How Sharp Should a Lawn Mower Blade Be?

Last Updated on May 9, 2024 by Sharaj

The lawnmower is a crucial garden tool. With the best one, you can guarantee a well-manicured lawn in the homestead.

The overgrown turf can be ugly and contains pests, so before you start mowing the lawn, ask yourself this question: What factors determine the best lawnmower’s ideal performance? The perfect performance depends on the efficiency of the mower.

This will article examine how sharp should lawn mower blades be.

Can Lawnmower Blades Be Too Sharp?

The blades need to be sharp, but they cannot be as sharp as the razor blade. When touching the edge, there is no need to cut your hand. This way, they will mow the grass gently and have clean but.

With the very sharp blades, they will get dull faster, and this will require sharpening much more frequently, which shortens their life.

How Sharp Should The Lawnmower Blades Be?

If the blades are very sharp, they will become blunt fast, although this may depend on the blade’s thickness. When you consider the blade’s sharpness, many questions arise like: how can they be? Typically, you need to ask the question of what if.

Nevertheless, if you plan to mow a yard with plenty of soft grass and weeds, it is best to sharpen the blades at a shallow angle. When working on wooded or uneven lawns, it is good to keep them a little blunter.

Most importantly, the sharpening angle at the blades’ edges needs to be always 40 degrees, but at least 30 degrees. Essentially, anything below this inclination is considered very sharp, making it more susceptible to pebbles, small stones, and dirt.

The lawnmower blade must depend on the terrain of the backyard and the nature of the grass. The simple rule of thumb is that the sharpness level (angling and edge beveling) must remain at the point for which you bought the lawnmower.

Do The Sharp Blades Of The Mower Make A Difference?

Do The Sharp Blades Of The Mower Make A Difference

Yes, the sharp blades make a big difference. During the spring season, when the grass is overgrowing and getting thicker, only the sharper blades cut well with the lawnmower using minimal effort. Also, you need to know the faster mowing with the sharp edges.

Therefore, we would say that the sharpness of the blades is essential with the lawnmower. For you to understand why sharp blades make a difference, you need to note the following:

  • Dull or nicked blades of the lawnmower will only crush grass to the cutting edges. This means that the lawn will end up in torn grass instead of straight and clean cuts. You do not want to have rugged and unsightly land, do you?
  • Grass that is torn means after some days mowing, your lawn will turn brown when the grass dries out at the torn edges.
  • However, torn, brown, and smashed grass is vulnerable to pest infestation and diseases, which will push the lawn’s maintenance slightly high. We bet you do not want to use that route at any cost for now.

How To Sharpen The Lawnmower Blades

Always check the sharpness of the blades. Although the blunt edges are easy to be detected by how they lawn the grass, experts recommend inspecting the blades’ sharpness when the spring starts (during the mowing season). Some of the blunt signs include nicks, bends, and dents. Those that divide the grass, leaving them brown and rugged after some days, are usually dull.

Also, remember that clearing the yard before mowing will make the blades to be sharp for a long time. Examine the yard and remove any debris, stick, stone, and rock that might cause them nick. Here are the steps for sharpening the lawnmower blades:

  • Wear protective gear when sharpening the blades. This includes safety gloves and glasses, which resist cuts.
  • Make sure you disconnect the spark plugs from the lawnmower. This is to protect the machine against any possibility of starting on its own.
  • You will need tools like rags, ratchet set or socket and vise for this job. Also, a sock of a spark plug becomes very crucial. You will need other items like lubricants, preferably WD-40 and gloves.
  • If the mower doesn’t have manual instruction that will give a step-by-step guide on how sharpening the blades is done, don’t worry. Our guide will help you with how to do it.
  • Hold a grinder when sharpening the blades, but with the nicks, the best-notch file needs to flatter them.
  • Secure the blade with the vise. Use a file, grinder, or other sharpeners to remove nicks or dents before sharpening it.
  • When sharpening the blades, balance them correctly. It is just like having sharp cutting edges.
  • Sharpen the mower blades in one direction with a bevel angle of 45 degrees. Nevertheless, you can proceed to about 30 degrees higher depending on the yard’s terrain. It is recommended to keep the edge of the blade sharp as with the scissors.

Important Information On Sharpening The Lawnmower Blades

  • You need to know that sharpening the lawnmower blades very often can mean replacing them after some months. However, from experience with the best mowers, a good one with well-tempered will last more than one year. According to this premise, the original one must mow for 1 to 3 years, even with numerous sharpening.
  • Keep the frequency of the sharpness to a minimum, for example, after the eighth mowing. Depending on the machine you’re using, blade tempering, and other factors, you need to flatten nicks frequently. More importantly, many experts recommend that homeowners sharpen their lawn mower blades at least two to four times annually. This will make them remain sharp for long.
  • If the mower blades are difficult to sharpen and level, contact the service provider for expert assistance. It should only cost a few dollars, typically less than $10, which depends on the blade’s condition.
  • Balance vibrations against guards so that the mowing engine and deck are not under stress. Do this before installing the blade again. A balancer tool is required to help you achieve even weight distribution on edge. Since you can get the best balance of around $5, you can choose from the competition as long as you get good value for the money you have.
  • You must be used to keeping the sharpness of the blade ideal. Therefore, always keep these tools in an area where you can get them when you need them.

Why Do The Mowing Blades Get Dull or Lose Sharpness?

You don’t want to wake up one day saying, “I am sharpening my mower blade.” Given that you are having a lawnmower that you ride or one you push, the crucial decisions, which improve the efficiency of your machines, shouldn’t be sudden. Factors that affect the dullness of the mower blades include:

Irregular and infrequent sharpening: Although the blades should always be sharp, this will result in the infrequent sharpening of the blades. It will be more difficult next time, maybe about six months, if you do not sharpen often. The irregular blade sharpening means uneven edge angling or beveling. Therefore, infrequent sharpening often causes blades to be dull faster than expected.

Thin blades versus thick blades: Thin blades are known for losing sharpness more quickly than thick blades, which need to be sharpened frequently.

Wear and tear: The lawnmower blades wear and tear out like all other parts of the mower. When they hit pebbles, stones, rocks, and sticks, the more they will be duller.

Mowing the grass closer to the ground: You will expect the lawnmower blades to get dull faster if you cut grass close to the ground. The problem is that if you want to make the grass shorter, the edge will be vulnerable to pebbles and stones, hence loosening the sharpness faster than when cutting higher grass.

When Should You Replace The Mower Blades?

Since it is paramount to keep the mower blades in perfect condition, there is a problem. Under what conditions should you change the blades? What factors are essential for such a decision? The reality is that these machines do tear and wear even with the best lawnmowers out there. After some years of use, worn parts must be replaced.

After replacing worn blades, you need to remember a few things. The first thing to do is use additional replacement blades, possibly from one manufacturer where you bought the new lawnmower brand. Old blades with a thin trailing edge require to be replaced.

Another factor which you need to put into consideration is a cutting edge. So, always ask a question: Can further sharpening cause the blade to be imbalanced? If that is the case, it’s time to buy a new one.


To conclude, you have learned that the lawnmower blades can be very sharp. Those which are very sharper become dull faster than very blunt ones.

Therefore, it is necessary to choose thicker blades rather than thinner ones to avoid regular sharpening. They need to be sharp enough to make it easy to mow and not very blunt to make freshly cut grass look ugly.

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