How to Remove & Replace Mower Blades: Easy Steps

PDF download Download Article
Swap out dull blades on any mower with our simple guide
PDF download Download Article

If your lawn is looking more ragged than usual after mowing it, the blade on your lawn mower might be dull. A dull blade can damage the grass, so changing the mower blade regularly can save the look of your lawn. Keep reading, and we’ll walk you through how to remove and replace a blade on a push mower and riding mower, plus how often you should change it.

Easiest Way to Change Mower Blades

Unplug the spark plug on your mower and tilt it back to expose the blades underneath. Wedge a piece of wood between the blade and deck, and use a socket wrench to remove the mounting bolt and blade. Place the new blade on your mower and retighten the bolt so it’s secure.

Section 1 of 3:

How to Replace a Push Lawn Mower Blade

PDF download Download Article
  1. Look near the front of the lawn mower’s engine for a thick black cord housing the spark plug. Disconnect the plug to prevent your mower from accidentally starting while you’re working. [1]
    • If you have an electric lawn mower, open the main compartment by the engine and pull out the battery.
    • For an added layer of security, cover the end of the spark plug with a small plastic bag. This prevents the contacts from accidentally touching while you’re replacing the blade.
  2. Tilt the mower back toward the handle and weigh it down so it doesn’t fall. It the mower doesn’t stay put, then try tilting it on its side instead so the blade is face-up and exposed. [2]
    • If you tilt the mower on its side, make sure the air filter on the side of the engine faces up. This prevents oil from leaking onto the filter and ruining it.
    • It’s usually best to replace a mower blade when the gas tank is empty so it doesn’t spill out when you tip it over. Either run your lawn mower until it runs out or siphon the gas out of the tank.
      • Alternatively, unscrew the gas cap, cover the opening with a plastic sandwich bag, and screw the gap back on to seal the tank.
    Advertisement
  3. Put on thick work gloves to protect your hands. Your lawn mower blade is usually connected with a single mounting bolt, but there may be more depending on your lawn mower. Wedge a wood block between the blade and the deck to prevent it from spinning. Then, use a socket wrench and turn it counter-clockwise to loosen the bolt enough so the blade pulls straight off. [3]
    • If the mounting bolt is stuck, lightly tap the handle of your wrench with a hammer to loosen it.
    • Save the mounting bolt and any washers that were with it because you can reuse them with the new blade.
    • Take a picture of the blade’s orientation before you remove it so you can install the new one the same way. Usually the sharp edge of the blade moves counter-clockwise, but double-check your mower’s manual to find the proper orientation for your model.
    • If the underside of your mower looks caked in dead grass or debris, then use a plastic scraper to clean it off so the new blade can spin properly.
  4. Get a replacement blade that’s the same size as the old one. Measure the old blade or take it with you to the store to compare sizes. Make sure to use a blade that has the same mounting holes and length to ensure that it fits onto your mower.
  5. Place the new blade onto the mounting bolt so the raised wings at the end are pointing toward the mower deck. Secure the mounting bolt by turning it clockwise by hand until it’s tight. Then, use a torque wrench to tighten the bolt until it’s snug. [4]
    • Be careful not to under-tighten or over-tighten the mounting bolt. Under-tightening can make the blade come loose while using your mower, and over-tightening can damage the bolt or blade.
  6. Tilt your lawn mower back to its upright position. Plug the spark plug back into the port at the front of the engine, or reinstall the battery if you have an electric mower. [5]
    • If you emptied the gas tank, refill your mower with fresh gasoline. Otherwise, remove the plastic bag under the cap before running your mower.
    • Wait about 30 minutes before using your mower after replacing the blade so the oil inside can return back to the motor.
    7. Advertisement
Section 2 of 3:

How to Change a Riding Lawn Mower Blade

PDF download Download Article
  1. Position your mower in an open space where you have room to work and set the parking brake. Shut your mower off completely and take the key out of the ignition so you don’t risk the mower starting while you’re trying to remove or replace the blade. [6]
    • If you recently used your mower, give it about 5-10 minutes for the engine to cool down before you start working.
  2. Look for the deck lever next to the mower’s seat. Shift the lever to the lowest number and height setting so the deck is against the ground. [7]
    • This prevents the mower deck from quickly dropping to the ground when you disconnect it.
  3. There are usually a handful of small metal clips on the front and sides of the blade deck securing it to the body of your lawn mower. Pull the retaining clips out by hand and set them aside somewhere you won’t lose them. Then, look for a U-shaped metal guard around the rubber belt on top of the deck and unscrew it from the machine. [8]
    • After that, the belt will easily slip off and the deck will slide out from the side of your mower.
    • The clip locations and parts you need to disconnect may vary between models of riding mowers, so check the user manual for your specific mower.
  4. Flip the deck over to expose the blades on the bottom. Wedge a piece of wood between the blades and the side of the deck to block the blades from spinning. Fit a socket wrench over the mounting bolt, and turn it counter-clockwise to loosen the blade. [9]
    • Repeat the process for each blade on the bottom of the mower deck. The mower blades wear out around the same time, so it’s best to change them both at the same time.
    • Wear thick work gloves when you’re removing and installing mower blades so you don’t cut yourself on the sharp edges.
    • Take pictures of the blades before removing them from your mower so you can remember how to install the new ones.
  5. Install and secure new blades to the mower deck. Get blades that are the same size and have the same mounting holes as the old ones. Fit the blades on the mounting holes so the raised wings are pointing toward the deck. Screw the bolts clockwise back onto the blades until they’re hand-tight. Then, use a torque wrench to finish tightening the bolts until they’re snug. [10]
    • Try to wiggle the blade to make sure it doesn’t move up or down. If you notice it moving, then tighten the blade more.
    • Avoid over-tightening the blades because they could warp or damage your mower. The bolts will also tighten more when you run your mower.
  6. Slide the deck back underneath your mower and fit the belt back around the pulley near the front of the machine. Reinstall the belt guard and place the metal locking clips back into position so the deck is secure. Then, you can use your mower immediately when you’re finished. [11]
    7. Advertisement
Section 3 of 3:

How Often to Replace Lawn Mower Blades

PDF download Download Article
  1. Replace the blade at the start of the season so it’s sharp throughout the summer and fall when you’re mowing the most. Because the blade dulls a little bit every time you mow, it’s best to use a fresh sharp blade so your lawn stays healthy. [12]
    • Some signs that your lawn mower blade needs to be replaced include:
      • Split or torn grass instead of clean cuts
      • Brown ends on your grass
      • Uneven lawn heights
      • Slower run speeds or difficulty pushing the mower
      • Dents or damage on the blade
  2. Professional landscaper Grant Wallace recommends residential homeowners who mow a couple times a month can sharpen their blade to revive it. You can try sharpening the blade yourself with a file or grinder, thought it’s often easier to have it professionally sharpened at a repair shop.
    • While sharpening helps a blade last longer, it also removes some of the metal and makes the blade thinner. If the blade is less than 1 ⁄ 2  in (1.3 cm) thick, then replace the blade instead.
    3. Advertisement

Expert Q&A

Search
Add New Question
  • Question
    How often do mower blades need to be sharpened?
    Grant Wallace
    Landscaper
    Grant Wallace is a Landscaper and Owner of Grantlanta Lawn in Atlanta, Georgia. With over seven years of experience, he specializes in lawn maintenance and landscape installation. In 2012, he earned his BA from the University of West Georgia. Grant has been profiled in Shoutout Atlanta, Canvas Rebel, and Voyage ATL.
    Grant Wallace
    Landscaper
    Expert Answer
    Residential homeowners who only mow their grass a couple of times a month only need to sharpen their mower blades about once or twice a year. To check your blades manually, remove the spark plug from the mower and run your finger along the blade. If it feels dull or round, it likely needs to be sharpened.
    Thanks! We're glad this was helpful.
    Thank you for your feedback.
    If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
    Yes No
    Not Helpful 3 Helpful 6
  • Question
    What do I do for a stripped bolt?
    Community Answer
    It depends on the definition of stripped. Is it the head of the bolt or the threads? If it's the head of the bolt it may be tricky, but an EZ out and a drill tap would get the job done, or a good pair of strong vice grips and a little heat from a propane torch should also assist with removing the bolt. If it's stripped threads on the bolt then probably take the bolt to your local hardware store and get an exact copy of the bolt depending on the threads (if it's coarse, fine or whatever). I am fairly certain it's a 3/8 fine thread on lawnmower blades, though.
    Thanks! We're glad this was helpful.
    Thank you for your feedback.
    If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
    Yes No
    Not Helpful 5 Helpful 7
  • Question
    Which way should the blade be installed?
    Community Answer
    The sharp edge of the blade should be installed facing the grass. If the blades have tabs to fit into the housing, then go ahead and fit the tabs into the housing around the shaft. Always wear gloves though (preferably leather).
    Thanks! We're glad this was helpful.
    Thank you for your feedback.
    If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
    Yes No
    Not Helpful 12 Helpful 8
See more answers
Ask a Question
200 characters left
Include your email address to get a message when this question is answered.
Submit
      Advertisement

      Video

      Tips

      • Lawn mowers vary in styles and each one may have slightly different blade removal and installation instructions. When in doubt, check the user manual for your specific model for complete instructions.
        Thanks
        Helpful 0 Not Helpful 0
      Submit a Tip
      All tip submissions are carefully reviewed before being published
      Name
      Please provide your name and last initial
      Submit
      Thanks for submitting a tip for review!
      Advertisement

      Warnings

      • Always disconnect power before removing or installing your lawn mower blade so you’re less likely to get injured.
        Thanks
        Helpful 0 Not Helpful 0
      Advertisement

      You Might Also Like

      Sharpen Your Lawn Mower Blade for a Clean, Precise Cut
      How to
      Change the Blades on a Riding Lawn Mower
      Preventing & Cleaning Grass Buildup on a Mower Deck: Best Tips & Tricks
      How to
      Start a Push Lawn Mower
      How to
      Start a John Deere Riding Mower
      How to
      Start a Riding Lawn Mower
      How to
      Clean a Lawn Mower Carburetor
      How to
      Repair a Lawn Mower
      How to
      Use a Riding Lawn Mower
      How to
      Repair a Mower Deck Spindle
      How to
      Dispose of a Lawn Mower
      How to
      Remove a Lawn Mower Wheel
      Advertisement

      Expert Interview

      Thanks for reading our article! If you'd like to learn more about changing lawn mower blades, check out our in-depth interview with Grant Wallace .

      References

      1. ↑ https://youtu.be/qFusHPPmOFo?t=63
      2. ↑ https://youtu.be/QuIGPMbedHw?t=23
      3. ↑ https://youtu.be/BX08cFe-Z1E?t=47
      4. ↑ https://www.consumerreports.org/home-garden/lawn-mowers/how-to-remove-and-replace-a-lawn-mower-blade-a1128582899/
      5. ↑ https://www.thisoldhouse.com/lawns/21016918/how-to-sharpen-a-lawn-mower-blade
      6. ↑ https://youtu.be/2n8Lpuygb48?t=24
      7. ↑ https://youtu.be/0AZ1DNaNcoQ?t=31
      8. ↑ https://youtu.be/bhRswHogqSQ?t=25
      9. ↑ https://youtu.be/0AZ1DNaNcoQ?t=103
      1. ↑ https://youtu.be/REhSK-SyBhE?t=30
      2. ↑ https://youtu.be/bhRswHogqSQ?t=159
      3. ↑ https://youtu.be/VRozHD9RAGQ?t=48

      About This Article

      Article Summary X

      Before you can change a lawn mower blade, make sure there's no gas in the mower and disconnect the spark plugs, then lift the deck of the mower to expose the blade. Next, use a wrench to loosen the mounting bolt holding the blade in place to remove it. If your old blades are chipped and worn out, replace them with a new set, then check they're in place correctly by making sure they don't wiggle up and down. Finally, refill the gas tank and reconnect your spark plugs to get mowing again. To learn how to sharpen your old blades, read on!

      Did this summary help you?
      In other languages
      Thanks to all authors for creating a page that has been read 453,497 times.

      Reader Success Stories

      • John Dawson

        May 23, 2017

        "Told me that the threads were normal, not reversed threaded. In other words, which way to unscrew the old blade. ..." more
        Rated this article:
      More reader stories Hide reader stories
      Share your story
      If you buy through links on our site, we may earn a commission .

      Did this article help you?

      Advertisement