What Is Better a Square or Round Trimmer Line?

Trimmer Line

String trimmers are the best choice when you want to cut small and unreachable areas of your lawn. Those trimmers use lines to cut the vegetation. Choosing the right type of string is crucial in landscaping your lawn. So, which one is better, a square or round trimmer line?

As part of this debate, the winner was the round trimmer. It is ideal for grass and light vegetation, is more durable than a square trimmer, and will not wear out easily. Overall, it gives you an extended time of use.

Using the wrong string on your string trimmer is a recipe for disaster. In addition, it will make your yard work much harder and more complicated. In this article, we will analyze and compare the pros and cons of square and round trimmers, and explain in detail how to choose the right type.

So, stay tuned!


Square Trimmers: Pros

Square trimmers have sharp edges and cut faster and more efficiently than round ones. The sharp square edges work well with tall, thick, and heavy weeds, as well as with trimmer engines. Plus, they lower the number of vibrations in the engine.

Square trimmers actually cut grass, as opposed to round trimmers. As a result, the lawn appears tidier and cleaner. It’s especially good for thicker and higher vegetation, and is favored by most professionals.

The square string has four edges that cut the grass and more power. Thus, this type of trimmer cuts through thick grass like butter.

Since it’s one of the lowest-priced trimmer lines, it’s very economical.


Square Trimmers: Cons

Even though square trimmers are the best for high and thick grass, they also have a few downsides. They easily break apart whenever they touch stones, curbs, fences, or buildings. Because of their square shape, they’re damaged very easily when you landscape very close to the curb.

They are also very prone to jamming. The strings are known to wrap around the grass and get stuck. You should always use the square string trimmer up from the ground because the grass will pull the trimmer when stuck.

It will wear out much faster than a round line, and you will need to replace the square line more frequently.

Square lines tend to fuse more often than round ones.


Round Trimmers: Pros

Round trimmer lines are most common. They are smooth with no edges and don’t actually cut the vegetation but rather tear it. Because of the smooth surface, the cutting happens on the tip of the line, and when coming in contact with harder surfaces, like concrete or trees, doesn’t break off and gets damaged easily.

Since it doesn’t jam, replacement is very easy and lasts very long, so you don’t have to change these trimmers constantly.

The round line is made of nylon components and is great for private homeowner usage.


Round Trimmers: Cons

Because a round trimmer line doesn’t have edges, it doesn’t actually cut grass but rips it. That’s why your lawn might look a bit uneven.

Round string trimmers aren’t strong enough to cut thicker and higher weeds but only grass and light vegetation. Thus, those are meant for smaller landscaping jobs and tidying up areas next to a curb or tree.

String trimmers, also known as weed whackers, were invented in the 1970s. They function with a little help from the centrifugal force. The line is spun fast enough to be rigid, stiff, and straight because of the centrifugal force, and cuts vegetation.

It’s powered by a gasoline or electric engine. String trimmers are meant to cut unreachable areas of vegetation and finish landscaping.

Finally, trimmer lines are made with different kinds of material and thicknesses, and it’s important to choose the right one.


String Trimmer Line Material

Nylon is the most common material for trimmer strings. It’s available everywhere, but breaks and wears off pretty fast, especially when undergoing harder vegetation cutting and landscaping. That’s why manufacturers started to reinforce nylon with other substances, such as aluminum, in order to make the strings stronger and more durable. But, unfortunately, regular nylon is not the best for heavy-duty landscaping and vegetation cutting since requires you to change the string frequently.

The reinforced nylon is flexible but strong and doesn’t snap easily. Some string trimmers can even work with metal lines. But since most landscaping relies on light trimming, metal lines are unnecessary.

Titanium was the most popular metal for trimmer lines. The cutting power is undeniably better than nylon, and it’s strong and does the job much faster, although the risk is there. Indeed, a metal string can peel off the skin from your body like it peels the bark from trees. Plus, metal strings are much more expensive than nylon ones. After all, with more efficient tools comes a higher price.



String comes in various thicknesses and diameters. The thicker and wider the string, the stronger it is. The standard diameter for most models is 0.080”. If you require a stronger line for more demanding yard work, choose one with a bigger diameter.

If the line is jamming and causing trouble to your trimmer, you should opt for a smaller size.

Line diameters vary from 0.065” to 0.085” for light trimming. That includes very easy jobs, like trimming the edges on your lawn.

For thicker grass, 0.085” to 0.110” is sufficient. When the grass has already grown for a while, it’s thicker and heavier.

When it comes to professional and harder work, you should go for lines thicker than 0.110”. It should be used on out of control wild vegetation that is higher than an average person. You wouldn’t need this diameter for personal use.

Finally, it’s always best to check the manufacturer’s recommended size for your strings before choosing it on your own.


Welding Resistance

Welding is a process that involves heat, which starts to interact with the material. Sometimes, a trimmer comes in contact with an obstacle, such as a fence or concrete curb. As the line is moving at a very high speed, when it’s in contact with another surface, it creates a lot of heat.

Heat causes the string to melt and weld, causing trouble inside the spool of the trimmer. When that occurs, you have to remove it and put a new string. Some strings are made of materials with a higher heat resistance than others, but in general, square lines are more weld-resistant than round ones.

Round lines have a small surface, which causes the heat to build up very quickly and melt the lines.

When removing the welded lines, be very careful as the cleaning process is not easy, and it tends to be very hot.


How to use a string trimmer

String trimmers are the perfect tool to tidy up your lawn around fences, trees, and curbs. They’re usually used as the final step in landscaping. However, they often get misused, so we will quickly explain the most important things to keep in mind when using the popular weed whacker.

Tip: Always read the manual instructions before using a string trimmer.


  1. Choose Your Trimmer Type

Before choosing the type of trimmer and trimmer line you want to use, you should analyze and find out what type of vegetation you are dealing with. Lawn size should be kept in mind as well.

For example, if you have a large yard with thick grass, you should opt for a gas square line trimmer because it has more power than a round one and can manage your yard. For lighter vegetation, a cordless round line trimmer would be a great investment.

  1. Protect Yourself

Clear rocks, larger pieces of wood, and other debris are obstacles that could be potentially dangerous when using a string trimmer. Thus, you should always wear protective gear when using string trimmers. Eye protection is a must, so choose clear eyewear. You can also add a hat. Finally, gloves are also necessary to protect your hands.


  1. The Process

Grab the trimmer firmly. It shouldn’t be too heavy to handle. Don’t hold it directly above the soil as the strings can cause scarring and damages.

Hold the trimmer slightly above the grass at a slight angle. It should be angled in order to cut and trim efficiently.

  1. Maintain Your String

Take good care of your gardening tools, and they will reciprocate and serve you for a long time. Well-maintained gear lasts longer and comes with fewer malfunctions. Whenever you see some string damage, you should replace it right away.

A damaged string is almost certainly going to break soon and can cause a malfunction of the engine. First, you will have to remove the spool on your trimmer. It’s the part that covers the trimmer’s head.

When removing it, you should cut a new piece of string in a desirable size, preferably about 8 feet. When you install the new piece of string through the holes on the trimmer’s head, make sure the ends are of even length.

Pre-cut lines exist. They are already cut and sized perfectly, so you don’t have to worry. After all, convenience is the key for keeping things simple.

Then, secure the ends, put the spool back on, and you’re ready for landscaping!


Safety First

In string trimmers, the line moves at a very high speed to cut the vegetation. In contact with rocks, trees, or pieces of debris, broken-off pieces can travel at a very high speed and become dangerous. They can damage cars, buildings, and even passersby. Trimmers with metal strings are actually unwanted, even forbidden in some countries following fatal incidents.

Safety glasses or any kind of suitable eye protectant are the most important part of your safety gear. Gloves are also mandatory. Many strings are manufactured in neon easily-spotted colors to remove parts of the string if it breaks off successfully.

Some people buy green strings for their trimmers to make them unnoticeable in the grass and vegetation, and just leave them if they break off.

The major dilemma with nylon lines for trimmers is pollution. Indeed, although plastic is very bad for the environment, it’s the most effective material. Metal lines are very dangerous even though they’re a more ecological option.

Animals can ingest the plastic line and could be at risk of injury or even death. Plus, plastic takes a very long time to break down, and your lawn could be full of microscopic plastic particles. Trimmer lines tend to dry out and become brittle over time. Some manufacturers, like Stihl, make their trimmer lines hygroscopic. That means the lines absorb and trap moisture, so they last longer.

But a great tip is to keep your lines soaking in water from time to time. Doing so will prevent the line from drying out and will make it more flexible.

Still, only string trimmers are the ones that give your yard a well-maintained, tidy look.


What Shape Trimmer Line Is Best?

All things considered, we will now determine whether a square or round line is better for your trimmer.

Trimmer lines are an important component in landscaping and their use depends on different factors. The size of your lawn and the type of vegetation are the main parameters.

If you have light grass around residential areas, round line trimmers are your best bet as they’re much more efficient and won’t break or wear down as quickly as square lines.

But, if you’re up against thick and heavy vegetation, a square line is better. It’s ideal for professional landscapers and industrial areas. It’s efficient but could break in contact with concrete, fences, or trees.

Meanwhile, round lines are very durable against obstacles and debris. Because they don’t have edges, they tend to bounce off the surface they hit, which explains why their durability and resistance.

Round lines are also cheaper than square ones. If you keep in mind that you will have to change your square line more frequently than your round line, from the economic point of view, the round line is definitely the best choice.

Besides, square lines have four edges. Even though the edges cut the grass perfectly, they tend to wear down quicker. With every use, they get more damaged, and could easily break when in contact with a rock or curb.

Plus, they can get jammed very easily and stuck inside your engine. It can cause many problems and can even damage the engine when trying to remove the jam.

Meanwhile, round strings are simple and durable. Their replacement is very easy, although you won’t have to do so often. Since they’re meant for general use, they should last longer if you light landscaping with minimum vegetation.


They are mostly made of a nylon mixture and are great for homeowners.

From an aesthetic point of view, square lines create a sharper and cleaner cut. The yard looks tidy, and people enjoy it. However, round lines don’t actually cut vegetation; instead, they rip it, creating an uneven look.

A round string trimmer is likely to overheat, and the lines might fuse because it can stand against concrete, but a square line is the best choice for overgrown yards.

Weed whackers are noisy tools that are sometimes difficult to handle because of the vibrations. With their edges, when turning at high speed, square lines make a lot of noise and cause a lot of vibrations.

On the other hand, round lines are smooth. Although a round line trimmer can make a lot of noise as well, the vibrations and feel when using it are much more appreciated.

With all this in mind, and considering the price, efficiency, longevity, and overall safety of each option, the round line is a winner in this category.

Although, keep in mind that this article focuses on the general, residential use of trimmers, for which round line trimmers are definitely the best choice. Their durability is a more important factor than their beauty and design.

However, it’s important to say that a trimmer line can be used in many different kinds of trimmers, and does not provide the same experience to everyone. Some trimmers get huge improvements in their performance or durability, while others often encounter more problems and malfunctions.

A trimmer is a vital piece of home tools. Choosing the best line for your trimmer defines your yard work. You should remember every aspect – from the economy and durability to the cut effectiveness, vegetation type, line size, and weld resistance.

Finally, it is crucial to read and consider the manufacturer’s recommendations before choosing a particular string.

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