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Commercial Replacement Mower Blades

Commercial Replacement Mower Blades

How Often Should I Replace or Sharpen My Mower Blades?

As a general rule, lawn mower blades should be sharpened after about 25 hours of normal usage and will normally have to be replaced after 200 hours of usage. However, it all depends on the terrain being mowed. Terrain with rocks and heavy tree roots can easily damage the blades, and once damaged, mower blades need to be replaced. There are two things to look for to figure out whether you need to sharpen or change your blades.

  1. The appearance of Lawn. Dull and damaged blades won't cut the grass well. When the blades are dull, they tend to tear at the grass instead of cutting it cleanly. The ragged tips of grass allow moisture to escape from it, and this will turn the tips of the grass brown. The lack of moisture might also let diseases into the grass and kill it. Getting an uneven cut is also a sign the blades have been damaged to the point where you need to replace them. One side of the cut will be higher than the other, and you'll often have to go over an area more than once to even it out.

  2. Blade Condition. A good way to tell how the blades are doing is by taking a close look at them. If they are dented or bent out of shape, they need to be replaced. If the edge of the blade is rounded, but there aren't any visible signs of physical damage, you can usually get away with just sharpening them for now. However, if the edge of the blades has been thinned out from too much sharpening, it's time to replace your mower blades.

How Do I Measure My Lawn Mower Blades?

To properly measure the blades, you need to do the following:

  • Measuring the Length. A blade is measured from the tip on one side of the blade to the tip on the other diagonal side. The measuring tape should cross the blade and not run along the side of it. If you measure the length just along one side, you will get a faulty measurement.

  • Width. The width should be measured across the middle of the blade where the center hole is located. This is also where the widest and flattest part of the blade is.

  • Center Hole. Only two types of center holes have to be measured: round and rounded rectangle. You'll need to measure the inner diameter of rounded holes and the inner length and height of rounded rectangle holes. Other types of center holes, such as 5, 6, and 7-point star holes and H-styled holes, don't need to be measured since they come in a standard design. Most mower blades have rounded center holes.

  • Multiple Holes. Some blades have two extra holes — one on each side of the center hole. The diameter of each hole and the space between them should be measured.

What Type of Lawn Mower Blades Do I Have?

You will have to do a visual inspection to learn what type you have. There are five different types of mower blades.


This is the most popular type of blade found on mowers. The cutting edge of the blade is flat, but there is a curve on the non-cutting side to help give it an aerodynamic design. The design creates suction to lift the blades of grass up to be cut and then to direct the cut grass to a side discharge point. These blades are good for cutting dry or wet thick grass in any kind of soil.


These blades are less curvy than standard ones and don't create the same amount of suction because they are designed to work in sandy soils. The lower amount of suction helps to keep the grass anchored in the sandy soil. It also helps stop dust and sand from filling the air as you mow. These blades are smaller, typically 3 to 4 inches long, and need less power while cutting. This can extend the life of a lawn mower.


These blades are made to create suction to lift the blades of grass straight so they can be cut. High-lift blades range in length from one to 21 inches. The high amount of suction helps to keep the discharge chute clean by preventing the grass from clogging it up. These blades should be used in thick soils since they can pull the grass out of sandy soils.


The curved surface on mulching blades serves a couple of purposes. The suction raises the grass up straight and then cuts it into pieces with its segmented and ragged cutting edge. These blades are good for mulching up the grass enough to make it suitable to use as a fertilizer to enrich the soil. These blades shouldn't be used to cut thick and long grass.


Gator blades look and act like mulching blades, except they create a higher amount of suction to raise the grass up so it can be sliced into pieces with the ragged edge of the blade. These blades can cut through tall grass and are good for mulching leaves.

What Are Self-Sharpening Blades?

Self-sharpening blades don't actually self-sharpen. Instead, extremely hard material is applied to the bottom of the blade's cutting edge. The material is harder than the metal used on a standard blade and wears at a much slower pace. As the edge of the blade wears down, the hardened material underneath is exposed, giving the blade a new sharp edge.

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