Get unique, complex parts easily. No matter your requirements, Master Spring creates hard-to-produce coil springs and wire forms.

Custom Wire Forms

Let us help you create the custom wire form you need, from S-hooks and J-hooks to utility hooks and more.


We work closely with customers across a wide range of industries, helping them design and manufacture made-to-order parts.

Master Spring Advantage

Why choose Master Spring? We prioritize customer-focused collaboration, modern equipment and the latest technology to make your parts per print.

Compression Spring Measurement Guide

Compression spring dimensions are defined as the measurements critical to the design of a compression spring. There are endless compression spring designs, and knowing how to find precise measurements will help you determine the best spring for your needs.

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illustration of how to measure compression spring force

5 Compression Spring Dimensions

To measure a compression spring, you can use dial calipers, a micrometer, a ruler or tape measure for larger springs. When measuring a compression spring, you must determine the following five elements:

  1. Outer diameter is measured by placing your dial calipers on the outside of the coil’s width.
  2. Inner diameter is defined as the width of the inside of a coil spring’s diameter measured from the center of the helix. Sometimes, inner diameter can be difficult to measure accurately. The formula to calculate inner diameter is I.D. = O.D. – 2d where 2d is two wire diameters.
  3. Defined as the full length of an uncompressed spring, free length is easy to find. To measure, place your calipers on the full length of the spring.
  4. Wire diameter is found by placing your calipers on the wire in the center of your spring.
  5. Total coil count is defined as each full rotation and the remainder of the last coil.

As you learn about taking accurate spring dimensions, explore compression spring terminology for helpful symbols and definitions.

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Need a custom wire form or coil spring? We make it work. Fill out the contact form and a representative will respond within 1 business day. Please attach a PDF or CAD file with your request to quote.


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Your Team For Innovative Wire Forming

We provide solutions for complex, high-quality
wire forms and coil springs.

78 Congress Circle West, Roselle, IL 60172

P: 708.453.2570 | Contact Us

We do not stock standard springs,
we make made-to-order custom springs.