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Weed Trimmer String Replacement Tutorial

Using a string trimmer effectively isn’t a difficult task but there are a ton of options available, and not just in manufacturer or overall style. One of the most important choices on your hedge & weed trimmer is what sort of line you use – Size, shape and thickness all play different and unique roles in helping you get the most out of your lawn care investment. We’re here to help break down the various types of string trimmer line, what they excel at, and how to know when to use them – Let’s get started.

What Makes One Weed Trimmer Line Different From Another

When it comes down to it there are usually only three major differences any one weed eater line can have from another: Thickness, material, and shape.


This one is easy: Most of your weed trimmer strings will be made of nylon. There are occasional special-interest products available that use other materials but the odds are if you need one of those? You already know about it. You’ll likely be sticking to nylon for all your weed whacking needs.


Thickness is another one that makes sense; the thicker the line the stronger the chopping power. But brute strength isn’t always the best solution, and putting the thickest line you can find on your string trimmer can just end up straining the engine and wasting fuel. Thicker line increases both resistance against the plants and in the air, making your trimmer work much harder than expected so stay in the manufacturer’s recommended range for best results.

Once you know what you can handle you can look into what the job requires. String for line-base trimmers usually come in one of three ranges:

* Light: .065-.080 inches in diameter. Best suited for light work such as grass or weeds that are easily broken/sliced down.

* Medium: .085-.105 inches in diameter. Good for when working in thicker, deeper grass or with weeds that, while not woody, still take a little force to knock down.

* Heavy: .110+ inches in diameter. For the jobs that require brute strength this is your line. This will start to cut through some woody weeds and can be used on very light hedge trimming work as well.

Again, thicker line can put more strain on your engine than needed and can cost extra fuel, even in trimmers that are rated for it, so make sure to pick the right thickness for the task at hand.


The final difference, shape, is where things start to get a lot more diverse. Different shapes of lines offer different benefits & cutting strengths, and knowing which is best suited for what work is important when choosing a new line. We’ll go over the major categories:

* Round Line: This is the most typical type of line found in consumer-grade devices & replacements. This line is cheap to manufacture & purchase, and is fairly hardy – The rounded shape means it holds together longer and is less likely to break. It does not offer the most precise cut, however; as there is no edge to the shape this line more “rips” grass and weeds rather than “cutting”. If you’re looking for the cleanest lines possible, consider a different style of line.

* Square Line: One of the more rugged shapes of string this type of line is often used for areas with dense, thick weeds that regular line would just break on. This shape is also fairly sturdy and good to use when working around areas with concrete or asphalt.

* Multi-Sided Line: These lines often have a pentagon shape to them and are heavily preferred by professionals. The multi-faceted shape gives this line a higher cutting power than round or square lines but is also more prone to breaking when striking a hard object.

* Twisted or X-Shaped Line: This type of line can be expensive but is often very strong, rarely breaking even when in use around rocks or concrete. Another solid choice for professional jobs or work in dense areas.

* Serrated Line: This line has a knife-like serrated edge and offers the absolute best cutting power of any type of line. However, due to its shape, this line is very fragile and will easily break if used in a rocky area. Also note: The cutting power of this line can make the weed trimmer feel as though it is being dragged “downward” in the direction of the grass/weeds being trimmed. This can be compensated for easily enough, but it is good to be aware of before beginning.

Outdated Model? Find the Best Battery Powered Weed Eaters Here:

If you’re looking for a little upgrade, check out our battery powered weed eater buyers guide for information on the latest and greatest. Just something to think about if you are looking for an upgrade.

We hope this guide has helped make a bit more sense out of the crowded world of weed trimmer string. In summary: Check your manufacturer’s guide or website to confirm what thickness of line it is rated for, try to use the appropriate thickness/shape of line for the job, and don’t stress too much on materials. Stay safe, and happy trimming!

James Kennedy