How is the belt transmission ratio calculated?

The transmission ratio (i) is calculated by dividing the driven pulley diameter (d₂) by the driver pulley diameter (d₁).

Can I calculate the belt linear speed without the driver RPM?

No, calculating the linear belt speed requires both the driver pulley diameter and its rotational speed (RPM).

What units of measurement does this calculator support?

It supports millimeters, centimeters, meters, and inches for diameters, and meters per second (m/s) or meters per minute (m/min) for belt speed.

What does a transmission ratio greater than 1 indicate?

A ratio greater than 1 indicates a speed reducer, meaning the driven pulley rotates slower than the driver pulley but outputs higher torque.

Does this calculator account for belt slippage?

No, the calculations assume an ideal drive system with zero belt slip, which is typical for timing belts or properly tensioned V-belts.

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Belt Pulley Speed Ratio Calculator

Calculate the ratio, driven speed and belt linear speed of a belt drive. i = d₂/d₁ = n₁/n₂, belt speed v = π·d·n/60. Supports mm/cm/m/inch diameter units.

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1 examples

100 mm driver, 300 mm driven at 1800 rpm

i = 300/100 = 3:1 reducer, n₂ = 600 rpm, belt speed = π·0.1·1800/60 ≈ 9.425 m/s.

{"result":"i = d₂/d₁ = 300/100 = 3 (speed reducer). n₂ = 1800 / 3 = 600 rpm. Belt speed = 9.4248 m/s.","metadata":{"input":{"driverDiameter":100,"drivenDiameter":300,"driverSpeed":1800,"diameterUnit":"mm"},"result":{"ratio":3,"driverDiameter":100,"drivenDiameter":300,"ratioType":"speed reducer","drivenSpeed":600,"beltSpeed":9.4248,"beltSpeedUnit":"m/s"}}}

Inputs

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6 options

SettingsAdjust formats, ranges, numbers, and modes.6

Driver Pulley Diameter (d₁)numberRequiredDriven Pulley Diameter (d₂)numberRequiredDriver Speed n₁ (rpm)numberOptionalOptional. If provided, the driven speed and belt linear speed are computed.Diameter UnitselectOptionalBelt Speed UnitselectOptionalDecimal PlacesnumberOptional

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Belt Pulley Speed Ratio Calculator

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Key facts

Overview

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How it works

Use cases

Examples

1. Standard Speed Reducer Setup

2. High-Speed Spindle Drive

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