Choosing The Right Trimmer Head


With all of the replacement trimmer heads on the market today, finding the right one for your trimmer can be overwhelming.  But it doesn’t have to be.  This simple, 2-step guide will help you determine which trimmer head is right for your application.

Step 1)  Determine Compatibility

The most important step in choosing a replacement trimmer head is determining which one is compatible with your existing trimmer.  In order for a replacement trimmer head to fit properly, its center bolt (also known as the arbor bolt) must be compatible with the corresponding bolt on the trimmer.  Compatibility is determined by 3 different criteria:  bolt dimensions, rotation, and gender.

Dimensions:   The center bolt of the trimmer head should have the same diameter and thread count as the trimmer bolt. When using the metric system, the critical measurements are bolt diameter in millimeters and the thread width in millimeters (ex. 10mm x 1mm).  When using the U.S. standard system, the critical measurements are bolt diameter in inches and the number of threads per inch (ex. 5/16” x 24). 

Rotation:   The directional spin of the trimmer head should always be the same as that of the trimmer.   If the directional spin of the trimmer is to the left, the spin of the trimmer head should also be to the left.  If the directional spin of the trimmer is to the right, the spin of the trimmer head should also be to the right.  

Gender:  The gender of your trimmer head bolt should be opposite that of your trimmer.  So, if your trimmer’s bolt is female, be sure to choose a trimmer head with a male center bolt.  If your trimmer’s bolt is male, be sure to choose a trimmer head with a female center bolt. 

These three attributes will usually be clearly marked on the trimmer head packaging.  For example, 10mm x 1.25mm LHM indicates an arbor bolt with a 10mm diameter, 1.25mm thread width, Left Hand rotation, and Male gender. 

Today, many trimmer heads are universal, meaning they fit on most trimmer makes/models, either straight off the shelf or with the help of adapters.  Manufacturers of replacement trimmer heads may also place labels on packaging with cross references to original equipment parts, simplifying the process even more.


Step 2)  Choose Your Features

Trimmer head manufacturers offer a variety of ease-of-use features to appeal to consumers. These features usually pertain to how the trimmer line is installed and how the line is dispensed during operation.  A common frustration among users is manually replacing broken line caused by trimming alongside fences, concrete, rocks, and walls.  To remedy this, some trimmer heads feature a system designed to automatically feed new line after it breaks.  Other trimmer heads feed new line through a simple tap of the trimmer head on the ground (often called “bump feed” or “tap n’ go”).   Convenience factors such as these save time and help you get the job done quicker. 


If you’re on the market for a replacement trimmer head, AgristoreUSA carries both professional-grade and DIY-grade trimmer heads for nearly all makes and models.  Visit our web site and search the master chart, or call us at 317.329.5080 and allow our friendly sales team to assist you. 


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