How Often Should Lawn Mower Blades Be Changed? (+Mistakes to avoid)

For maintaining a proper, clean, and attractive lawn, it is important to look after the blades of your lawn mower after using it each time. Regular inspection can also maintain the proper and healthy growth of your grass.

You should sharpen quickly as soon as you notice that your lawnmower blades have turned blunt. But if you can’t repair the damage, it should be replaced with a new one. But how often should you change mower blades?

Generally, an average homeowner should replace their land mowers blade annually. Depending on the lawn mower’s usage, the blades can last for 200-250 hours, after which it needs a replacement. Sharpening the blade after every 25 hours of usage will prolong the life of the blades.

This article will help you know how often you should change your lawnmower blades and what mistakes to avoid.

Lawn mower blade removal

When do you need to change your mower blade?

When your lawn mower blades have been damaged or sharpened frequently, it is important to either change them with a set of used blades in good condition or use new sets of blades instead. 

Lawn mower blades can get blunt, shabby, and damaged when hit by wood chips or rocks. 

Also, if you have not changed the blades for too long and sharpened them many times, you should change them to avoid further damage to your lawnmower. 

Let’s discuss a few signs to determine when your lawnmower blades need to be sharpened or changed.

Uneven grass length

One of the things you will notice is that your lawn may not look well-maintained and clean as it usually does.

Blunt blades do not provide a finished and clean cut. 

You may notice irregular patches, or you have to go over them again and again before it actually cuts the grass. 

This happens because a blunt blade requires much effort to mow your lawn. On the other hand, if the blade is sharp, you will notice that you can easily cut the grass with equal height. 

If you observe that cutting the grass takes more time and effort than normal, it is the perfect sign that your mower blade needs to be replaced or sharpened.

Tear or messy cut

You can inspect the blade condition by looking at how your lawn grass looks after mowing. 

During the healthy cut, each grass gives a clean look without any messy cut. 

Suppose you will ignore your lawnmower blade condition and continue using it. 

In that case, it can easily damage the health of your grass, causing it to decrease its charm and green color, and can even invite various grass diseases and infections. 

Also, if you notice the grass tips are torn, and the cut is rough, you may need to switch blades. 

If you see that the lawnmower blades look jagged instead of sharp and cleanly cut, then it’s time to change or sharpen them before anything serious happens.

Blade condition

Lawn mower blade cleaning

Another sign to know whether your lawnmower needs replacement or not is by inspecting the blade itself. 

Usually, you need to keep sharpening the blade to make a clean cut. 

But if you notice the blade is cracked or hollow, you may need to change it. 

You should also check the thickness of your lawnmower blade because it gets thinner as time goes by. 

It happens because of continuous sharpening and mowing in the sand and dirt with huge rocks. 

It can make the metal thinner and weaker over time.

It is better to inspect the condition and change it immediately if it has a poor condition. 

Otherwise, the blade can break in the middle of the mowing, which can be very harmful as it may injure anyone standing close to it. 

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How often should the lawn mower be changed? (Reasons)

Look at the blade and check whether it is broken, blunt, weakened, or damaged completely. 

In that situation, the blades need to be changed. 

A usual lawnmower blade lasts up to 200-250 hours of run time, depending on the quality and mowing power. 

Then it needs to be replaced.

If your lawn has lots of hard objects like sticks and stones, then there is a high chance that the blades can get damaged quickly.

The highest quality blades can last up to 400 hours of run time. 

Also, as soon as you notice that the blades have come in contact with a hard object, you should immediately check it.

How often you should change the blades depends on some factors:-

  • Poor cut– If you notice that the lawn is looking untidy and the cut has not made any difference in the grass after mowing, then the blade needs to be changed.
  • Consistency– Consistency plays an important role in how often you should change the blade. The more you mow the lawn and are consistent about it, the more blades need to be changed frequently.
  • Quality – How often you change the blade depends on the quality. If the blade’s quality is poor, it will get damaged more quickly, and the blades need to be changed more often.

Also read: Is It Better To Sharpen Or Replace Mower Blade?

How to change a lawnmower blade?

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Now let’s discuss how you can change your lawnmower blade. 

You have to follow the steps given below:-

Detach the ignition wire and empty the gas 

The first step is to detach the ignition wire from the spark plug. 

But if your lawnmower has no cord or it’s automatic, remove the battery from it.

It is important because the engine can accidentally start while working, which is very risky. 

Also, empty the gas from the tank to avoid spilling fuel while replacing the blades. 

Tilt the mower

Tilt the mower on one side to uncover the bolt that keeps the blade attached to the mower. 

Before doing this, you should stop the blade from rotating. 

Grab a pair of locking pliers and close them to the side of the lawnmower deck. 

Now when your blade goes to rotate, it will hit the locking pliers, and it will not be able to turn. 

You can also use a wooden block.

Then use a ratchet to remove the bolt. 

Avoid using a wrench, as it doesn’t have that much leverage.

Remove the blade

You should pull the blade right off the mower as soon as you remove the bolt. 

But be careful about the washers and other useful objects that keep the blade in one place.

Remember the position of the blade.

You should carefully remember which blade’s side faces downward. 

It is important because you can compare the edges and ensure the cutting edges match as they were before.

When you reinstall the new blade, it will fit exactly the way the old one does.

Fix the new blade

Fix the new blade in the correct direction. 

Try to line up the blade exactly like before, then set up the washers and nuts. 

While mounting the new blade, ensure you don’t over-tighten the nuts; otherwise, it can cause vibrations.

Also, before mounting, you should always check that the length of the blade is the same as the old one. 

You should always wear gloves before doing such tasks to avoid any injury.

Examine the blade

Examine the blade and see whether it is working properly or not. 

Also, there should be no vibrations. 

Remove objects holding the mower in one direction and wait for at least 45- 60 minutes to give some time to the motor so that the oil will return to the engine. 

Reconnect the spark plug

Fill the gas tank again and then reconnect the spark plug wire. 

Then do a quick scan before mowing.

Inspect the air filter to avoid saturation in the foam filter because of oil. 

After that, your lawn mower is ready to run efficiently. 

Why not sharpen instead of replacing?

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One of the biggest advantages of sharpening is that you can easily save money and time without any extra expense on a new blade. 

You can sharpen your existing blade with the help of a few pieces of equipment.

  1. Gloves
  2. Safety glasses
  3. Flat metal file
  4. A vice 

If you already have all this equipment in your house, you can simply sharpen the blade without changing it often. 

Once the blade is sharpened, it can work fine, but the main question is should you sharpen instead of replacing it? 

It completely depends on the condition of your lawnmower blade.

You can sharpen your normal blade as per the schedule until and unless it is suddenly damaged. 

For example- If the lawn mower suddenly gets hit by a huge rock, then sharpening the blade won’t help; instead, complete replacement is required. 

Also, sharpening can degrade the blade quality, which will not make it a long-lasting like-new blade. 

Sharpening is only suitable for a blade that is not broken or bent, but it’s best to replace it entirely.

Also read: 9 Ways To Sharpen A Lawnmower Blade Without Removing It (+Mistakes To Avoid)

How often should you sharpen?

Generally, you should sharpen the lawnmower blade every 25 hours of run time once a week. 

But most house owners think sharpening after every 25 hours of run time is excessive. 

But if you are mowing your garden every week and the machine hits at least 20 to 25 hours of cutting time, then the sharpness of the blade automatically degrades, so it is necessary to sharpen it. 

Always check the lawn condition after mowing to determine the blade sharpness and do it according to that.

How to make lawn mower blades last longer?

Lawn mower fixing blade

Usually, owners change their lawnmower blades often due to some damage. 

But there are some tips to make it last longer. Let’s discuss the following:-

  • Before cutting the grass with a mower, you should always ensure there are no sticks, huge rocks or stones, plastics, or toys in the lawn so that the blade doesn’t make any contact with them to avoid a sudden accident. If you ignore such objects in your lawn, they can not only interrupt the mowing process but also damage the blade, and you will need to replace it frequently. 
  • You should sharpen the blade after every 20 to 25 hours of runtime. It can make the blade long-lasting, and it will also not cause any damage to the edge. Please don’t go for a replacement first before giving it a try to sharpen. 
  • You should also know how to sharpen the blade appropriately. You need to have proper knowledge about it before attempting it. If you don’t know how to sharpen it correctly, the blade may get damaged, reducing its overall lifespan. 

Mistakes to avoid while replacing the blade

Let’s see common mistakes most people make while changing the lawnmower blade.

  • Sharpening too frequently- Most owners think that sharpening lawnmower blades many times can increase their lifespan, which is wrong. On the other hand, sharpening too frequently can weaken the blades and decrease efficiency.
  • Not Emptying the fuel- People often forget to empty the fuel from the tank before changing the blade. It can do a lot of fuel waste, as tilting the mower is necessary to change the blades. 
  • Incorrect direction- Fixing the blade in the incorrect direction is one of the common mistakes. People may get confused. 
  • No experience- It’s difficult to replace the blade without any experience. It’s better to get some knowledge and learn about this before making any mistake that can cause damage to the mower or lawn. 

Final words

Once you know how often to change the lawn mower blade, you don’t have to struggle anymore to mow the lawn. 

Look after all the factors that affect the condition of the blade and then change it accordingly. 

Sharpening can also do the trick sometimes, but it’s better to replace the blade entirely when completely damaged. 

The most important thing is to look after the blade condition often to know when to change it. 

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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