About Gear Ratio

The gear ratios can be defined as the relationship between the number of teeth on two different gears meshed together or the circumference of two pulleys connected with a drive belt.

Generally the number of teeth on a gear is also proportional to the circumference of the gear wheel, so the bigger the wheel, the more teeth it has. Therefore the gear ratio can also be explained as the relationship between the circumference of both wheels.

Explanation of the Term
The concept of gear ratio can be well explained with the help of an example as follows :
Suppose a smaller gear has 12 teeth, while the larger gear has 24 teeth. Therefore the gear ratios between the smaller and the larger teeth is 12/24 or 1:2.
The first number in the ratio is generally the gear that power is applied to. The ratio also means that for one revolution of the smaller gear, the larger gear has made 1/2 or 0.50 revolutions. This further implies that the larger gear turns slowly as compared to the smaller one.