Is It Better To Sharpen Or Replace Mower Blade?

It is important to maintain sharpened mower blades to keep the lawn healthy. There are high chances that your lawnmower blades can get blunt easily due to a lack of maintenance.

Generally, it depends on the condition of the blade. If your mower blade has only turned blunt, you can sharpen it without any problem. But if the blade condition has not improved even after sharpening and it is completely broken or bent, then you need to replace it with a new one.

This article will help you to decide whether your mower blade needs replacement or sharpening. Let’s read further to get into details. 

Lawn mower fixing blade

Sharpening vs. Replacing (Which is better?)

If the condition of the lawnmower blade has become poor, it needs to be fixed as quickly as possible. 

If you notice the blade tearing the grass instead of giving a proper clean cut, it’s time to either sharpen or replace the blade. 

But which is better? 

It depends on how much your blade is damaged. 

If your blade has just turned dull, then sharpening can fix the problem. 

But if the blade is twisted and broken, complete replacement is the only option to fix this issue. 

Also, when the quality of the blade degrades due to frequent sharpening, it’s better to replace it with a new one.

Signs to know when the blade needs to be sharpened or replaced

Before you decide which is better, you must understand when the mower blade needs sharpening or replacing. Here are a few signs to find out:-

1. Uneven cut of the grass

If your grass seems to have uneven cuts after mowing, it means the blade in your mower is blunt or damaged. 

Normally, a sharp lawnmower blade cuts the grass evenly at the same height, and you will not see any uneven and messy cuts. 

However, if you mow the lawn with a damaged blade, you must push the lawnmower in the same area many times to get satisfactory results. 

That’s when you understand the blades should either be sharpened or replaced.

2. Tearing of the grass

Look at the grass to see if the tips are torn down improperly instead of giving a fresh, clean cut. 

This signifies that the blades are destroyed, which is the reason behind the nasty cut. 

If the grass is in poor condition, sharpen or replace it as soon as possible to promote healthy growth. 

3. Lawn turning brown

If you notice that the blades are not cutting the grass, but instead of that it is tearing them, then the lawn can eventually turn brown.

Tearing the grass can stress them, which can also invite various pests and diseases, resulting in brown patches in your lawn. 

As soon as you notice dry and brown patches, it means the blades need sharpening or replacing. 

When does the lawnmower blade need to be sharpened?

Lawn mower blade cleaning

Here are a few reasons with the help of which you can understand when the blade is dull and needs sharpening.

  • When the blade is only blunt, not broken. 
  • If there is no frequent sharpening for a longer period.
  • To save a lot of time
  • For maintaining budget

Let’s discuss each point in detail:

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Reasons to sharpen your lawnmower blade instead of replacing

Here are the reasons to know why sharpening is suitable in some cases:

1. Blunt blade

If the blade has only turned blunt but has not been broken, then replacement is not required; only sharpening can fix this problem.

Blades can get dull with frequent mowing, so you can simply sharpen them instead of replacing it to maintain your blade condition.

2. Not sharpening the blade for a longer period

You should always look after the blade frequently to check its condition. 

If you refuse to do that and don’t sharpen the blade from time to time, you can see an uneven cut on your lawn. 

If you haven’t sharpened the lawnmower blade for too long, then make sure you do it. 

You need to sharpen the blade often to maintain the blade. 

3. To save a lot of time

If you hardly get any free time but want to maintain a healthy lawn, it is better to sharpen the blade instead of replacing it. 

Removing the entire blade from the mower and replacing it with a new one is very complicated and time-consuming. 

If you want to save time, you can simply sharpen the blade without removing it from the mower.

4. To maintain budget

If you don’t want to spend your money replacing each time a blade gets blunt, then sharpening is the most cost-efficient process to fix this problem. 

Replacing the blade is more costly than sharpening, so it is more suitable when the budget is low. 

How to sharpen a lawnmower blade?

  • First, drain the fuel and then seal the gas tank properly. 
  • Then, disconnect the power cord to avoid a sudden accident. 
  • Turn the lawnmower over to one side and support it with the help of wood. 
  • Block the blade movement by locking pliers to the side of the lawnmower deck.
  • If you want to sharpen the blade without removing it, then start grinding the blade with the help of tools like drill blades, regular files, electric grinders, honing steel, etc. 
  • Make sure to sharpen the blade at a 45 degrees angle. 
  • Always grind only in one particular direction. Also, remove the same quantity of material from both sides of the blade to maintain balance. 
  • If you want to sharpen the blade by removing it, remove the bolt, pull it out from the mower, and grind it.

Do new lawnmower blades need sharpening?

Some brands have a little coat of paint, so it is important to sharpen the blade before using it. 

But most new mower blades don’t need sharpening since they are already in good condition, so there is no need to waste time. 

Once you get new blades, you can install them immediately and use them without any problem.  

When does the lawnmower blade need to be replaced?

There are a few reasons why a lawnmower needs a complete replacement of the blade:

  • When the blade is twisted, broken, or damaged completely.
  • When the blade is blunt, even after sharpening. 
  • If you haven’t changed the blade for a few years. 
  • If the blade condition is extremely bad.

Let’s read further to know about each reason in detail. 

Reasons to replace your lawnmower blades

Here are the reasons given below which indicate that it is time to change the mower blade:

1. Twisted, broken, or damaged

It is common for the mower blade to twist or damage if you mistakenly mow over hard objects like debris and rock. 

If the blade is twisted, it becomes imbalanced and a huge threat to you and the lawnmower. 

Replacing damaged blades can save you from sudden accidents and ensure a healthy lawn cut.

Here are a few signs to know if the mower blade is bent:

  • The machine gets rough while mowing.
  • Weird noises come when you start the engine. 
  • If your lawnmower suddenly stops moving. 

2. Blade is blunt even after sharpening

 If the lawnmower blade is still blunt even after sharpening, then the only option is to replace the blade. 

A blunt blade creates an unhealthy lawn because of the ripped grass, making it very difficult to get even cuts. 

Sharpening can often weaken the mower blades, causing serious damage to the lawn and the machine itself. 

So, replacing the blade is required. 

Also, frequent sharpening can degrade the blade quality, so make sure sharpening is not always recommended. 

3. If the blade is not changed for more than a few years

Normally, the blade needs to be changed after every few years. 

Also, it depends on how often you use your lawnmower.

If you have a large lawn and you mow the lawn quite often, then you need to change the blade each year. 

But if you have a small lawn and mow it less frequently with good maintenance and less damage, you can use it for more years and then replace it. 

4. Blade condition is poor

If the blade is rusted, chipped, or extremely thin, then it will not be able to cut the grass evenly. 

Due to uneven and abnormal cuts, your lawn can turn brown.

The blade becomes rusty because of corrosion due to moisture in the soil.

 If the metal has become extremely thin with rust, then there is no option other than replacing it. 

Thin metals are impossible to sharpen, and you can even break them. 

How to replace a lawnmower blade?

  • First, detach the plug wire so the machine will not start in the middle of the replacement. 
  • Then, drain out the fuel from the gas tank, or you can also seal it properly to avoid leakage. 
  • Turn the lawnmower to one side, then provide support with wood pieces to stay stable and not fall accidentally.
  • Then, stop the movement of the blade with the help of locking pliers. 
  • Remove the bolt with the help of a ratchet. Then pull the blade from the mower. 
  • Be careful that you know which side of the blade faces downward so that you can reinstall the blade exactly in the same way as earlier. 
  • Then choose a blade the same length, just like the old one.
  • Then grab your new blade and fix it. Ensure you don’t over-tighten the blade; otherwise, it can cause vibrations. 
  • After replacing, unseal the gas tank, refill the fuel again and wait for at least 40-60 minutes before you start the engine again. 
  • Then reconnect the spark plug. Now, your lawnmower is ready to go. 

Mistakes to avoid while sharpening or replacing the blade

Let’s discuss some mistakes which you should avoid:-

  • Not knowing whether to sharpen or replace: Sometimes, people replace the blade too soon when you can just sharpen it. The lawnmower blade needs replacement after 2-3 seasons until and unless it is damaged for some reason. Make sure you know the difference between when to replace and sharpen. 
  • Sharpening or replacing without draining out the fuel: Forgetting to empty the fuel from the gas tank is very common. People often make this mistake and end up wasting a lot of fuel. Make sure to drain out the fuel and seal the tank properly. 
  • Sharpening too often: People think sharpening more often can increase the blade’s lifespan, which is not true. On the other side, it can make the blade weaker and thinner, which can decrease efficiency. So, avoid doing this.
  • Replacing it in the wrong direction: Most owners get confused while replacing the new blade. They often make mistakes by fixing them in the wrong direction. Make sure you know the correct direction of the blade before finally placing it. 
  • Ignoring weird noises and vibrations: If you have sharpened or replaced the lawnmower blade and some weird noises and vibrations are coming from the engine, then it’s not normal, and you should never ignore it. It mostly happens when you over-tighten the blade or the blade is imbalanced. Try to fix it rather than ignoring such issues. 
  • Not having experience: It’s hard to sharpen or replace the blade without experience. Always read some instructions and take advice from the experts before attempting any mistake which can cause damage. 

How often to sharpen or replace the lawnmower blade?

In case of sharpening

It depends on how much you have used your lawnmower. 

The more the machine is used, the more often it needs sharpening. 

If your lawnmower has run for 20-25 hours, you need to sharpen the blade to improve its efficiency. 

Also, if there is a huge lawn and you mow the lawn for 1 hour, then the blades need sharpening after 20 uses. 

But if the lawn is small, then sharpen it after 40 uses. 

In case of replacing

Usually, a normal lawnmower blade lasts up to 100 to 200 hours of run time. 

When the machine has accomplished these hours, it needs to be replaced. 

But if the blade is of the highest quality, it may last up to 400 hours of run time.

Otherwise, replacement also depends on the condition of the lawn. 

If the lawn has harder objects like rocks, stones, and sticks, it can damage the blade before its expiration, and you need to replace it more quickly. 

Always look after the mower blade to check whether it needs any change, as it can get damaged anytime. 

Final words

The lawnmower blade should always be in good condition for maintaining a healthy lawn. 

If you notice uneven grass, brown patches, or torn grass, the blade either needs replacement or sharpening. 

But the most important thing is knowing the difference between sharpening and replacing and which is better in what situations. 

Inspect the blade properly and decide which will be suitable to do. 

Reference: Lawn Mower Technology, Lawn Mower SafetyLawn MowingLawn CareMowing your lawn.


Hello everyone, My name is Richa and I am here to make you a better gardener by creating an in-depth and helpful resource for all the fellow gardeners out there. If I could help even a few people understand their plants better then I call it a success for my efforts.

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