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Caster Replacement Guide

How to measure the stem size of your chair caster.

Many people have difficulty accurately measuring the grip ring stem ( mounting post ) on their chair or furniture casters. The "grip ring" is the "C" shaped metal clip which compresses when inserted in the holes in the bottom of the chair. It holds the caster in the hole. If you want to replace a caster that has a "grip ring stem", first try measuring with a ruler. Place the ruler perpendicular to the length of the stem at the middle (not near the top or the ring). Most casters that have a grip ring stem have 7/16" stem diameter. If the stem of your caster is 7/16" diameter it will measure slightly less than the 1/2" mark on the ruler.

If you measure 3/8" diameter for your Grip Ring Stem, we're sorry but we can not help you. We only sell chair casters with 7/16" diameter Grip Ring Stems which fit about 95% of all office chairs.

Please Note: Most Hon and Steel Case chairs have their own proprietary stem sizes. Please contact your chair manufacturer for proper casters if you have one of these chairs. 

Please use one of the two methods below to measure the stem diameter. Remember, measure twice - order once.

Method #1

Find the Diameter using some common tools.

Use some of the tools you have around the house to measure. If you have a set of open-end wrenches, use the wrench to check the diameter of the stem. There should be a little "wiggle" between the wrench and the stem. If you need to measure the diameter of the hole that the stem goes into, use a drill bit. Again, there should be a little wiggle but not much. Photos below will show you how it's done. Always try "American" sizes first and "Metric", only if you think it was not a good fit with the American size.

Method #2

Find the circumference to Determine the Diameter


Wrap the paper so that it overlaps the beginning edge of itself. Where the paper intersects the beginning edge, make a mark with a pencil or pen. Try to make this mark as accurately as possible. Now take the paper off and measure the paper length from the beginning edge to the mark that you made.

Using the formula d = circumference / Pi ( 3.1416 )

We've done the math for you below.

If you measured 1 3/8" - 
You need 7/16" Diameter Stems.

If you measured 1 3/16"
You need 3/8" Diameter Stems.


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