When it comes to keeping a lawn neat and tidy, the string trimmer shines as a multi-purpose workhorse. Depending on the application, one could use it to mow down hard-to-access areas, trim up grass and weeds that a mower can’t quite reach, clear out thicker brush, and edge out lines for a cleaner looking yard. But, with such a variety of possible applications, as well as possible attachments to meet those demands, it can be difficult to settle on one specific set-up. So, what size string trimmer line should I use? The easy answer is that it depends on how much variable functionality I need from my string trimmer.
How It Works
Generally speaking, a string trimmer uses a monofilament line to cut through grass, weeds, and small, woody plants. By spinning at a high speed, a cutting head generates enough centrifugal force to hold the line out at a stiff, horizontal angle, making cutting possible. The height and arc of the string trimmer are manually adjusted by the operator, making the trimmer quite useful for cutting around trees, walls, rock beds, etc. In addition, the trimmer can be turned vertically to edge out lines near sidewalks and driveways.
On many models, the cutting heads and lines can be switched out to accommodate a variety of line gauges. Of course, you should check to see what gauges your cutting head can handle, but, depending on the job ahead, you will have plenty of options available. Thinner spooled line, thicker pre-cut line, serrated and square lines, or even blades or chains could be used. Trimmer lines also come in a variety of shapes and thicknesses, as well made from a variety of material. So, which line works best for which application?
String Trimmer Line Thickness
This probably comes as no surprise to anyone, but the general rule with string trimmer line is that the tougher the application, the thicker the line needs to be. A larger diameter will increase the power and durability of the line, which leads to less breakage and wear-out.
String trimmer line comes in a range of thicknesses. For light work, such as trimming grass, 0.065″-0.085″ should be sufficient. For thicker grass and weeds, a line in the 0.085″-0.110″ range will get the job done, and for thicker underbrush, anything thicker than 0.110″ will work.
One note for the cordless string trimmer users: thicker strings will have an effect on your power and runtime. As the thickness of the line jumps up, more wind resistance affects the cutting head, slowing down the speed at which the engine can rotate the cutting head. Higher voltage and beefier cordless trimmers (see: the EGO Power Head String Trimmer ) will probably be able to manage thicker gauge line more efficiently, but lower voltage models might struggle with a thicker line. Generally, it’s best to refer to the manufacturer’s recommendation for string size.
String Trimmer Line Shaping
The shape of the line also affects the cutting efficiency. String trimmer line comes in a variety of shapes: round, twisted, square, star shaped, and serrated. Rounded line is the most common type available, but it because it lacks a cutting edge, it rips the grass rather than cutting it. Twisted line is a bit better, as the shape has a little more of a cutting edge to it.
Some line comes in a square or star shape. The edges of these string trimmer lines are sharper than rounded trimmer line, and cut through the grass rather than tear at it. Serrated line is also an option when it comes to sharper trimmer line. It has teeth, similar to a kitchen knife, and saws through heavier grass and weeds with relative ease.
String Trimmer Line Material
Nylon line is the most common line available, but it tends to wear out and break quickly on anything but lighter duty jobs. Manufacturers have come out with a variety of alternatives for heavier duty jobs, however. Some examples include reinforced composite nylon, internally reinforced nylon, and aluminum additives for added strength.
Although not line in the technical sense, some of the beefier string trimmers can work with nylon, or even metal, blades. All of these options improve the durability of the light gauge nylon string, but if the vast majority of your trimming work centers on light grass clipping, you can probably get by with cheap, simple nylon line.
So, what type of string trimmer line should I use? The easiest answer: probably the heaviest and sharpest gauge that my trimmer can effectively turn without losing power to wind resistance. Assuming your string trimmer has the power, which should be the case for the pro landscaper, you won’t lose cutting efficiency by using a heavier line on lighter duty jobs. And, if you need to jump over to heavier duty trimming work, you won’t have to mess around with switching over to a line that can handle it.
However, for most homeowners, round nylon line will probably tackle the vast majority of simple trimming needs. You might need something heavier for edging and clearing out underbrush, but for handling grass around the house and yard, light gauge round nylon works. Of course, this assumes normal wear and tear on the line won’t bother you too much. If you want to spend less time respooling your cutting head, switching to a more durable material is an option, although a pricier one.