How to sharpen lawn mower blades: a few steps to a clean cut

Overview: how to sharpen a lawn mower blade

• A sharp lawn mower blade helps achieve a clean, even cut.

• Check your mower blade regularly for signs of wear, damage or dullness.

• A damaged or cracked blade should be replaced rather than sharpened.

• For the safest result, have your mower blade professionally sharpened and balanced by a STIHL Approved Dealer.

• Before inspecting, removing or working on the blade, always make sure the mower is switched off and cannot start accidentally.

• For a battery lawn mower, remove the battery before carrying out any work.

• If you own a petrol lawn mower, disconnect the spark plug connector before inspecting or removing the blade.

• Always wear suitable work gloves when handling a mower blade and safety glasses when sharpening.

How do I know when to sharpen my mower blade?

If your lawn mower starts leaving behind uneven, torn or ragged grass, the blade may have become blunt. A sharp blade cuts grass cleanly, while a dull blade can tear the grass rather than cutting it. Regularly checking the condition of your mower blade can help maintain good cutting performance.

Inspect the blade regularly

Don’t wait until the mowing result noticeably deteriorates. Check the blade regularly for signs of dullness, excessive wear or damage. Always switch the mower off and make sure it cannot start accidentally before inspecting the blade.

For STIHL battery lawn mowers, remove the battery before carrying out any inspection or maintenance.

Replace a damaged blade

If the mower blade is cracked, badly notched, bent or otherwise damaged, do not attempt to sharpen it. The blade should be replaced. 

If you are unsure whether a blade can be safely sharpened or needs replacing, contact your local STIHL Approved Dealer.

How often should a mower blade be sharpened?

The amount of wear on a mower blade depends on how often you mow and the conditions you are mowing in.

As a general guide, inspect the blade regularly and consider having it sharpened after approximately 20 to 25 hours of mowing if required.

Mowing over sticks, stones or other hard objects can damage or dull the blade more quickly, so inspect the blade if the mower strikes an object or if you notice a sudden change in cutting performance.

Sharpening the lawn mower blade yourself

If you have the appropriate tools, experience and knowledge, a mower blade can be sharpened by hand. The blade does not need to be razor-sharp. The aim is to restore the cutting edge while maintaining the correct blade profile and sharpening angle. The blade must also remain correctly balanced after sharpening. A mower blade balancer should be used to check this before the blade is refitted. Before carrying out maintenance yourself, refer to the operating instructions for your specific lawn mower. If you are unsure, have the work completed by a STIHL Approved Dealer.

Professional mower blade sharpening

Your local STIHL Approved Dealer can inspect the condition of your mower blade and advise whether it should be sharpened or replaced. Blade inspection and maintenance can also be carried out as part of regular lawn mower servicing.

STIHL professional tip: If you are unsure about removing, sharpening, balancing or refitting a mower blade, take your mower to a STIHL Approved Dealer.