Belts/Gear Ratio

The Belt/Gear Ratio page provides a tool to quickly estimate shaft speeds of belt drives and to estimate gear ratios.

There are several ways to use this tool:

• For a belt drive system, measure the pulley diameters (any consistent , i.e., both in inches or cm) and the speed ratio will be calculated. Add the speed of the input shaft or output shaft (Hz or CPM) and the other will be calculated.

• If input and output speeds are accurately measured or desired speeds are known, enter those and the speed ratio will be calculated. Enter in one of the pulley diameters, and the other will be calculated.

• If a gear ratio is known, enter the ratio and possible gear teeth combinations will be shown by clicking on the Gear Possibilities button.

A couple things to note:

• Numbers shown in red are calculated values, and may not be changed. Change the input values to change calculated results,

• The pulley diameters are shown schematically in the illustration as an aid to remember which is the larger and which smaller.