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The Lawn Review: Home » How to Sharpen Your Lawn Mower Blades: 2023

How to Sharpen Your Lawn Mower Blades: 2023

Sharpening your lawn mower blade is one of those underrated tasks that you do every few years to revive your yard. I noticed pretty recently that my lawn had some split ends. If you know what I’m talking about, then it makes a lot of sense. 

This is the ultimate “tinkering in the garage” activity. The kind of thing you do when there are no sports on TV and you’ve really got nothing better to do. But for those of us that are perfectionists with our lawns, sharpening your mower blades is a huge necessity.

Let’s get started!

Why we review lawn tools

The reason we started this website in the first place was because we had so much trouble trying to find reasonable, understandable, honest reviews for lawn equipment. And it’s not cheap! After hours and hours of research, trying products and returning them, and messing up our yards – we started this site. 

review lawn tools
How we spend our time now.

As people who had to learn the hard way, we want you to know exactly what you are signing up for before you purchase a piece of equipment. That’s why we are committed to providing honest, easy-to-understand reviews that mean something.

Why you should sharpen your mower blade

You start to see brown tips on your grass where the blade just doesn’t perform like it used to. After mowing you look through your yard and it doesn’t look crisp. You miss some spots. Mowing your lawn took longer than it used to.

grass getting brown tips
Lawn is looking like Guy Fieri with the frosted tips!

These are the signs of a dull blade.

A dull lawn mower blade gives your yard a ragged appearance. If you don’t sharpen your lawn mower blade, you’ll end up with shredded or clumpy grass that looks unkempt. 

Thankfully, sharpening a lawn mower blade only takes a few minutes and doesn’t require a professional. The best time to sharpen the blade is at the beginning of mowing season, around early March. This preps it for the new season without it sitting through the winter season and getting dull. However, you can also sharpen the blades throughout summer and spring if you notice them becoming dull and have the time.

How to sharpen your lawn mower blade

We actually made this blog post originally as a Youtube short – a less than one minute video that covers all the high points. Here is what we recommend:

Step 1: Prepare the materials

You’re going to need a few tools to get this done the right way. The most important tool in this is the angle grinder. We use (and recommend) the Ryobi angle grinder, which we grabbed off of Amazon for a great price. With the angle grinder, you will want to be sure to have eye protection – so grab some safety glasses and gloves as well. 

Next up you’ll want some way of holding the blade in place. We used a bench clamp to really tighten the  blade in place, but you can also keep it on the ground with weights if you’re really looking to MacGyver it. 

You may also need a socket wrench (we did) to remove the bolt that is holding the mower blade to the mower. 

Because stuff is going to be flying everywhere, make sure you have some rags handy for a clean up and quick blade polish. You may also want a face mask to keep out any fragments from getting in your mouth or lungs. 

sharpen mower blade use bench clamps
Bench clamps rock.

Step 2: Remove the mower blade

The next step in this process is to remove the blade(s) from the mower. If you have a gas-powered lawn mower, start by removing the spark plug. This is a safety measure to avoid  the blades somehow getting activated while you’re down there taking them off. I liken this safety measure to turning your car off when you get gas. (This is a Honda HRN mower).

Next, lay the mower on its side. 

mower laying on its side to remove blades
Lay it down gently.

Then use a socket wrench to remove the bolts holding the blades to the mower.

remove  lawn mower blade
Pop those bolts off to remove.

While you’re down there, give your decking a nice power wash to get off all the old grass and prevent rusting. 

Step 3: Use the angle grinder to sharpen the blade

Once you’ve removed the blades from the mower, it’s time to sharpen these puppies. First, make sure to really clamp the blades down so they don’t move during the angle grinding process. We used a bench clamp to keep it held in place. If you don’t have one, try to find some way to keep it extremely secured down during the grinding process.

Next up, grab your angle grinder. We used the Ryobi angle grinder mentioned earlier with a 60 grit sandpaper disk. 

angle grinder sharpen mower blades
Grab the angle grinder and get to work.

Once you’ve got the grinder set up, get it spinning and follow along the natural edge of the mower blade. You can move back and forth to get it completely polished and sharpened along the edge. There isn’t a super exact science to doing this other than closely following the edge, making sure to sharpen the entirety of the blade from the tip all the way to the center. 

Step 4: Balance and reattach the sharpened mower blade

One last step that is often overlooked is making sure the blades are balanced. It’s as easy as setting it on a hanging nail to make sure you don’t have a lopsided blade. Balanced blades are important for keeping an even cut. 

If they aren’t balanced, then you can likely shave down the side that’s heavier with the grinder until you find it becoming more even. If that doesn’t work – it may be time for a new blade.

balance sharpened mower blade
Perfectly balanced. As all things should be.

Overview of steps to sharpen mower blades

  1. Get your tools together:
    • Eye protection
    • A few rags
    • An angle grinder 
    • Safety gloves
    • Bench clamps
    • KN95 face masks to protect yourself from dust
  2. Lay your lawn mower on its side 
  3. Remove the spark plug and mower blades
  4. Use an angle grinder with a sandpaper wheel to sharpen the slanted side of the blade
    • Make sure to grind at a natural angle to avoid damaging the metal
  5. Balance the blades
  6. Put the blades back on the lawn mower the same way you took them off
reattach mower blades
Reattach that sucker.

Once you finish sharpening the blades, you’ll notice that your grass looks much cleaner after mowing. Nevertheless, one of the most important parts of sharpening a blade is the grinder you use (and how you use it). A subpar grinder can leave you with a lawn that looks even worse than before. Therefore, I recommend choosing a high-quality angle grinder to sharpen your lawn mower blades and achieve the best result. 

Frequently Asked Questions

Want to learn more about what it takes to sharpen lawn mower blades? Here are my answers to the most frequently asked questions. 

How often should you sharpen lawn mower blades?

As a general rule of thumb, you should sharpen a mower blade after 25 hours of use. If it takes an hour to mow your lawn and you mow it once per week, you need to sharpen the blades after 25 weeks.

How do I know when to replace my lawn mower blades?

Telltale signs that you need to replace your lawn mower blades include patchy spots in the grass or visible damage to the blade (dents, chips, etc.).

Can you sharpen lawn mower blades without removing them?

Yes, you can technically sharpen mower blades without removing them from the mower. However, keeping them on the mower while you sharpen them isn’t the best approach. Using an electric grinder, you could easily sharpen the blade at the wrong angle and ruin it OR the blades could start spinning and cut your hands off. However, using a tool to file the blades manually isn’t as risky.

How do you sharpen a lawn mower blade by hand?

You can sharpen a lawn mower blade by hand with a file. I personally like the Kapoua Needle File Set with six metal pieces. Alternatively, you could get an electric grinder and finish sharpening the blade in a fraction of the time. 

The Bottom Line: Sharpening mower blades

Sharpening lawn mower blades is fairly simple. To recap, you’ll want to remove the spark plug before getting to work. After removing the spark plug, put the lawn mower on its side and remove the blade (either one or two blades, depending on the mower). Place the blades on nails to keep them balanced and sharpen them using an angle grinder or file. Once you’re finished sharpening the blades, put them back on the lawn mower the same way you removed them.

You should sharpen the blades after 25 hours of use or when you notice patchy grass after mowing. 

nv-author-image

Alex is a lawn tool enthusiast who cut his teeth as a normal Joe lawn dad. After burning through expensive, fancy tools, Alex became dedicated to finding the best tools on the planet. He is now a leading expert on electric lawn tools, quoted in the Washington Post among other publications.