Enter any two of the inner diameter, outer diameter, and diameter ratio into the calculator to determine the missing value of the hollow shaft.

Hollow Shaft Diameter Ratio Formula

The following equation is used to calculate the Hollow Shaft Diameter Ratio.


  • Where HSDR is the hollow shaft diameter ratio
  • ID is the inner diameter
  • OD is the outer diameter

To calculate the hollow shaft diameter, divide the inner diameter by the outer diameter.

To calculate for either the inner or outer diameter, use basic algebra to re-arrange the formula above. For example, solving for the ID would be:


What is a Hollow Shaft Diameter Ratio?


A hollow shaft diameter ratio is a measure of the ratio of the inner diameter to the outer diameter of a hollow tube.

How to Calculate Hollow Shaft Diameter Ratio?

Example Problem:

The following example outlines the steps and information needed to calculate Hollow Shaft Diameter Ratio.

First, determine the inner diameter. In this example, the inner diameter is measured to be 5 inches.

Next, determine the outer diameter. This outer diameter is measured to be 6 inches.

Finally, calculate the hollow shaft diameter ratio using the formula above:


HSDR = 5/6

HSDR = .8333