Pulley Speed Calculator
Driven pulley rpm from the diameter ratio
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Need a fast answer on driven pulley rpm from the diameter ratio? Pulley Speed Calculator answers with the steps beside it. Drop Driver Diameter (mm), Driver Speed (rpm) and Driven Diameter (mm) into Pulley Speed — the figure refreshes as you type. Pulley Speed puts the headline number first. Students and professionals reach for Pulley Speed when speed matters. No account is needed for Pulley Speed. The browser does the arithmetic. Pulley Speed is part of the Engineering collection on CalcProMaster, alongside pulley speed calculator rpm diameter ratio belt drive driven sheave, free online pulley speed calculator and more. Pulley Speed has no learning curve. The fields are labeled. Pulley Speed is free, instant and local.
What does the Pulley Speed Calculator do?
Pulley Speed Calculator works out the driven speed from the Driver Diameter, Driver Speed, and Driven Diameter, using Engineering conventions. With the defaults, pulley speed calculator gives a driven speed of 875.0 rpm.
- Inputs: Driver Diameter, Driver Speed, and Driven Diameter.
- Output: the driven speed, together with the chain that produced it.
- Method: the published Engineering relationship between the Driver Diameter, Driver Speed, and Driven Diameter and the driven speed.
Quick answer
pulley speed calculator returns a driven speed of 875.0 rpm with the default inputs (driver diameter of 100, driver speed of 1,750, driven diameter of 200).
How does the Pulley Speed Calculator work?
Pulley Speed Calculator computes the driven speed directly from your inputs — the Driver Diameter, Driver Speed, and Driven Diameter feed the formula. Your numbers stay in the tab and the driven speed recalculates the moment a field changes.
How the Pulley Speed Calculator works
A result from Pulley Speed Calculator is meant to be reproduced, not just read — the Driver Diameter, Driver Speed, and Driven Diameter, the Engineering formula and the step list all sit on one screen.
Using the Pulley Speed Calculator
- Driver Diameter — one of the values pulley speed builds from; the result reflects exactly what you type.
- Driver Speed — used in the first pulley speed stage, so entering it accurately beats any later refinement.
- Driven Diameter — read as written by the Engineering formula — no scaling, no conversion of the number.
- When the output on pulley speed looks plausible but not quite right, check the units line first — a scale error shows up there before anywhere else.
- Nudge each Driver Diameter, Driver Speed, and Driven Diameter on the pulley speed page in turn and note how far the output moves; the ranking rarely matches intuition.
The formula behind the result
Where the Engineering method allows more than one common convention, Pulley Speed Calculator uses the one named on the label and computes the driven speed with it from the first term to the last.
Worked example: with driver diameter of 100, driver speed of 1,750, driven diameter of 200, this pulley speed calculation returns Driven Speed: 875.0 rpm. The same run reports Speed ratio: 2.00:1 | Belt speed ≈ π × d₁ × n₁ = 550 m/min (same on both pulleys).
The steps it follows:
- Formula: n2 = (d1 × n1) ÷ d2 — belt speed is equal on both pulleys
- d1 × n1 = 100 × 1750 = 175000
- ÷ d2 (200) = 875.0 rpm
- A larger driven pulley turns slower but delivers more torque — power (ignoring losses) stays the same
Understanding the result
Decimal places on pulley speed beyond the precision of your own Driver Diameter, Driver Speed, and Driven Diameter are display, not information.
Where it helps
Pulley Speed Calculator suits settling a question you keep coming back to, running an alternative scenario, and checking the arithmetic without a spreadsheet — the kind of question that arrives once a week and deserves a defensible number.
Common mistakes
Quoting the driven speed without the Driver Diameter, Driver Speed, and Driven Diameter that produced it is the error that survives longest, because nobody downstream can check it.
Tip: Pulley Speed Calculator returns Driven Speed: 875.0 rpm at its defaults; double the Driver Diameter (mm) and it returns Driven Speed: 1750.0 rpm.
Assumptions and limitations
Very large or very small inputs in Pulley Speed Calculator can push the figure beyond what is practically meaningful — sanity-check extreme values before relying on them.
Why use this calculator
Because the working is visible: Pulley Speed Calculator shows each operation behind the driven speed in the steps panel, so you can verify the result instead of trusting a black box.
Frequently Asked Questions
Which figure does pulley speed calculator produce?
Set the Driver Diameter, Driver Speed, and Driven Diameter on Pulley Speed Calculator to your own case and the figure re-derives from scratch — no stored state and no cached figure from an earlier run. Because the output arrives with supporting figures and a full step list, Pulley Speed Calculator gives you context rather than a single bare number.
What calculation does the page perform?
The first steps are formula: n2 = (d1 × n1) ÷ d2 — belt speed is equal on both pulleys, then d1 × n1 = 100 × 1750 = 175000. Pulley Speed Calculator handles the arithmetic in the order the steps panel lists it, and no correction factor is applied on top of the formula.
Which fields does the Pulley Speed Calculator need?
Pulley Speed Calculator asks for Driver Diameter, Driver Speed, and Driven Diameter and nothing more.
If the Driver Diameter (mm) doubles, what follows?
At the defaults Pulley Speed Calculator returns Driven Speed: 875.0 rpm; doubling Driver Diameter (mm) to 200 moves it to Driven Speed: 1750.0 rpm.
How should the the Pulley Speed Calculator result be read?
The main number the pulley speed calculator returns is the driven speed for your exact inputs. The output Pulley Speed Calculator reports is only as complete as the inputs: anything the page does not ask for sits outside the calculation.
Where does the Pulley Speed Calculator fit in day-to-day work?
Where Pulley Speed Calculator earns its keep: settling a question you keep coming back to, running an alternative scenario, and checking the arithmetic without a spreadsheet, and the smaller questions that sit around them. The pulley speed page keeps your last inputs in the URL, so a reload restores the driven speed instead of an empty form.
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