected load?
ReturnsThe mechanism inertia seen at the motor shaft, the total inertia at the motor shaft, and the inertia ratio with guidance on what that ratio means.
Cannot tell youIt cannot tell you a settling time or a controller gain, and it says nothing about friction.
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Lead-screw force
What force does this lead screw produce?
ReturnsAxial force in newtons, pounds-force and kgf, the force lost to friction, and the travel rate if you give a speed.
Cannot tell youIt cannot tell you whether the screw buckles, whether the bearings can take the load, or whether the axis holds without power.
Replacing an AC gearmotor
Not a calculation. The questions that have to be answered before a part can be proposed.
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AC to DC conversion worksheet
What does an AC-to-DC conversion require?
ReturnsA structured list of the thirteen questions that decide the conversion, which of them you have answered, and an explicit list of what still has to be measured.
Cannot tell youIt will not return an equivalent part. There is no arithmetic from an AC nameplate to a DC configuration.
What every result carries
The same contract on all seven pages, so a result can be pasted into a review and still mean something a month later.
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Inputs, echoed with units
Exactly as the calculation read them. A number typed with a unit is converted once, at the boundary, and the converted value is what you see.
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The equation, symbolic and substituted
The expression, what every symbol means, and the same expression with your numbers in it.
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Every assumption
Written out, not implied. Efficiency figures, constant-temperature assumptions, and anything held fixed that is not fixed in reality.
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Every warning
A published limit reached, an extrapolation past the data, an approximation that is degrading, or something real that sits outside the calculation.
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The formula version and the catalog version
Currently formula 2026-08-18.1 against catalog 2026-08-18.public.1. A result is reproducible or it is not evidence.
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A printable summary and a stable link
Plain text to paste into an email, and a URL that reproduces the same page with the same inputs.
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The next engineering step
What the result is not sufficient for, and what closes that gap.