How to sharpen a lawn mower blade

To achieve a perfect lawn you need a sharp blade - follow our step by step instructions below.

A STIHL RM 443 T petrol lawn mower in a garden with a house in the background

When to sharpen your mower blade

If you have a green garden to be proud of, it’s disappointing when you notice that your mowing is leaving behind uneven and ragged grass. This is easily avoided though, if you regularly and proactively sharpen the lawn mower blade.

Inspect the blade regularly

Don’t wait until mowing results deteriorate: check regularly to see if you need to sharpen or replace the blade.

Replace a damaged blade

If you find a crack in your lawn mower blade, don’t try to sharpen it. You need to replace the blade entirely.

How often to sharpen the blade

Even if your regular inspections don’t find any problem, you should sharpen your mower blade or take it to a dealer for sharpening after 20-25 hours of use.

A STIHL RMA 2 RV mulching mower on grass

Should I sharpen my own blade or take it to a professional?

Sharpening and balancing the blade correctly requires a lot of practice. STIHL recommends having the blade sharpened and balanced by a STIHL specialist dealer. 

Your STIHL dealer and other professionals have the right tools and expertise to sharpen your mower blade to a high standard, so this is the safest choice to ensure the job is done correctly. If you have the right tools to hand however, you can sharpen your own mower blade by following our instructions below. 

Sharpening the blade yourself

Every time you sharpen a mower blade it also needs to be balanced to prevent unwanted vibrations and damage to the motor during use. To do this you need a lawn mower blade balancer – a good eye won’t do the job. Damaged caused by an unbalanced blade will not be covered under the machine's warranty. 

Professional mower blade sharpening

If you prefer not to sharpen the blade yourself, your STIHL dealer will be happy to take care of it, and will usually sharpen the blade as part of a scheduled lawn mower service. Your dealer may also be happy for you to remove the blade from the mower yourself, and take it in for sharpening. 

STIHL professional tip: Have your mower blade sharpened by a professional who has all the necessary tools. This task can be done by a STIHL dealer.

A person wearing gloves removing the lawn mower blade from a tipped-up STIHL RM lawn mower

How to sharpen a lawn mower blade: step-by-step instructions


  • Vice
  • Work gloves
  • Spanner
  • Monkey wrench/pipe wrench
  • Workshop files
  • Grinding stone or whetstone
  • Balancer
Close-up of someone putting on STIHL work gloves

Always remember: safety first

Before you look at the blade, make sure that your lawn mower is definitely switched off and cannot accidentally restart: remove the battery from a cordless lawn mower; pull out the spark plug connector on a petrol mower; or unplug the cable to an electric lawn mower. You should always wear gloves and safety glasses to sharpen lawn mower blades, as well as when removing and refitting the blade. Of course, the safest choice is to have the lawn mower blade professionally sharpened.

Summary: how to sharpen a lawn mower blade

  • Keeping your lawn mower blade sharp is the key to a well-tended lawn.
  • You can either sharpen your own lawn mower blade or have it professionally sharpened.
  • Always ensure the lawn mower cannot start before sharpening.
  • Always wear gloves and safety glasses to remove and fit the blade, and to sharpen it.
  • The safest way to sharpen a lawn mower blade is to take it to a professional.