Calculate gear module, pitch diameter, tooth count, circular pitch, and diametral pitch for spur gears using metric or imperial dimensions.

Required inputs are marked *. Module is reported in millimeters per tooth. Use pitch-circle diameter, not outside diameter.
Enter pitch-circle diameter and a whole number of teeth.
A physical gear must have a positive whole-number tooth count.
Module
Pitch diameter
Number of teeth
Circular pitch
Diametral pitch
Assumes the basic spur-gear relation using transverse pitch diameter. Helical gears may require normal and transverse module conversion, and module alone does not confirm pressure angle, profile shift, backlash, or load capacity.

Gear Module Formula

The following formula is used to calculate the gear module:

M = (D) / (N)

Variables:

  • M is the module (mm)
  • D is the pitch diameter (mm)
  • N is the number of teeth

To calculate the gear module, divide the pitch diameter (D) by the number of teeth (N).

What is Gear Module?

Gear module is a unit of measure that indicates the size of the teeth in a gear. It is defined as the ratio of the pitch diameter to the number of teeth. The module determines the size of the gear tooth and the gear’s pitch circle. It is a critical parameter in gear design and is used to ensure that gears mesh correctly and operate smoothly.

How to Calculate Gear Module?

The following steps outline how to calculate the Gear Module:

  1. First, measure or determine the pitch diameter (D) of the gear in millimeters.
  2. Next, count the number of teeth (N) on the gear.
  3. Use the formula M = D / N to calculate the module (M).
  4. Finally, enter the values into the calculator above to verify the module.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Pitch diameter (D) = 200 mm

Number of teeth (N) = 40