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How to Measure the Stem Size of Your Caster

How to Measure the Stem Size of Your Caster

Whether you’re assembling a new piece of furniture or replacing worn-out casters on your office chair, understanding the details is essential. 

Why? Because, as they say, the devil is in the details. An incorrect stem size can lead to a poor fit and potential damage to your furniture over time.

In this comprehensive guide, we will guide you through the process of accurately measuring the stem size of your caster. Regardless of whether you’re a DIY enthusiast or a beginner, this guide is designed to help you achieve accurate measurements each time. 

We have tried to demystify the process and simplified it so everyone from beginners to professionals can take accurate measurements. We will discuss three effective methods, each using common tools you likely have around the house.


So, let’s roll up our sleeves and get started.

Different Stem Types and Their Measurement Considerations

To ensure precise measurements, it’s essential to understand the structural differences between various stem types. Knowing these differences will help you better interpret your measurements and choose the appropriate replacement caster, ultimately ensuring the longevity and stability of your furniture. 

There are three different types of stem casters

Grip Ring Stems

These stems feature a ‘ring’ that compresses upon insertion into the furniture, providing a secure fit. The ring can create an illusion of a larger diameter, so when measuring, ensure you measure the stem below the ring. A caliper would be a more precise tool for this kind of stem.

How to Measure the Stem Size of Your Caster, Caster City

Grip Neck Stems

These have a narrow, elongated stem that expands into a wider, rounded top. Again, make sure to measure the stem part only, not the wider top. These stems often fit into a socket, so you may need to measure the socket as well.

 How to Measure the Stem Size of Your Caster, Caster City

Threaded Stems

These stems feature a threaded exterior, much like a screw. When measuring a threaded stem, ensure that you are measuring the widest point across the threads. In this case, using a set of open-end wrenches can be particularly helpful.

How to Measure the Stem Size of Your Caster, Caster City

Remember, each stem type requires careful attention to ensure accurate measurement. Take the time to familiarize yourself with the specific stem you’re working with for the best results.

How to Measure the Stem Size: Tools Needed for Accurate Measurement

To get accurate measurements you need to have the right tools. Here’s a list of what you’ll need to get started.

  • A Caliper – A precise measuring tool that can give you the most accurate diameter of your stem.

  • A Ruler – In the absence of a caliper, a simple ruler can also serve as a measuring tool. Make sure your ruler has clear markings for fractions of an inch.

  • Open-End Wrenches – A set of these can help you check the diameter of the stem.

  • Drill Bit – If you’re measuring the socket where a grip neck stem fits, or need to measure the diameter of the hole that the stem goes into, a drill bit will come in handy.

  • Paper and Pencil – These will come into play when we explore a creative method of measurement using paper.

Remember, proper preparation leads to accurate measurements. 

How to Measure the Stem Size of Your Caster, Caster City

Step-by-Step Guide to Measuring Your Caster’s Stem Size

Let’s get started with the measurements. 

In this section, we explore three practical methods to measure the stem size, each requiring common household tools. 

Method #1: Using a ruler or a Caliper

Start by using a simple ruler for the measurement.

  • Place the ruler perpendicular to the length of the stem in the middle (not near the top of the ring). Most casters that have a grip ring stem have a 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.

  • The other possibility is the grip ring stem with a diameter of 3/8″. On a ruler, 3/8″ appears halfway between the 1/4″ and the 1/2″ marks. If you measure 3/8″ diameter for your grip ring stem, then 3/8″ diameter casters are the right choice for your needs.

If you have a caliper on hand, you can get a more precise measurement:

  • Open the jaws of the caliper and place it around the grip ring stem, below the ring, and towards the caster body.

  • Close the jaws around the stem and read the measurement.

If it measures .437 ± 0.01, you have a 7/16″ diameter. If it measures .375 ± 0.01, you have a 3/8″ diameter.

We currently have 7/16″ diameter stem rings in stock.

Method #2: Using Common Household Tool like a Wrench

Start by using an open-end wrench that fits over the stem. There should be a little “wiggle” between the wrench and the stem, indicating the size.

If you’re measuring the diameter of the hole that the stem goes into, use a drill bit in conjunction with the wrench for accuracy. Again, there should be a little wiggle but not much.

How to Measure the Stem Size of Your Caster, Caster CityHow to Measure the Stem Size of Your Caster, Caster City

Method #3: Using Paper to Determine Circumference

  • Cut a piece of paper about 2″ long.

  • Wrap the paper around the stem of your old caster, marking the paper where it overlaps the beginning edge.

  • Measure the paper length from the beginning edge to the mark that you made.

If you measured 1 3/8″, you need 7/16″ Diameter Stems.  

If you measured 1 3/16″, you need 3/8″ Diameter Stems.

How to Measure the Stem Size of Your Caster, Caster City

How to Measure the Stem Size of Your Caster, Caster City

How to Measure the Stem Size of Your Caster, Caster City

It’s important to keep in mind that while these methods are quite reliable, there may be slight variations due to the tools used or the precision of the measurement. Hence, it’s always a good idea to double-check the measurements to avoid any surprises down the line.

Visit Caster City’s stem casters for a range of casters suitable for different stem sizes.

Choosing the Right Caster for Your Furniture

Once you have accurately measured your caster’s stem size, the next step is selecting the right caster for your needs. Here are some factors you need to consider:

Weight Capacity

Every caster has a maximum weight it can comfortably and safely support. Consider the weight of your furniture and any additional weight it will carry. If the weight of your furniture is unknown, remove all items and try to weigh it or look up the weight online if it’s a manufactured piece.

Floor Type

Different casters are suited to different floor types. For example, soft rubber casters are ideal for hardwood floors as they won’t cause scratches.


Consider the caster’s intended use. If your furniture will be moved frequently, consider a caster with a high durability rating.

Aesthetic Appeal

If the caster will be visible, you might want to consider its appearance and how it fits in with your overall furniture design.

Troubleshooting Common Measurement Issues

Despite our best efforts, sometimes measurements might not go as planned. Here are a few common issues and solutions:

Measurement discrepancies

If you get different measurements using different tools or methods, it’s best to re-measure. Always follow the “cut once, measure twice” rule for accuracy.

Unclear ruler markings

Ensure you’re reading the ruler correctly. Remember, 7/16″ will measure slightly less than the 1/2″ mark, and 3/8″ appears halfway between the 1/4″ and the 1/2″ marks.

Paper slips while measuring

Make sure to hold the paper firmly while marking. A slip can lead to an incorrect circumference and consequently an inaccurate diameter.

FAQs About Caster Measurement and Installation

To further assist you in your caster replacement journey, we have compiled a list of frequently asked questions:

What if I don’t have a caliper or the exact measuring tools mentioned?

You can still measure the stem size using common household items. A simple ruler or even a piece of string can help determine the size. Remember, accuracy is crucial, so try to be as precise as possible.

Why does the diameter of the stem matter?

The stem diameter is key to ensuring your caster fits securely in its mount. An improper fit can cause instability, hinder mobility, and potentially damage your furniture.

Can I install a caster with a different stem size on my furniture?

Using a caster with a different stem size is not recommended. Even minor differences can lead to instability and premature wear on both the caster and the furniture.

Can I increase the size of the hole on my furniture to accommodate a bigger stem?

While possible, altering the furniture should be a last resort and done by a professional to avoid damaging the furniture.

Do I need to measure the stem size every time I replace the caster?

It’s advisable to recheck measurements each time. This can help avoid any errors or changes that might have occurred over time.

For further queries and personalized assistance, feel free to contact our support team at Caster City.

Additional Tips and Tricks for Caster Installation

Once you’ve selected your new caster and have your measurements at hand, you’re almost ready for the installation process. 

Here are some additional tips:

  • Ensure your furniture is stable before you begin the installation process. If possible, ask someone to help hold the furniture steady.

  • A rubber mallet can be useful for helping to install the caster into the hole without damaging the caster or the furniture.

  • After installation, gently test the furniture to ensure the casters are securely installed and that the furniture moves smoothly.

During the installation, it is crucial to ensure that all screws and fittings are tightened appropriately. Loose fittings can not only reduce the lifespan of the caster but also jeopardize the safety of the user.


Understanding the importance of caster sizes can spare you future frustrations with unstable furniture. So, the next time you set out to replace or fit new casters, measure twice and order once. 

Accurate measurement of your caster’s stem size is crucial to ensure the proper functioning and longevity of your furniture. With the right tools and methods, you can confidently measure your caster stem size. Remember, a well-fitted caster not only enhances the functionality of your furniture but also preserves the aesthetics of your space. 

At Caster City, we are committed to providing you with quality casters to suit your needs. Explore our product range and give your furniture the mobility it deserves!

Thank you for choosing Caster City, your trusted partner in quality and service.