Are Lawnmower Blades Supposed to Be Sharp?

There is nothing quite like the smell, feel, and look of fresh-cut grass. Mowing the lawn is something done by most people weekly, as the weather and seasons permit.

While mowing the lawn is a rather simple task, the maintenance of your machine needs to be thorough and frequent. This maintenance includes the blades of the mower.

Lawnmower blades should be sharp, but not razor-sharp. If the blades are razor-sharp, they will become dull quickly. However, if the blade is not sharp enough, the grass will be torn from the ground rather than being cut.  

In this article, you will learn how sharp your lawnmower blades need to be, the proper tools to use, and what to look for when determining if the blades need to be sharpened or possibly replaced. 

Exactly How Sharp Should the Blades Be?

When you consider the sharpness of your mower blades, you need to be careful that you do not make them too sharp. 

A good rule of thumb is to focus on the sharpness of the blades at the time of purchase. When the lawnmower is assembled at the factory, the blades are ready to be used, and no sharpening is necessary. 

There is not a specific formula when it comes to determining if the blades are sharp enough. The best way to make the determination is by carefully observing your lawn. 

If you notice the grass being pulled instead of cut, this is an indicator the blades are not sharp enough. 

How to Sharpen Lawnmower Blades

If you have determined the blades of your lawnmower need to be sharpened, you are in luck because there aren’t many things required to do the job well. 

To sharpen your blades, you will need the proper tools. It is essential to follow the correct steps to ensure your safety and to protect the life of your mower blades. 

Here are the proper steps to follow when it comes to removing the blade from your mower:

  • Carefully position the mower so you can safely remove the blades. If you are sharpening the blades of a riding mower, you will need to make sure it is held up securely, so it does not fall on you during the removal process. 
  • Using the proper tools, you will need to remove the bolt that is holding the blade in place. Secure the blade while you are attempting to remove the nut, so it does not move around. 
  • When the bolt has been removed, you can carefully pull the blade off, making a note of the direction it needs to be placed back onto the mower. 

When you sharpen the blade of your mower, it pays dividends to take the necessary time and follow these steps to do it correctly:

  • Secure the blade into a vise.
  • Use a hand file to sharpen the edge of the blade to about the sharpness of a butter knife.

Sharpening a mower blade is not a challenging task if you take time and use the proper tools. Here are the tools you will need to have on hand:


This tool typically attaches to a workbench or table.  It is used to hold items you are working on securely in place with a pressure that is adjusted with a hand crank.

There are many different sizes that you can get; however, a small vise will likely serve the purpose of holding a mower blade securely in place. 

If you don’t have a vise at home, you can buy one on Amazon. The Yost LV-4 Home Vise is perfect for this purpose.

Hand file

A hand file is the best tool to use when you need to sharpen a mower blade. It may seem that an electric grinder would make for faster work. However, over-sharpening the blade is a real possibility. 

Hand files can be bought at most local hardware stores, but you can also buy them online.

My recommendation would be REXBETI 16Pcs Premium file set – it has 16 files that all come in different shapes and/or sizes, making it ideal for blade sharpening as well as a wide range of other tasks. You can buy it on Amazon.

Socket wrench

The easiest way to remove the bolt that holds the blade in place will be with a socket wrench. All bolts are different sizes, so it would be wise to have a set of sockets that you can change in and out. 

A good example of this tool would be the EPAuto 1/4-Inch & 3/8-Inch Drive Socket Set. It has 40 different sockets, so you can be sure it has one for most bolts you will encounter. You can buy it on Amazon.


Whenever you are working with material that can be sharp, you need to take the proper precautions to protect yourself. Gloves will help protect your hands as you remove and sharpen the blades. 

The type of protective gloves you use mostly comes down to preference, but if you are undecided, I’d recommend a pair of Ironclad General Utility Work Gloves. You can buy them on Amazon.

While it is recommended to have gloves to protect yourself, it is entirely possible to change the blade on the mower without them if you use caution.

How Long Does It Take to Sharpen a Blade?

The most time-consuming part of the sharpening process will be removing the blade from the mower deck. Once the blade is off the mower, it will likely take 10-12 minutes to complete the sharpening process. 

When Should You Replace the Blades?

There are times when mower blades cannot be sharpened and need to be replaced. When determining if a mower blade needs to be replaced, you want to check for the following things:

  • If the cutting edge of the blade is extremely thin, you may need to consider replacing the blade.
  • If there are dents or nicks in the blade, it may be impossible to sharpen it, and it will need to be replaced.
  • If you have sharpened the blade many times, it may be time for a replacement. 

Challenges You May Face

While the removal and sharpening of the blade are quite straightforward, there is always a chance that you could run into some challenges. Here are some of the challenges you may face as well as their simple solutions:

The bolt won’t come loose 

Because the bolt is exposed to the dampness of the grass, there is a chance that it can build up rust, not to mention the bolt is securely fastened to allow the mower to perform well. 

Quick fix: If the bolt is difficult to loosen, you need to make sure the blade is not able to move, this will protect your hands and make the bolt easier to loosen.

Once the blade is blocked, you can also spray a lubricant like WD-40 on the bolt. Often, this will penetrate the rust and allow the bolt to be loosened. 

No time to sharpen the blade

Perhaps you find yourself in a time pinch and do not have time to sharpen a new blade. Whatever you do, do not try to sharpen the blade while it is on the mower because it will not turn out well. 

Quick fix: To cut down on the time required to sharpen the mower blade, it is helpful to have an already sharpened blade waiting to replace the dull blade with. You can still sharpen your old blade later.

Balancing the blade

Another challenge that you may face involves balancing the blade of your mower. Two edges need to be sharpened.

It can be difficult to sharpen them evenly, so you must take time to balance the blade.

Quick Fix: To balance the blade, attach a nail or screw to the wall and hang the blade on it. If the blade is balanced, it will not fall to either side.

If the blade is not balanced, it will not hang evenly on the nail. You may need to adjust the blade accordingly by sharpening to ensure it is balanced. 

Final Thoughts

Keeping the blade of your mower sharpened is extremely important to ensure you can maintain your lawn appropriately. While it is not a complicated process, the proper tools and know-how will serve you well as you begin the process.

Remember, the blade should be no sharper than a butter knife, and it will likely need to be replaced after a season or two.

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!

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