Exactly How Sharp Should Lawn Mower Blades Be?

We are all familiar with lawnmowers, but have you ever wondered if your mower’s blades need to be sharpened? Maybe you’ve taken a look at them, and they don’t seem as sharp as you were expecting. Now you are left wondering, “how sharp should my lawnmower blades be?”

In general, you will want your lawnmower blade sharpened to about a 30-degree angle. The blades should be sharp enough to cut the grass without tearing or ripping it, but not so fine that the edge is razor-thin and easily damaged by the terrain or small debris in your lawn. You want your blade to be butter knife sharp, not razor sharp.

Your lawn mower blades do need proper care and maintenance to keep their edge honed and ready to cut your grass. There are differing opinions on how sharp you need to keep your blade. Mainly, this comes down to a balance between getting that good cut every time and the lengths you want to go to care for your grass.

However, there is a general rule that most homeowners can use to keep their mower cutting like new while not spending their weekends grinding away at their mower blades.

Butter-Knife Sharp not Razor Sharp

Can your blades be too sharp? Well, this depends on your type of grass, how well you are at avoiding obstacles with your mower, and the time and energy you have to invest in resharpening your blades.

Lawn enthusiasts have their own preferences for their mower blades. But, home and garden experts agree that for most people, the blades in your mower should be about as sharp as a butter knife, and an angle of about 30 degrees. You should be able to touch the edge without getting cut.

If your blades are super sharp, they will have a very fine edge that is more susceptible to rolling (a folding over of the blade edge). They will also be at increased risk for other types of damage. Your blades will dull faster and thus require sharpening more often.

More frequent sharpening means grinding away more metal from the edge. Increased grinding will decrease the lifespan of your blades, forcing you to spend money to replace them sooner.

This is especially true for those who do not have perfectly flat lawns or who may have more pebbles, weeds, tree roots, or otherwise woodsier terrain. Blades that are too sharp for this type of terrain will get damaged regularly and will need to be sharpened or even replaced if the damage is too extensive. Sharper is not always better!

How Often Do You Need to Sharpen?

Many factors will determine how often you need to sharpen your blades. You should check the edge for keenness and damage at that beginning of each season and after every eight to ten hours of use. You won’t need to sharpen them this often, but they should be checked regularly for bends, dents, and nicks that require fixing.

For most homeowners, sharpening once a year is usually enough to keep blades serviceable. This is best done at the beginning of the season as the elements can dull the edge as it sits in storage. If you have a considerable-sized yard or hit a lot of debris, your blade may require some maintenance halfway through the season as well.

During the lawn mowing season, there are many reasons that blades become dull through regular use. Of course, the act of cutting the grass slowly dulls the edge over time as do small particles of dirt that are flung against the blade as you mow. Other sources of dulling and damage include hitting small rocks, more massive clumps of soil, and other small debris in your lawn.

Inspect The Grass You’re Cutting

Aside from inspecting the blade, you should also look at the cut your mower is providing. If the grass edge looks torn instead of cleanly cut, you need to sharpen your blades. Grass that has uneven, torn edges has an increased risk of disease. This can damage your lawn, giving you dead or discolored patches that can be costly to repair or replace.

Dull blades that are not effectively cutting can lead to grass getting caught in your mower, which puts more strain on the motor. The health of your lawn depends, in part, on the health of your mower. Maintenance is key to keeping things alive and healthy!

Type of Terrain

The type of terrain you have is another consideration to be aware of. Flat even lawns with fewer rocks and other materials will lead to a longer-lasting edge.

However, uneven terrain with more tree branches or roots, stones or pebbles, weeds, and other materials lead to increased opportunities for things other than grass to come into contact with your blade. This will cause more damage. If your terrain is rough, you should check your blades more often as they will need more regular maintenance.

Mower Deck Height

You should also check the height of your mower’s deck. If you have it set very low, this will also increase the chance that you will hit mounds of dirt, tree roots, and rocks that will then bend, nick, and dull your lawn mower’s blade. Set the height of the carriage so that the blades are protected from most of the threats on your lawn.

Size of Lawn

The size of your lawn and how often you mow will also be a factor. A large yard that you mow often will lead to quicker dulling. Whereas small lawns or mowing less often will result in less wear and tear on the mower’s blades.

This is where the ten-hour rule comes in handy. If it takes you an hour to mow your lawn and you do it once a week, then you should check your blades every ten weeks. If you spend two hours mowing and you do it once a week, then you need to examine the blades every five weeks.

The Type of Blade Metal

The thickness and type of metal will also affect the regularity with which you need to sharpen the blade. Thicker, more durable metals will be more resilient and require less frequent maintenance. Whereas thinner or less durable metals will require more work to keep them in consummate grass cutting condition.

How to Sharpen?

If lawn maintenance is your Zen and you want complete control over your lawnmower, then you can sharpen the blades yourself. You will need steel wool to clean off any rust, a metal file for the quick jobs, an angle or belt grinder for the bigger ones, and a blade balancer. There are a lot of great sites out there with step-by-step How To’s. You can check one out here.

However, if that sounds like too much time and money to invest in your little push mower and a weekend chore, you can always take your lawnmower to a shop. Most shops that sell lawnmowers also have the equipment to sharpen their blades.

You can also benefit from their expertise on how to best repair the blade, they know how to sharpen it correctly, how to balance it, and how to check for other damage. They will also know whether the blade can be repaired or whether it should be replaced. The whole process should only take a trained staff member about 20 minutes to complete.


In general, a butter-knife-sharp edge is where your mower’s blades need to be. Keeping your blades sharper can lead to increased damage and require more frequent maintenance. This will not just take more of your time but also more of your cash.

How often you need to sharpen your blades will depend on your lawn and mowing schedule, but you should sharpen them once to twice a year, at least.

You should also check your blades roughly every ten hours, and if you think they require care, take them to a shop for professional upkeep, which will keep you and your lawn safe and healthy!

Jeremy Hoxie

I'm Jeremy and I'm the golden retriever raising, craft beer drinking, guy in the neighborhood who spends too much time on his lawn. Fueled by my passion for understanding the nuances of lawn care, I am eager to both build onto my experience maintaining lawns over the years and testing new things while on the hunt for the perfect lawn!

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