How to Measure Mower Blades

Are you in need of new mower blades for your lawn but need help knowing where to start when it comes to measuring them? Purchasing the wrong size can result in more work or, worse, possible damage. To help alleviate the stress of choosing the right size blade for your machine, we have broken down exactly how to measure your mower blades.

How to Measure Mower Blades

Mower blades come in different sizes and styles, so it is essential to find the exact match for your specific lawn mower. Following these steps will ensure a perfect fit for efficient cutting. Regularly replacing worn or damaged blades will help keep your lawn looking its best.

In this guide on how to measure mower blades we will provide simple instructions and tips that you can follow so that you get the correct-sized blade with minimal time and effort!

What Will You Need?

Before we get started, let’s make sure you have the tools needed to measure your mower blades. You will need the following:

  1. Measuring Tape
  2. Wrench or Socket Set
  3. Blade Balancer (optional)

Once you have these items on hand, let’s begin!

10 Easy Steps on How to Measure Mower Blades

Step 1: Check the Manual

The first step in measuring mower blades is to consult the owner’s manual for recommended blade size and type. This can usually be found in the maintenance section of the manual or online. If you need access to your manual, check with the manufacturer’s website for the information.

Step 2: Disconnect Spark Plug

For safety purposes, disconnect the spark plug wire from the engine before beginning maintenance work on your mower. This will prevent accidental start-ups. If you have an electric mower, unplug it from the power source.

Step 3: Remove Mower Blade

Next, you will need to remove the mower blade. Tilt the mower on its side, taking care not to spill any oil or fuel. Using the wrench or socket set, unscrew the bolt holding the blade in place. Be sure to hold the blade while removing the bolt to prevent it from falling. Once the bolt is loose, carefully remove the blade.

Step 4: Measure Blade Length

Now that you have the blade removed, it’s time to measure it. Place your measuring tape from one end of the blade to the other, following the curve of the blade as you do. This measurement is known as the ‘cutting length.’ Be sure to measure from the tips of the cutting edges, not the center hole. Note this measurement as it is crucial for purchasing the right-sized replacement blade.

Step 5: Measure Blade Width

With the length noted, the next step is to measure the blade’s width. Take your measuring tape and measure the blade at its widest point. This is usually towards the middle of the blade, between the two cutting tips. Write down this measurement, another critical factor to consider when purchasing a new mower blade.

Step 6: Measure the Center Hole Diameter

The center hole diameter is another critical specification for mower blades. This hole is used to mount the blade to the mower’s deck. To measure it, use your measuring tape to measure the diameter of the center hole. Make sure you measure it at the widest point. Record this measurement as well, as you will need it when selecting your replacement blade.

Step 7: Note Down Any Additional Holes

Some mower blades may have additional holes or slots used for mounting. If your blade has these, measure their diameter and the distance between the center hole and these other holes or slots. These measurements are essential in ensuring that your replacement blade will fit correctly onto the mower’s deck.

Step 8: Check For Any Unique Features

Look out for any unique features on your blade, such as a contoured shape, a unique cutting-edge design, or any other special characteristics. If your blade has these features, you must ensure that your replacement blade has the same attributes. Try to replicate these features as closely as possible.

Step 9: Purchase the Correct Blade

Now that you have all the measurements and noted any unique features, you’re ready to purchase your replacement blade. Use your recorded measurements to find a blade that matches exactly. Remember, using a blade that doesn’t fit correctly can damage your mower or result in an uneven cut.

Using a Blade

Step 10: Install Your New Blade

Once you have your new blade, it’s time to install it. Attach the blade to the mower deck using the bolt you removed earlier. Ensure the blade is mounted firmly before reconnecting the spark plug wire. Now, you’re ready to mow with a properly fitted new blade!

By following these steps on measuring mower blades, you can ensure a perfect fit and efficient performance from your lawnmower. Regular maintenance and replacing worn blades will help keep your lawn looking its best.

5 Additional Tips and Tricks

  1. Always Unplug First: For your safety, always ensure the mower is unplugged, or the spark plug is disconnected before you start measuring the blades.
  2. Use the Right Tools: A simple ruler or tape measure can do the job. For more accuracy, a caliper can be used.
  3. Measure Diagonally: To get the correct length of your mower blade, measure diagonally from one cutting tip to the opposite cutting tip.
  4. Check The Centre Hole: Besides the length, the diameter of the center hole and the distance between outer holes (if any) are essential when finding a replacement blade.
  5. Consider Blade Shape: Keep in mind the shape of the blade – straight, curved, or mulching, as it can impact the type of replacement blade you need.
Ensure the Mower is Unplugged

With these additional tips and tricks, you can confidently measure your mower blades and find the right replacements.

5 Things You Should Avoid

  1. Avoid Guesswork: Never guess the size of your mower blade. Incorrect measurements could lead to the purchase of incompatible replacements, resulting in poor performance or even damaging your mower.
  2. Don’t Overlook Wear and Tear: Do not measure a worn-out blade and assume that this is the correct size. Due to wear or damage, the blade might not be its original size.
  3. Avoid Using the Wrong Tools: While a ruler or yardstick could be used, they might need to provide precise measurements. Only use them if they’re your only option.
  4. Never Ignore the Centre Hole: Pay attention to the size and shape of the center hole when purchasing a replacement blade. Even if the length is correct, an incorrect center hole can make installation impossible.
  5. Avoid Incorrect Blade Orientation: Don’t forget to check which way the blade faces. Installing the blade upside down can cause damage to your mower or the blade itself.

By being aware of and avoiding these common pitfalls, you can ensure a more accurate and effective blade replacement process for your mower.

How Do You Check a Lawn Mower Blade?

To check your lawn mower blade, follow these steps:

  1. Remove the Blade: First, unplug the mower or disconnect the spark plug. Then, using a wrench, remove the bolts or nuts holding the blade in place. Carefully lift out the old blade and set it aside.
  2. Clean and Inspect: Clean any debris or grass clippings from the blade before measuring. Additionally, inspect it for any signs of wear or damage that may affect measurements.
  3. Measure: Using a ruler or tape measure, measure the length of the blade diagonally from one cutting tip to the opposite cutting tip. For more accuracy, a caliper can be used.
  4. Check Other Measurements: In addition to length, check the diameter of the center hole and the distance between outer holes (if any) to ensure compatibility with replacements.
  5. Install New Blade: After confirming the measurements, carefully install the new blade in the correct orientation. Use a torque wrench to tighten the bolts or nuts according to manufacturer specifications.
Using a Ruler

Following these steps, you can properly measure and replace your lawn mower blade, ensuring optimal performance and a well-maintained lawn. Remember always to prioritize safety and accuracy when working with lawn mower blades. 

What is the Proper Mower Blade Edge?

The proper mower blade edge refers to the angle or sharpness of the blade’s cutting edge. This is important to consider when choosing a replacement blade for your lawn mower.

Ideally, the blade edge should be at a 30-45-degree angle from the surface of the grass. This allows for effective and efficient cutting without causing too much damage to your lawn.

The too-steep angle can result in a rough cut and potentially damage your grass. On the other hand, if the angle is too shallow, the blade may not be able to cut through thick or tall grass effectively.

Regularly sharpen your mower blades to maintain the proper edge and ensure optimal performance.


After following the steps detailed in this post, you should now better understand how to measure mower blades like a professional. Don’t wait too long before re-sharpening them so as not to put unnecessary strain and wear on your lawnmower.

Not only will it make your job easier, but it’ll also ensure that you get a professional look, even cutting on every blade of grass. Caring for your yard could be one of the most rewarding activities for any homeowner; why not start by ensuring you have the right tools?

So go out there and ensure all your blades are in perfect condition, and keep enjoying those beautiful green grass all year round!

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Enrique Howard

Hi, I am Enrique. I started my professional life as a handyman and did a lot of external and internal repair of home and office with a little bit of electric and plumbing support. I have extensive experience in tools testing such as drilling, turning, milling, and non-conventional machining like EDM. So let me help you on your journey towards becoming an enlightened DIYer with amazing tools that you can use on your project.

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