Do I Need a Variable Speed Angle Grinder?

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Angle grinders are a toolbox essential due to their versatility of use for different purposes such as cutting, sanding, and even polishing surfaces. That said, no one-size-fits-all option will allow you to complete all these tasks using the same machine. 

These common power tools come in various types that differ in size and, perhaps more importantly, speed. Therefore, the type of angle grinder you choose will depend heavily on the work that you intend to use it for. In this article, we’ll discuss everything you need to know about angle grinder speeds and how to choose the perfect option for yourself, especially when it comes to variable speed angle grinders. So let’s jump right in!

Angle Grinder Speed

As you probably already know, angle grinders have a head that spins at extremely high speeds and can achieve anywhere from 2,000 to 13,000 revolutions per minute, depending on the size and power of the machine. 

There are two main reasons why using an angle grinder performing at the right speed is extremely important.

The first relates to the actual functionality of the machine. Using the wrong machine speed based on the job in question will directly impact how well the job will actually be completed. For example, if you are cutting through metal, you will need the angle grinder to move at a very high speed. Low speeds will impact your ability to cut through the hard surface and take forever to complete. 

The next, and more important reason, relates to your safety. Angle grinder discs are designed to handle a prescribed amount of force and pressure. Exceeding this can result in the disc breaking, and while spinning at high speeds, the pieces can fly in any direction, such as at the user’s face or body. 

Choosing the Correct Angle Grinder

Works requiring angle grinders are often conducted over an extended period and usually involve more than a single task. For example, when working with a piece of metal, the full process from start to finish may require you to cut, sand, and polish the metal to create the finished article. 

While each of these activities is being conducted on the same piece of metal, the performance requirements from your angle grinder will differ significantly through each process, as each step will require varying amounts of power and durability.

Variable vs. Fixed Speed Angle Grinders

Let’s take a look at the two common types of angle grinders side by side to see where their differences lie.

Variable speed angle grinders

These tools come with an additional function that allows the user to adjust the disc’s rotation speed. Variable speed angle grinders are much more versatile than their fixed speed counterparts; however, they also generally cost more too. 

Adjusting the speed means that one tool can be used for several tasks safely. Some high-end models come with paddle switches for even more control.

In short, if you plan to use your angle grinder for various tasks, then a variable angle grinder should be your go-to option, as the slightly higher investment will pay off over the long run. 

Fixed speed angle grinders

A fixed speed angle grinder generally spins at anywhere between 5,000 – 10,000 RPM; however, as we already mentioned, differing discs and surfaces require appropriate speeds. Therefore, these angle grinders will only be suitable for specific tasks. 

For example, an angle grinder that rotates at 7,500 RPM will easily cut through a hard metal pipe but will not be suitable if you’re planning to cut something softer, such as wood.

The major upside of these tools, though, is that they are much more affordable. If you only intend to use it for specific types of jobs on an ongoing basis, then you may have no need for the additional investment in a tool with various speed options, as a fixed-speed machine will more than suffice.

Do I Need a Variable Speed Angle Grinder? Grinder Power Tool

Angle Grinder Speed Recommendation

Below, we will provide an overview of the recommended speed to use your angle grinder based on the job that you are completing. 


Smaller discs should be set between 2,800 and 5,000 RPM when cutting or sanding wood, while larger discs should be set between 1,500 and 2,500 RPM.


For acrylics, small discs are required to spin between 1,000 and 1,500 RPM and larger discs between 500 and 800 RPM. 


To cut through stone, brick, or glass, a small disc will require between 1,500 and 2,000 RPM, while a large disc will suffice between 800 and 1,600 RPM. 


Stainless steel and cast iron will require significant speed and pressure. Small discs should be set between 4,800 and 9,000 RPM and large discs between 2,000 and 4,000 RPM.

Other Considerations

Whenever working with power tools, especially high-powered ones such as angle grinders, you should always ensure that you take the necessary precautions to make your task safe. 

Suitable PPE is always advised with even the smallest angle grinder before any undertaking. This includes face and eye shields to protect yourself against flying sparks and chips. At the same time, we suggest investing in suitable respiratory protection and protective gloves and footwear for larger ongoing projects. 

In addition to your personal accessories, you should also take the time to ensure that the accessories of your angle grinder match those required for the task at hand. This includes: 

  • Good quality discs 
  • Sufficient power supply 
  • An uncluttered work environment


Choosing a variable speed angle grinder provides significant advantages to the user, albeit at an increased cost. Deciding between a fixed and variable speed angle grinder relies mainly on the tool’s purpose and the likelihood of that purpose remaining consistent over time. 

Angle grinders are built to be versatile, and a variable speed option increases this level of versatility even further. Variable speed angle grinders are highly recommended for individuals that are looking for a power tool to use for a variety of jobs around the home or workshop for some time to come.

We hope that you now have the information you need to make an informed decision about whether you need a variable speed angle grinder.

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