How sharp should mower blades be is a pertinent question about this lawn care machine.

Distinct Edges of Mower Blades

Cutting grass with oversharpened and dull blades will damage it and make it prone to disease. This all-encompassing guide will discuss the ideal sharpness for all lawnmowers.

You will also learn how to sharpen blades by yourself step-by-step.

How Sharp Should Mower Blades Be To Cut Well?

Mower bales to cut well should have the edge sharpened at an angle of 30 degrees is the ideal sharpness for a lawn mower blade. They should be distinctly sharp as a kitchen knife when a finger is run gently along its cutting end, but not as a razor blade. 

It is a misconception that lawnmower blades should be razor-sharp to cut grass faster and more efficiently. Sure, a blade that is sharpened to razor-edge thickness will no doubt be able to cut grass much more easily without ripping or tearing it. You will also get the job completed in a short amount of time. 

However, razor-sharp blade edges are extremely vulnerable and break easily after coming in contact with any obstacle or debris during grass cutting, because when they are as sharp as a razor, then it will be hard for the machine to do its job properly and accurately. That is why a simple kitchen knife’s sharp edges are the best because they provide efficient cutting and are strong enough to withstand unwanted obstacles. 

In order to reach this level of sharpness, the angle of the cutting edge should be 30 degrees to the rest of the blade. It shouldn’t get cut when a finger is run across this edge. Another reason 30 degrees is the ideal sharpness is that the blade doesn’t get dull as often and can last a fairly decent time; moreover, you won’t even be frustrated to think how it is going to be accomplishing such a task, due to the excess time it will take.

With blades sharpened at steeper angles, the blade dulls faster and experiences a rolling phenomenon. Rolling is basically when the cutting edge gets folded from pressure. If the lawn in question is made of uneven terrain and filled with tree roots, pebbles, and stones, these blades will not last much longer.

How Often Do Blades Need Sharpening?

The lawn mower blades need sharpening is a notion which would depend on how much they are being used. Nevertheless, you need to check up on the sharpness of the mower blades after every 20 to 25 hours of use.

What you should do is check how sharp the blade is at the beginning of each grass season when winter ends, so that you would winterize it properly before the grass growing season begins. For an average US lawn, blades typically need to be sharpened every four to six months if used regularly. For small-sized lawns, sharpening these blades only once per year should suffice. 

If you are regular with lawn care and grass mowing, then mower blade sharpening is something you will have to take care of. We suggest you always sharpen the blades at the start of spring and not before winterizing the lawn mower. The blades become dull even during storage because of fundamental factors, because if you skip doing so in the winter, it may become a little challenging, because you would start to mow and then face difficulties.

What Are Factors That Impact the Sharpness of The Mower Blades?

The factors that impact the sharpness of the mower blades are the frequency of mowing and the texture of the land; it also impacts the neatness and the size of the lawn. In addition to the height of the deck, and the quality of the blade that you have placed.

How sharp the blades of mowers stay throughout the year depends on several factors. Naturally, the blades lose their sharpness with use.

Sharpness of the Mower Blades

However, certain factors accelerate this dulling process faster than others. 

– Frequency of Mowing

Frequently cut grass type determines how quickly the blades will lose their sharpness. Grass varieties that are thick and coarse-bladed will dull the cutting edges faster than softer grass types during lawn care.

For instance, if you take the examples of Kentucky bluegrass, St Augustine, and Bermuda, they are popular lawn grasses with coarse leaf blades, and the more you mow them, the more you should check the sharpness of the edges of the mower.

– The Texture of the Land

The terrain on which your lawn exists plays a significant role in maintaining the sharpness of the cutting edges. People with flat lawns with little to no debris will not have to sharpen their blades as much.

Unfortunately, the blades will dull more frequently when the lawns are built on rocky and uneven terrain filled with pebbles, roots, and weeds because they would be hit by a bumpy road that it is getting run on.

– The Neatness and Size of the Lawn

Not cleaning the lawn well before grass mowing will not only dull the blades but might also damage them. The blade might incur damage if it comes in contact with a hard object like a rock forcefully.

Neatness and Size of the Lawn

In addition to this, you should also consider the size of the lawn matters a lot in determining the sharpness of the blades. Owners of small-sized lawns will not have to sharpen their blades as much as those with larger lawns, because the chore done would make the machine work much more than a small one would.

– Height of the Deck

When the height of the mower deck is kept low, there are more chances of pebbles and stones hitting the rotating blades and causing damage.

If you habitually keep the deck height low, you will have to sharpen the blades more often, because it is more functional when it is low, and the grass cutting is happening at a shorter size.

– Quality of the Blade

Investing in a good-quality blade made of durable metal will go a long way during lawn care. Blades of thicker and more durable metals will stay sharp for much longer and resist breaking and developing cracks. 

Why Are Sharp Blades Important?

Sharp blades are important because they would protect the quality of the grass, and now the grass would be less likely to catch any infestation of pests or diseases, and lastly, it would keep the lawn more manicured and healthy looking. 

The correct sharpness of lawn mower blades is of utmost importance in lawn care for several reasons. We know that sharp blades help cut grass quickly, more efficiently, and easily, but did you know that a dull blade can damage grass?

– Protecting the Quality of the Grass

Dull or improperly sharpened mower blades end up tearing and ripping the grass blades instead of slicing through them. If looked closely at, these blades look shredded with frayed ends, which means that when you invest in sharp ones, they will do the opposite of it, and keep the quality well protected. The result will be rich growth and grass growth will be healthy because all of its energies are directed toward growing and thriving.

Protecting the Quality of the Grass

Although, you will often see that there are some people who go years without sharpening their blades. The result is that these blades lift whole tufts of grass from the ground instead of ripping or shredding it, and this would mean that doing so, would give them a weak quality of grass.

– Less Likely To Catch Infestation

Grass mowed with sharp blades would not become wounded and at a decreased risk of catching infections. But a dull cut would take longer to heal than neatly cut grass with well-sharpened blades.

The result of a dull cut would be quite later, but if it doesn’t recover you will that the grass will turn yellow in yellow patches due to bacterial or fungal infections. 

– Keeps it Manicured and Healthy

A sharp blade makes fine cuts through the grass, enabling it to heal faster and preventing loss of moisture. This helps maintain a lush, well-hydrated lawn that looks fresh after each mowing session. If you have ever tried mowing with a dull blade, you will know how dehydrated and terrible the lawn looks afterward. 

The ability of a properly sharpened blade to cut grass easily is also beneficial for the lawn mower. A dull blade requires much more engine power to cut grass and messes up the mower’s inner working parts over time. 

Do it By Yourself?

To sharpen the mower blades by yourself, you should prepare the necessary tools, and then tilt the mower to the side and make sure you would adjust the stability. Afterward, you should remove the blades and sharpen them, and to test the edges you have to stroke them.

We advocate that you sharpen your lawn mower blades by yourself at home. With the right tools and guidance, this is a fairly straightforward process and will go a long way in maintaining your mower in top-notch shape. 

– Prepare the Necessary Tools

Take the mower out and place it on a solid, even, well-balanced surface. Essential protective wear you need to don includes thick rubber gloves, a pair of goggles, and full-sleeved clothing because you should be very protective not to hurt yourself in any way.

What you must do is to make sure that the mower has been turned off, and then disengage its spark plug to prevent it from starting accidentally. This plug is usually located on the side of most mowers behind the air filter, again, this is for protection.

– Tilt to the Side and Adjust the Stability

Next, tilt the mower on its side so that the blades and the deck can be accessed easily. When tilting the mower, see that the side with the engine and the fuel tank is facing upwards, but if it is a four-stroke mower, the air filter should be facing up.

Adjust the Stability of Mower

Then, you should put something behind the mower as a form of support to keep it from falling on you as you work, and to adjust the stability.

– Remove The Blades and Sharpen Them

Although you can sharpen the blades without removing them, it is best if you can remove them. All it takes is you unscrew the screws holding the blade and then place it in a vise.

You can sharpen lawnmower blades using several tools, namely a bench grinder, an angle grinder, or a simple file. What you should do is press the instrument firmly against the blade at the angle of the cutting edge. Sharpen the blade with firm, repeated strokes in one direction only, so that they would have a good edge.

– Stroke the Blades

Keep on checking the sharpness of your fingers after a set of about ten strokes. Only the lower side of the blade is to be sharpened. Never sharpen a blade using a back-and-forth motion. 

You do not want to over-sharpen the blade, either. Once it starts feeling as sharp as a butter knife without cutting the skin, it is sharp enough. Clean it thoroughly and then reinstall it back on the mower deck. Also, you should remember that the angled side of the blade always needs to be facing toward the deck so that it would adjust and fit properly.


This article discussed the ideal sharpness and how to sharpen these blades as a DIY project without professional help.

Here is what we covered:

  • Curious about how to tell if the mower blade is sharp? Just run a finger along its cutting edge. The ideal sharpness is when the blade is butter knife sharp and does not cut the skin.
  • Keeping this sharpness in mind, a blade with an average amount of use will have to be sharpened only about once per year.
  • Factors that dull mower cutting blades are lawn size, type of terrain, type of grass, and the type of metal that the blade is made of.
  • Sharp blades are important because they help cut grass better, faster, more efficiently, and with minimum damage.

After going through this guide, see if your blade is as sharp as it needs to be. You are also capable of sharpening a dull blade by yourself.

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