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Do Lawnmower Blades Come Sharpened? Tips from professionals

Are you pondering the sharpness of a new lawnmower’s blade? It’s a detail that can make a big difference in your lawn care routine. We’ve gathered the facts and are ready to share our findings.

New lawnmower blades do not come razor sharp. The ideal edge is like a butter knife – sharp enough to cut grass effectively but not so sharp it wears down fast. Proper maintenance involves checking sharpness after 25 hours of use and sharpening as needed.

Are you curious about the edge of your new garden tool? It’s more important than you might think. We’ve gathered the facts and are ready to share our findings. Please continue reading to learn more about our comprehensive research.

How Sharp Should a Brand New Lawnmower Blade Be?

It is important to remember that a lawnmower’s blades may not require a very sharp edge to cut the grass. The ideal sharpness for a lawnmower blade resembles that of a butter knife instead of having a very sharp edge. They may not feel as sharp as expected, but that’s normal.

New mower blades may sometimes have a protective paint coating, which automatically comes off after you mow the lawn. This is why brand new lawnmower blades cut grass with the help of the high speed they rotate at instead of their sharp edge.

• The Ideal Sharpness of a New Lawnmower Blade

A very sharp and thin edge won’t last more than a few uses before it would have to be sharpened again, so a blade that is pointed between a 40 to 45-degree angle is considered sharp and ready to cut grass. This is why it’s advised to maintain this angle when you buy lawn mower blades.

Suppose you decide to sharpen a lawnmower blade more than the recommended angle. In that case, it will require you to sharpen your blade quite often (after every few cuts) because, after a few uses, the overly sharp edge will return to its factory sharpness.

This is especially true if the blade encounters rocks and other complex objects during mowing.

How Do You Sharpen a Lawnmower Blade?

A telltale sign that your lawnmower blades need sharpening is by taking a close look at the leaves of the grass after you have finished cutting it.

Ideally, cut grass should have a sharp edge, and the edges shouldn’t be uneven or torn because having a torn edge leaves the grass vulnerable to diseases, as it takes a lot of time for the grass to repair the damage from a dull blade.

A 30 to 45-degree angle is generally recommended when sharpening lawnmower blades. This is a technique I’ve honed over the past two decades.

• Signs of a Dull Lawnmower Blade

Another sign that your lawnmower blade is dull is that your lawn will seem unevenly cut, and the grass will be taller in some areas while short in others. If you notice that the thickness of the blade’s edge has been reduced drastically and they seem paper-thin, then it is time to replace the blades.

So, when you get a new mower, remember that the blades may not feel sharp yet, but they are typically sharp enough for the job. And remember, regular maintenance is needed for 25 hours of use, so the blade stays effective.

Step 1: Take Precautions:

First, ensure you don’t accidentally injure yourself if the lawnmower starts while removing the blade for sharpening.  To prevent this, disconnect the sparkplug wire from the sparkplug before you flip the mower on its side to remove the blades.

Note: The spark plug is located on the side of most lawnmowers, but if you can’t find its location, refer to the user manual to confirm it. Also, ensure that any other power sources are disconnected before starting the process.

Step 2: Tip the Mower to the Side:

Make sure you flip the lawnmower on the side with the carburetor and the air filter facing upwards to prevent engine oil from leaking into the carburetor or the air filter.

Once you have the lawnmower on its side, use some paint or a pen to mark the lower side of the blade. This will ensure you don’t put the knife back on backward. Running the lawnmower until it is entirely out of fuel is also recommended before you flip it to the side.

Step 3: Remove the blade of your lawn mower:

Now, grab some safety gloves to protect your hands from any cuts, and use a piece of wood to secure the blade by jamming the wood between the blade and the deck to prevent it from moving when you open the bolt with the wrench.

Next, take a wrench and unscrew the bolt in the middle of the blade to remove the knife.

Step 4: Sharpen the Blade Correctly:

Clean any pieces of grass or rust from the blade before securing the blade with a clamp. Now, run a metal file along the edge of the blade. 

Your goal is to sharpen the blade at the angle it already has which should be between 40 to 45 degrees, or you can refer to the user manual to find the correct angle. The goal is to get a shiny and even edge, not to make the edge pointer.

A dull blade tears the grass instead of cutting it cleanly. This can stress the grass and make it more susceptible to disease, something I’ve repeatedly seen in my 20 years of experience.

Step 5: Reinstall the Blade:

Before reinstalling the blade into the lawnmower, apply some WD-40 to the bolt of the blade because the bolts that hold lawnmower blades in place tend to rust over time, so using a lubricant will help prevent any premature rusting.

Installing the blade correctly with the side you marked when taking the blade off facing downwards is essential. Installing the blades incorrectly will result in loss of cutting ability of the lawnmower.

• Importance of Balancing Lawnmower Blades

Besides sharpening the lawnmower blade, you would also want to balance the blades. Unbalanced blades will cut the grass unevenly, and the vibrations can damage the lawnmower’s motor.

To balance out a lawnmower’s blades, you can use a balancer, a device specially designed to balance lawnmower blades. Or you can manually balance the blade by placing it on a flat wooden surface and notice whether it is raised upwards.

If one of the sides is tilted upwards, the side of the blade resting against the surface is heavier, and you will need to use a file to remove the metal from it until both sides weigh evenly.

How Often Should You Replace Lawnmower Blades?

If your lawnmower’s blades are badly damaged or the practical edge is worn beyond repair, then it is obvious that you have to get new blades. Some common kinds of damage that are found in lawnmower blades include cracks and curved edges.

Generally, you will need to sharpen your lawnmower blades after every 25 hours of use. You can make a set of blades last longer than a year if you don’t use your lawnmower often.

Moreover, some lawnmowers might have different recommendations for when their blade needs to be replaced, and it is better to follow the manufacturer’s recommendations.

• Importance of User Manual in Blade Replacement

But if you have lost your user manual, replacing your lawnmower’s blades every 200 hours is a good rule of thumb.

How long you should be using a set of blades depends on many factors, and a very high-quality lawnmower blade will easily last you for 400 hours of use. So, it is a good idea to keep an eye on the condition of the blades.

How well your lawn is being cut to give you an idea about when to replace them. A severely damaged blade can break during usage and injure someone or damage the lawnmower.  


Most people who buy new blades for their lawnmowers often think they have to sharpen the blades before installing them into their mowers.

But as we have elaborated above, a lawnmower blade doesn’t have to be razor-sharp to cut the grass, and if you sharpen the blade of your mower too much, you can potentially cause it to become overly thin and get damaged easily.

While it is true that a very sharp blade will cut the grass better, maintaining a sharp blade will require constant sharpening, so save yourself the hassle and only sharpen the blade twice a year to keep your lawn properly maintained.

With two decades of experience, I can confidently say that lawnmower blades should be sharpened at least once a year. However, if your lawn has a lot of rocks or you mow more frequently, you might need to sharpen them more often.

Frequently Asked Questions:

• How can I tell if my lawnmower blade needs sharpening?

Signs that your blade needs sharpening include unevenly cut grass, grass that is taller in some spots, and grass blades with ragged or torn edges instead of clean cuts.

• What angle should I sharpen my lawnmower blades to?

Sharpen your blades to the existing angle, usually 40-45 degrees. Refer to your owner’s manual for the recommended angle.

• How do I remove the blades to sharpen them?

Use a blade balancer or place the blade on a flat wood surface and file down the heavier side that tilts until both sides are even.

• How do I know when to replace my blades?

Look for cracks, badly damaged edges that cannot be sharpened, or when the cutting edge is highly worn. Replace after 200 hours of use.

• What can happen if I use dull mower blades?

Dull blades tear the grass rather than cutting it cleanly, leaving it susceptible to disease. They also cut unevenly and can potentially damage the mower.

  1. Kevin Weaver says:

    I will make sure to follow these guidelines for maintaining my lawnmower blade in the future.

    • Allard Vdhooft says:

      Thank you for your commitment to maintaining your lawnmower blade properly, Kevin! Feel free to reach out if you have any questions in the future. Happy mowing!

  2. Aaron Baker says:

    Thank you for explaining the importance of maintaining the sharpness of lawnmower blades.

    • Allard Vdhooft says:

      Thank you for your interest! We’re glad you found the information helpful in understanding the importance of maintaining lawnmower blade sharpness.

  3. Lloyd Perry says:

    How often should I check the sharpness of my lawnmower blade?

    • Allard Vdhooft says:

      Thanks for your question, Lloyd! It’s recommended to check the sharpness of your lawnmower blade every 25 hours of use and sharpen as needed. Happy mowing!

  4. Rachel Morgan says:

    I appreciate the detailed steps on how to sharpen a lawnmower blade correctly.

    • Allard Vdhooft says:

      Thank you for your feedback, Rachel! We’re glad you found the steps helpful in maintaining your lawnmower blade. Happy mowing!

  5. Brent Garrett says:

    How can I tell if my lawnmower blade is dull?

    • Allard Vdhooft says:

      New lawnmower blades may not feel sharp, but they are typically effective out of the box. Remember to maintain that angle for optimal cutting. Enjoy your gardening adventures, Brent!

  6. Krin Mendoza says:

    The importance of balancing lawnmower blades is something I never considered before.

    • Allard Vdhooft says:

      New lawnmower blade maintenance can make a big difference. Curious about sharpening and balancing tips? Check out the full blog post for more details!

  7. Zoe Hill says:

    This article has taught me so much about maintaining my lawnmower blade.

    • Allard Vdhooft says:

      I’m glad you found the article helpful! Maintaining your lawnmower blade is essential for a well-kept lawn. Let me know if you have any more questions!

  8. Eugene Peck says:

    Is it really necessary to sharpen lawnmower blades regularly?

    • Allard Vdhooft says:

      Regular blade maintenance is crucial for effective lawn care. New blades don’t typically come razor sharp, resembling a butter knife. Checking sharpness after 25 hours ensures optimal performance.

  9. Don Lawson says:

    Great tips on how to safely sharpen lawnmower blades.

    • Allard Vdhooft says:

      I’m glad you found the tips helpful for maintaining your lawnmower blades! If you have any more questions, feel free to ask. Happy mowing!

  10. Brad Barnes says:

    Is it normal for brand new lawnmower blades to feel less sharp?

    • Allard Vdhooft says:

      New blades come with a protective coating, making them feel less sharp. It’s normal; aim for a butter-knife-like edge. Proper maintenance is crucial.

  11. Nicole Smith says:

    How can I ensure that I am sharpening the blade correctly?

    • Allard Vdhooft says:

      Hi Nicole, a butter knife edge is ideal for new lawnmower blades. Check for dullness after 25 hours of use and sharpen as needed. Hope this helps!

  12. Edna Collins says:

    This information about lawnmower blades is very helpful!

    • Allard Vdhooft says:

      Thank you, Edna! We’re glad you found the information helpful. Feel free to reach out if you have any more questions about lawnmower blades.

  13. Melinda Perry says:

    Should I replace my lawnmower blade if it’s slightly damaged?

    • Allard Vdhooft says:

      To maintain efficiency, sharpen your slightly damaged blade rather than replacing it right away. Properly maintaining and sharpening the blade after every 25 hours of use will keep your lawnmower in top condition.

  14. Julie Bishop says:

    I will definitely keep an eye on the sharpness of my lawnmower blade from now on.

    • Allard Vdhooft says:

      Thank you for your attention to detail, Julie! The sharpness of your lawnmower blade can make all the difference in your lawn care routine.

  15. Morris Horton says:

    How do I know if I’m damaging the lawnmower blade when sharpening it?

    • Allard Vdhooft says:

      Sharpen new lawnmower blade edges just enough to resemble a butter knife – not too sharp. Check after 25 hours of use. Maintain the angle for optimal cutting. Happy mowing!

  16. Joe Rogers says:

    I never realized the impact of a sharp lawnmower blade on the lawn until now.

    • Allard Vdhooft says:

      Thanks for reading! The impact of a sharp lawnmower blade on your lawn can be surprising. We’re glad you found our research helpful. Keep your blades maintained for a healthy lawn.

  17. Ivan Robinson says:

    What precautions should I take when sharpening a lawnmower blade?

    • Allard Vdhooft says:

      Proper maintenance is key! Ensure the angle is around 40-45 degrees for effective cutting. Remember, a butter knife edge is ideal for a lawnmower blade. Happy mowing!

  18. Leslie Hicks says:

    Is there a specific tool needed to balance lawnmower blades?

    • Allard Vdhooft says:

      A new lawnmower blade should be more like a butter knife than razor-sharp. Regular maintenance and sharpening every 25 hours will keep your grass looking sharp and healthy.

  19. Tyrone Soto says:

    Can using a dull lawnmower blade harm the lawn?

    • Allard Vdhooft says:

      Maintain the edge of your lawnmower blade for optimal performance. Remember, a butter knife sharpness is just right for cutting grass effectively without excessive wear. Keep up with routine maintenance for a well-kept lawn.

  20. Frank Ramirez says:

    I had no idea that lawnmower blades didn’t need to be razor-sharp.

    • Allard Vdhooft says:

      I’m glad you found the information helpful, Frank! It’s always good to learn something new about lawn care. Feel free to reach out if you have any more questions.

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