Identifying the right replacement for your lawn mower blade can be a challenge, especially if you don’t have the OEM part number or model information. This is why understanding the industry standard for measuring is important as it’s not always a straightforward process.

Drawing on our experience as a leading lawn mower blade manufacturer for various OEMs, we not only cater to our customers’ requirements but also consider the needs of their clients. In the following, we provide a clear guide on how to accurately measure a lawn mower blade every time.


Begin by measuring the length. Turn off the lawn mower and disconnect the spark plug to avoid unintentionally starting the mower.

Next, find the blades under the lawn mower deck. Lawn mower blades usually aren’t symmetrical, lengthwise. The standard, consistent method is to measure diagonally from the end of one cutting edge to another. In other words, measure from the sharpest corner of one end of the blade to the sharpest corner of the other end. These will be on opposite sides of the blade.

To simplify your search, record the measurement in both inches and millimeters. Note that the more a lawn mower blade is sharpened, the smaller it will become, meaning it will no longer have the exact dimensions as when it was new. If that’s the case, allot for a slightly longer length when comparing new lawn mower blades.

Curved or damaged blades require greater estimation. The most efficient method in this case is to measure several points along the cutting edge, and then calculate the average length.


The width of a lawn mower blade is easier to measure than its length. Again, keep the spark plug disconnected and ensure the lawn mower is completely off.

Make the blade accessible and simply measure the blade’s width at the widest part. This maximum width is typically at or near the center hole. Make sure to keep your measuring device straight, rather than curving it across the blade. Also, be sure you’re measuring exactly parallel to the blade’s width, and record both inches and millimeters.

Center Hole

Unlike measuring the width and length, measuring a lawn mower blade’s center hole requires removing the blade. Make sure you have the following items:

  • Thick safety gloves
  • A measuring device (calipers, if you have them)
  • A solid, flat, and stable surface

With the lawn mower off and the spark plug disconnected, remove the blade according to the manual or other manufacturer instructions. Removal usually only requires unscrewing a bolt or nut assembly running through the center hole, which will detach the blade from the mower deck.

Set the blade on a flat surface and measure the diameter of the center hole. Sometimes there are side holes on either side of the center hole, which you’ll also need to measure. If so, take two measurements of the side holes:

  1. The diameter
  2. Distance between side holes, from the center of each one

What about irregularly shaped holes? For star-shaped, H-pattern, or other unique holes, you only need the name of the hole.

As mentioned, taking all measurements in inches and millimeters ensures you will have the easiest time researching replacement lawn mower blades. Throughout the process, be extremely cautious of all sharp edges. Also, be certain the blade is perfectly secure before attempting to use the lawn mower again.

Lawn Mower Blades From Fisher Barton Group

Fisher Barton Group’s blade division applies extensive experience in metallurgy and blade design and manufacturing to numerous industries. We produce lawn mower blades for dozens of leading brands, positioning us as one of the most reliable upstream suppliers for numerous product lines sold throughout the world. Contact us to learn more about our custom blade engineering services, and tell our knowledgeable technicians about your company’s lawn mower blade design and manufacturing needs.

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