Enter the offset distance (in) and the shrink per inch (in/in) into the Calculator. The calculator will evaluate the Conduit Shrink. 

Conduit Shrink Formula



  • CS is the Conduit Shrink (in)
  • OD is the offset distance (in)
  • SPI is the shrink per inch (in/in)

To calculate Conduit Shrink, multiply the offset distance by the shrink per inch.

How to Calculate Conduit Shrink?

The following steps outline how to calculate the Conduit Shrink.

  1. First, determine the offset distance (in). 
  2. Next, determine the shrink per inch (in/in). 
  3. Next, gather the formula from above = CS = OD * SPI.
  4. Finally, calculate the Conduit Shrink.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

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

offset distance (in) = 30

shrink per inch (in/in) = 0.67


What is conduit shrink in electrical installations?

Conduit shrink refers to the reduction in length of electrical conduit due to bends or curves made during installation. It’s calculated by multiplying the offset distance by the shrink per inch to accommodate the change in length and ensure accurate conduit runs.

Why is calculating conduit shrink important?

Calculating conduit shrink is crucial for ensuring that electrical conduit installations are precise and efficient. It helps in avoiding material wastage, ensuring that conduits fit perfectly within the designated paths, and maintaining the integrity of electrical systems.

Can conduit shrink calculation be used for all types of conduits?

Yes, the basic principle of calculating conduit shrink can be applied to different types of conduits, including PVC, steel, and aluminum. However, the shrink per inch value may vary based on the conduit material and bending method used.

Are there tools available to help calculate conduit shrink?

Yes, there are various calculators and software tools available that can help in accurately calculating conduit shrink. These tools often require inputs like the offset distance and shrink per inch, similar to the manual calculation method described.