Knowing how to properly measure a lawn mower blade will make it much easier to find the proper replacement. There are three major measurements to consider: length, width, and center hole. Other important measurements to note are thickness and distance between outer holes. Also take note of the center hole type and measurement.

LENGTH: Length is measured diagonally from one tip of the blade to the opposite tip of the blade. It is important to measure the length correctly. Measuring from end to end will result in the wrong blade length. All length measurements must be made diagonally. 

WIDTH: The width of the blade should be measured at the widest and flattest part of the blade – typically near the center of the blade. The width can be measured normally from edge to edge. 

CENTER HOLE: The center hole measurement will depend on the type of hole being

used. There are several different types of center holes: round, five-point star, six-point star, seven-point star, rounded rectangle, and H-pattern also known as bow tie. 

Round center holes should be measured for inner diameter. 5-point star, 6-point star, and 7-point star center holes will not have a measurement but will be denoted by name. H-pattern or bow tie center holes will also not have a measurement. H-pattern center holes will accommodate several different spindle types including 5-point star, 6-point star, or triangle spindles. 

Rounded rectangle center holes will typically have two measurements, inner length and inner height. Most lawn mower blades will have round center holes. 

Some blades will have an extra set of holes set to either side of the center hole. These outer holes are measured two different ways — individual diameter and the space between the holes. Measure the outer hole inner diameter the same way as a center hole. The correct way to measure the distance between outer holes is from the center of one hole to the center of the other hole. 

For more information about USA Mower Blades or for help measuring or determining replacement blades, please call customer service at 734-224-7758 or by e-mail here.