Shore Hardness vs. Durometer: Complete Explanation

Getting the physical properties of your materials right is a huge factor in product performance and success. For anyone making physical products, one of the biggest deals is nailing how hard or soft your plastics and rubbers are. This is where you hear people throw around words like “Shore hardness” and “durometer.”

Professionals often use these terms interchangeably, but they refer to two distinct aspects of the same test. And we’re going to clear up that whole mix-up right now. Getting this straight is one of those little things that stops big, expensive problems before they start.

What is Shore Hardness?

Shore hardness is the standardized scale used to put a number on a material's resistance to being indented. It was developed by Albert Ferdinand Shore in the 1920s, and his method was so spot-on that it’s still the gold standard.

Think of it like this: a high Shore hardness number means the material is tough as nails and won't let an indenter make much of a dent. A low number means the material is more of a softy, with a ton of give. It’s the secret language everyone uses to talk about texture and toughness without guessing.

A Closer Look at the Shore Hardness Scales

Different material types require different testing approaches, which is why the Shore system uses several distinct scales. We've found that choosing the correct scale from the start is essential for getting a meaningful measurement and avoiding specification issues down the line.

It's also useful to know that the scales have some overlap. For example, a hard 95 on the Shore A scale is roughly equivalent to a softer 50 on the Shore D scale. That's a detail that can really bite you if you’re not paying attention.

Related article: Durometer Hardness Scale: A Complete Guide

What is a Durometer?

The durometer is the physical instrument used to perform the test and get a Shore hardness reading. This is the source of the common confusion in the durometer vs shore hardness discussion.

It has a little poker that sticks out, which you press firmly against your material. How deep that poker sinks is what gives you the reading. You’ll see the number pop up (typically from 0 to 100), on either an old-school analog dial or a crisp digital screen. 

Read more: What is Durometer? All You Need to Know

Durometer vs. Shore Hardness: The Key Differences Summarized

So, what’s the big difference between durometer vs shore? While the terms are used loosely in conversation, using precise language in any technical setting is always the better practice.

Here’s the simplest way to think about it:

• Shore Hardness is the score you get. The number itself, like "70A."

• A Durometer is the instrument you use to get that score.

Here’s a little cheat sheet we made to make it stick:

How to Ensure Accurate Readings

Getting a number you can actually trust comes down to good technique. Anyone can get a reading, but professionals get a reliable one. 

The golden rules are straightforward: test on a completely flat surface, ensure your material has sufficient thickness, and take your reading well away from any edge. The real pro move is to average three to five readings to get a number that truly represents the material. 

Read our complete guide on this topic here → How to Use a Durometer in a Few Easy Steps

The Qualitest Solution

The whole shore hardness vs. durometer thing is mostly about people using the words loosely. We believe precision in language prevents errors. 

The "durometer" is the testing tool, and "Shore hardness" is the value it produces. The most important information is always the number and its corresponding scale (like 75D). That’s how you make sure your part has the perfect amount of squish or stiffness.

At Qualitest, we have extensive experience helping clients with their material testing needs. We supply a full range of high-quality, cost-effective materials and the high-performance analog and digital durometers required to verify them. 

If you have questions about material hardness or need assistance selecting the right instrument for your application, our expert team is here to help. Contact us today to learn how our solutions can support your quality and production goals.