Motors run at a specific revolutions per minute (RPM) and a speed reducer is needed if you want to keep that motor, but have a lower RPM. Calculating the RPM resulting from a motor and speed reducer assembly requires only basic mathematical knowledge.

- Skill level:
- Easy

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### Things you need

- Motor base RPM
- Speed reducer ratio

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## Instructions

- 1
Write down the rated RPM of your motor; for example, 5000 RPM.

- 2
Write down the ratio of the speed reducer; for example, 12:5.

- 3
Calculate the reduction by dividing 12 by 5, which equals 2.4.

- 4
The RPM of the assembly is the RPM motor divided by the reduction. In our example, it would be 5000 RPM/2.4 = 2083 RPM.

#### Tips and warnings

- The ratio of a reducer will always be in the form of A:B, where A>B.
- The RPM found should always be lower than the base RPM of the motor. If it is not, either redo your calculation or make sure you did not get a speed multiplier instead of a reducer.