How to Change Lawn Mower Blade

In Brief: How to Change Lawn Mower Blade

Disconnect the spark plug line and put plastic wrap under the fuel tank lid, or unplug the battery for electric mowers. Tip the mower onto its side, hold the blade in place, and unscrew the fastening bolt. Screw in the new blade, making sure it faces the right direction. Replace plugs and remove plastic wrap from the cap before use.

Both gas and electric lawn mowers need their blades sharpened annually. However, some blades are beyond sharpening and need to be replaced. If your mower blade isn’t cutting well anymore, even after being sharpened, it might be time to replace it with a new blade.

Replacement blades are widely available for most modern lawn mowers. It’s easy for anyone to learn how to change lawn mower blades and to do it at home. Use this guide to get started today.

How to Change Lawn Mower Blade: Detailed Answer

Replacing a lawn mower blade is a simple 3-step process. It should only take you a few minutes to remove the old blade and install a new one, as long as you have the parts and basic tools available. Here’s how to change a lawn mower blade in minutes:

  1. Step 1: Accessing the Blade

    Before you can work on your lawn mower’s blade, you need to tilt the lawn mower to reach it. Start by disconnecting the spark plug line on a gas mower, or unplugging the battery on an electric mower.

    For gas mowers, it’s also wise to put plastic wrap or aluminum foil under the gas cap to prevent spills. Secure the plastic or foil in place with the cap.

    Tilt the mower on its side, or lean it back on the handles and lay something heavy on top of the handles to hold it in place. For blade replacement, tilting the mower onto its side makes it easier to access the blade. You should be able to reach the blade and the bolt securing it in place.

  2. Step 2: Removing the Blade

    Find a wrench that’s appropriately size the remove the securing bolt. Most mowers have a single large bolt, but some models have two small bolts holding down the blade.

    Because the blade on a mower spins in circles, the blade must be held in place before you can undo the bolt. You can hold it in place with a gloved hand or towel, or you can wedge a piece of wood, metal, or another hard material between the mower deck and the blade.

    Once the blade is immobilized, unscrew the bolt(s) and remove them. The blade should come off easily at this point.
    Keep all bolts, washers, and other parts somewhere they will not be lost.

    While the blade is off, take the opportunity to scrape away grass, mud, and debris from the mower deck. It’s better to clean the mower before putting in a new blade to prevent immediate damage or stress.

    Tip: If the bolt is rusted in place or too tight to unscrew manually, use a bolt loosening spray. Always use the right size wrench to avoid stripping the bolt. Bolts that are already stripped or overly rusted may need to be replaced along with the blade.

  3. Step 3: Attaching a New Blade

    After the old blade has been removed, take your new blade and put the securing bolt throw the center holes. Make sure the blade is facing the correct direction. Most blade are marked to tell you which side is the top or bottom, but you can also refer to how your old blade sat.

    Screw the new blade into place. Fasten the bolt(s) tightly. To get the bolt screwed in completely, you will need to hold the blade in place as you did with the old one while removing it. Work carefully because the new blade is much sharper than the old blade.

    Now that the new blade is installed, set the mower back on its wheels. Reconnect the spark plug or battery, and remove the plastic or foil from underneath the gas cap. Your lawn mower is now ready for use.
    View this simple guide to changing your mower blade:


Should You Replace or Sharpen Your Blade?

Sharpening is a regular part of lawn mower maintenance. How do you know when to replace a lawn mower blade or simply sharpen it?

While sharpening helps to put a fine edge on the blade again, some blades won’t perform well even if they are sharpened. It’s likely time to replace your blade if any of the following conditions apply:

  • Visible damage in multiple places, even after sharpening
  • Blade is bent or disfigured
  • Cutting edge is too thin (check manufacturer recommendations for your mower)
  • Rust is covering a large portion of the blade, especially the cutting edge

Professional landscapers often replace their blades annually, but for the average homeowner this is probably not necessary. Pay attention to the condition of your mower blade as you sharpen it to see when it’s time to replace the blade.


It’s easy to learn how to change lawn mower blades! It’s as simple as securing the mower, removing the old blade, and putting a new blade in its place. Give it a try today and see the difference it makes for your lawn.

Have you every changed a mower blade before? If you have any questions, let us know in the comments!

About Sharon Martin

Sharon loves to work on power tools and provides handyman services. She is an expert with both wood and metalwork. When free, she loves to hear country music and spend time with her cats.

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