Taking the time to make an informed decision about the trimmer line you buy will save you a lot of frustration and some money in the long run. The diameter and shape of a trimmer line can have a significant impact on its efficiency and durability in your model of line trimmer.
Here are some considerations when choosing a trimmer line that is suitable for your machine and the job you are doing:
Check the manual for manufacturers’ recommendations
If you are unsure about the trimmer line to use with your line trimmer, the first place to check is the user manual that came with your machine. If you do not have a hard copy, it is usually pretty easy to find a copy online.
Line trimmers can only handle a specific range of line sizes (diameter) and it is important to get the right one for your machine. The wrong size of line will invariably slow you down. If you go too thick (i.e. heavy) it will not auto-feed in a bump head and it could cause damage to the machine in extreme cases. If you go too thin (i.e. light) you will end up with more frequent line breakages. In the longer run, this may cause a lot of wasted time and line and it can be hugely frustrating.
Be aware though that the manual recommendation is likely to be a diameter range only with no recommendations about shape. The assumption is that a round line will be used as it is a good all-rounder option.
Determine the optimal diameter for your line trimmer
Once you have established the appropriate range of line diameter to use with your machine, it is time to get more specific and pick the optimal diameter based on the type of trimming job you are planning to do.
Generally, the thicker the grass or weeds, the thicker the line should be. A larger diameter means more cutting power and usually more durability when cutting thick or dense grass or weeds. Keep in mind though that a thicker line means more wind resistance, which reduces the speed at which the head rotates. This is particularly relevant if you are using a cordless battery-operated trimmer as it will have an effect on the power and run time of the machine.
Be warned that if your aim is to get it absolutely spot on, it can become quite complicated. Our tests have shown that the type of head on your trimmer also plays a significant part in finding that sweet spot. It is about the amount of line on the head versus the weight (determined by diameter and shape) of the line. The same length of a heavier line creates greater centrifugal force and friction than an equal length of a lighter line, considering the motor typically spins at 7,000 rpm (it can be as high as 15,000 rpm). The bottom line is that with a head that takes pre-cut lengths you can get away with a slightly heavier line than a head that requires the line to be spooled. A minor detail, but if detail is your thing, it is worth knowing.
Finding the optimal diameter for your machine and terrain may be a bit of trial and error, but the general recommendation is:
2.0mm – 2.4mm: best for residential lawns with common lawn weeds, manicured lawns like golf courses and areas with young, soft grass. Trimmer engine sizes up to 25cc.
2.4mm – 2.7mm: large lawns and areas with mature weeds with heavy stems, light commercial. Trimmer engine sizes of 25cc plus.
2.7mm – 3.0mm: large sections, ideal for professional landscapers and contract mowers as it can handle thick grass, heavy weeds, small woody shrubs, dense underbrush. Trimmer engine sizes of 25cc plus.
3.3mm+ : suited to very heavy-duty work like lifestyle blocks, parks, reserves and areas with lots of obstacles like cemeteries. Brush cutters and other grunty engines.
Pick the appropriate shape for the job
The appropriate shape for the job is often as much a matter of preference as an informed decision. The combination of shape and diameter can determine how efficiently and fast you get the job done, so it is worth experimenting to find the best combination.
We have four shapes of trimmer line in the EVERCUT range – round, square, hexagon and twisted. For a detailed explanation, please refer to our blog: