Picture of How To Replace a Lawn Mower Blade
Lawn mower blades must be replaced after so many hours of cutting, and the steps in this instructable explain how to perform this simple parts replacement.

Broken, dull, damaged, and mismatched mower blades can cause a number of easily-noticed symptoms.

Damaged mower blades can cause excessive vibration in the mower, while dull mower blades usually get noticed by the ugly, irregular patterns they make in the lawn.

Mower blades can be sharpened several times to extend their life and ensure that your grass gets a healthy cut, but they can only be filed so many times before a blade replacement is necessary.

If you need to replace a lawn mower blade, you can do so at eReplacementParts.com

Homeowners can save themselves quite a bit of money performing simple repairs like this one. New mower blades tend to be reasonably priced, and mower blade replacements usually only require the use of a wrench.

For information about matching a replacement mower blade to your mower, please read the article, Lawn Mower Blade Measurements and Types.

Steps to Replace a Lawn Mower Blade

Mower blade mounting designs vary, but the basic steps are usually the same. Most mowers have use a very simple blade mounting design like the mower we use below as an example .

Step 1: Set the Mower on its side

Picture of Set the Mower on its side
Always set the mower on the side that does not have a carburetor so that the mower's fuel does not leak out.

Make sure the gas and oil caps are screwed on tightly before tipping the mower.

Step 1 should read: Remove plug wire from plug. The last thing anyone wants to see is a lost finger because you accidentaly started your mower.

THANK YOU! Thank you for easy to understand instructions plus pictures. My boyfriend AND my adult son BOTH told me that I COULD/SHOULD NEVER set my lawn mower on it's side - EVER. I told them it was safe if I put it on the proper side - but they said there was NO "proper" side.
They agreed to settle on whatever YOU said, therefore I WON and was able to change my blade without any more interruption!
Thank You Again!
georion3 years ago
Small world !!!! i just ordered some parts for a mower from you guys !!!!!!!!!!!!!!!!!!
pfred23 years ago
I use a pneumatic impact gun to remove mower blades. Bang and it is done. If I had to do it with hand tools the last tool I'd pick would be a ratchet. I'd use either a breaker bar or the combination wrench like what you're putting the blade back on with. A few taps with a mallet or scrap of wood on the end of the tool in the direction you want to spin would loosen the nut fast.

I get dozens of sharpenings out of a blade too not just a few like you said. I sharpen my tractor blades every other cut and only replace them every other year.
rimar20004 years ago
I sharp it with the hand grinder. It functions!
Me too!
toolrepair (author) 4 years ago
Make sure to hang on to any mower pieces that help mount the blade, like the retaining plate pictured in Step 3.
That mower blade and nut look really clean compared to mine. How do you get the nut off when everything is covered with the green-black crud that won't come off?
I agree with rimar2000, all you need to do is sharpen the blade on a grinder.

Shouldn't you disconnect the spark plug in order to make sure the mover won't start if you rotate the blade?