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Should I Sharpen Or Replace Lawn Mower Blades? Here's Our Advice..

Written by William
Last Updated on August 31, 2021

Sharpening Or Replacing Your Mowers Blades - Our Guide

When the time comes to inspect your lawnmower's blades, you might be wondering whether you need to replace them, or just give them another sharpen.

By rule, you should replace your blades at least once a year, but if they show signs of irreparable damage such as them being bent or cracked, then you might need to replace them sooner. If your blades are still new and the cutting edge just looks a little dull, then sharpening them is the better choice.

We have listed out some simple ways to determine if you just need to sharpen or replace your blades in a guide below, and how to do both methods if needed.

Should I Sharpen Or Get New Blades?

Before we get on to how to sharpen and replace the blades of your mower, it's a good idea to know when it's time to fully replace them or just give them a quick sharpen.

Signs that your blade needs just sharpening are -

  • Your grass is looking torn rather than cut and your blade is still new.
  • The cutting edge to your blade looks blunt.
  • It's cutting the grass unevenly.
  • They are still thick.

If the blade of your mower reaches these criteria above then you should be fine to just sharpen your blades rather than replace them.

Signs that your blade needs replacing are -

  • The blade is cracked, damaged or bent.
  • The blade is thin.
  • Two/three years of age.

When your mowers blades start to get brittle and thin or they are suffering visible damage with cracks, you need to replace them straight away, as just sharpening them could cause the blades to snap during use if they have reached the end of there life.

When Should I Replace Or Sharpen My Mowers Blades?

Figuring out when to replace or sharpen your mowers blades comes down to individual usage.

If you mow a large garden and want to keep your lawn looking professional, you should aim to sharpen your blades twice a season or for every 25 hours of use.

In terms of replacement, once a year should be fine, but you may have to replace the blades sooner if they get damaged or cracked.

Sharpening your mowers blades may have to be done more often if your garden has a lot of obstacles that are wearing down the blades cutting edges such as leaves and tree roots.

How To Sharpen Your Mowers Blades

If you have decided your blades need to be sharpened instead of replaced then we have put together a small step by step way to sharpen your mowers blades in the safest way possible below.

Tools Needed

  • Gloves.
  • Goggles.
  • A metal file.
  • Vice.


  • Step one - Tip your mower over with the air filter and carburettor facing up towards the air, remove the spark plug to avoid any accidental start-ups of the mower.
  • Step two - Use a flat metal file to sharpen your blade at a 45-degree angle.
  • Step three - If you find that your blade needs extra attention and is unbalanced then remove the blade completely by undoing the bolts with a wrench.
  • Step four - Secure the blade in a vice and disc grind the blade instead, try not to go overboard and grind until your blade is shiny again, check the balance after with a blade balancer before reattaching the blade.
  • Step five - Secure your blade back on, but not too tightly.

How To Replace Your Mowers Blades

If your mowers blades have irreparable damage, then you need to know how to replace them rather than sharpen them.

Tools Needed

  • New blades of the correct type and size.
  • A socket wrench.
  • Gloves or safety equipment.
  • An Allen key.


  • Step one - Start by disconnecting the spark plug from your mower and tipping it on its side as we did in the sharpening steps.
  • Step two - Use a wrench to take off the bolt which is securing the blade to your cutting deck on the mower.
  • Step three - Remove the old blade of your mower and put it somewhere safe, insert your new cutting blades in the right direction and ensure they are balanced.
  • Step four - Secure the new blades by tightening the bolts and make sure they still have movement when hit so as they can absorb impact rather than shatter.

What Type Of Blades Should I Choose For My Mower?

If your planning on replacing the blades of your mower or you want to get a spare set in case your old ones get damaged, you might be wondering what type of blades you should go for.

It can be useful to have different types of blades for your mower depending on how you want to cut your grass.

We have listed out the two main types of mower blades below -

  • Discharging - These types of blades are additionally known as lifting blades and are designed to produce airflow which pulls grass up for the cutting process. The blades have a curved edge and come in either low lift, medium-lift or high lift, with the highest lift being the most suitable for long and thick grass.
  • Mulching - Mulching blades allow your grass clippings to be grounded up, acting as a home-made fertiliser for your lawn. These blades are sometimes known as 3 in 1 blade and make your mower work a lot harder.

Frequently Asked Questions About Deciding When To Sharpen Or Replace Your Mowers Blades

Do I need to sharpen my mowers blades when they are new?

No, when your blades come straight from the manufacturer they do not need to be sharpened and can be put straight on to your mower.

What can make my blades wear out faster?

Using your mower on very overgrown grass or sticks and debris can cause the blades to wear out faster.

Are there universal mowing blades?

No, there is no such thing as universal blades, however, you can find blades that fit on multiple different manufacturer models as long as the blade matched the thickness, length, width and hole sizes of your mower.

Last Words

To conclude, figuring out when to sharpen or replace your mowers blades will be based on your individual use and inspection of your blades, you should always replace the blades of your mower straight away if they become damaged.

About the author
Written by William
I have always had a passion for gardening and that with a background in selling lawn mowers for the past 10 years, I have become very knowledgeable in all types of gardening tools. The site was created as a hub where I can review and write about all of the tips around gardening.
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