Guide to Measuring Extension Springs

Thank you for choosing W.B. Jones as your spring resource. In this guide, we will be covering how to measure extension springs.

Tools we recommend you have before you start are:

  • A micrometer, which should be used whenever possible
  • Calipers
  • A ruler or tape measure for large springs

Measure the wire diameter.

We recommend that you measure the wire diameter in two different spots using a micrometer and take the average. This will allow for precise readings and accurate ordering.

For this spring, the wire diameter is .092 inches.

Measure the outside diameter.

This is commonly referred to as “OD”. When possible, you should measure for the oustide diameter in the middle of the spring because the end coils tend to run large.

The “OD” of this spring is .867 inches.

Measure the body length.

The body of an extension spring is considered the coiled portion. It does not include the hooks or loops. For this spring we’ll use a ruler, but for smaller springs using calipers or a micrometer is the best option.

For this spring the body length is 4.791 inches.

You can also provide the number of coils when using our online form. Remember to count each full rotation.

Measure the overall length of the spring.

This is the length over the top of each end or outside to outside.

The overall length of this spring is 6.055 inches long.

Now you will have all the information required to measure your extension spring accurately.

Thank you for reading our guide and if you find yourself holding a spring like the one below, which is not easily measurable or describable we have members on staff who are always here to help.