Round Trimmer Line Vs Square: Which One Is Better?

Weed whackers are important tools for maintaining your yard and tackling commercial landscaping projects. One of the reasons they are so useful is their versatility, which is rooted in a trimmer’s ability to take on different attachments.

Round trimmer line is better than square line for most residential needs. This is true in the categories of price, durability, and ease of use. Square line has a better cutting ability, but round line typically does the job for most home owners and residential lawn care professionals.

The trimmer lines are among the variable attachments you can use on a weed whacker, and today we pit two common types against each other to determine the best. So, which is it? Square trimmer lines or round?

Let’s find out.


Square Trimmer Line?

Square lines are among the most popular types of trimmer lines, especially for cutting large swathes of grass and weeds.

The reason you might want to opt for a square trimmer line is the four sharp edges. These edges facilitate cleaner and faster cutting. This is especially beneficial for cutting lawns, as a clean cut minimizes the grass’ susceptibility to infection and pests.

Advantages Of Square Trimmer Line

As we’ve already mentioned, a square line is ideal for whacking excessively thick weeds and grass. You’ll find that you’ll clear such areas much faster with square lines than with round ones.

Disadvantages Of Square Trimmer Line

The main drawback with square lines is their vulnerability to hard surfaces. Do not expect your line to last long if it repeatedly collides with rocks, trees, curbs, buildings, or even fences.

Another negative surrounding square lines is the all-too-frequent jamming that occurs in the spool retainer. You have to take special care when replacing these lines to avoid this problem…but, even then, it may still happen.

One more thing to bear in mind is that square lines tend to be more expensive than round ones since they are a bit more difficult to manufacture. Their strength can also be their weakness.

The sharp edges that do so well cutting rather than ripping through grass blades cause more cost to manufacture and more hang-ups when spooled.

Why Use Round Trimmer Line

Round trimmer lines are perhaps the most common type of line. Most trimmers come with a round line as standard, as these present a well-rounded (pun intended) cut.

These trimmer lines are used for a wide variety of grasses and weeds. They are ideal for light de-weeding and edging lawns because most of the cutting is done by the tip of the line. The lack of edges cause them to be more usable and durable, but also cause tearing of grass blades.

Advantages Of Round Line

The lack of edges is an advantage when it comes to contact with hard surfaces. Round lines are much more durable than square ones in this regard, which means you won’t have to replace them as frequently.

Speaking of replacement, round lines are easier to install too. By virtue of being round, these lines are much easier to fit into a trimmer’s spool retainer without the risk of them flying out.

Additionally, round trimmer lines are more affordable than square lines because they are cheaper to produce. As a result, replacement costs for round trimmers will be lower in the short and long run.

Disadvantages Of Round Line

As far as disadvantages, we cannot overlook the lower cutting quality of round trimmers, especially when compared to square lines. Round lines tend to rip grass rather than cut it cleanly. This is particularly problematic for lawns because ripped grass is vulnerable to pests and infections.

If you are in a rush, using a round trimmer may not be the best way to go. These strings are less efficient at tackling dense grass and weeds than their square counterparts. 

Another disadvantage is that the blunt force of round trimmers on grass and weeds can lead to higher vibration levels for a trimmer. More vibrations will result in quicker wear and tear for the machine.

If you have an electric trimmer and would like the best price for round string, I recommend you get this pack from Amazon.

Does Trimmer Line Thickness Matter?

There are several factors that go into choosing the line thickness for any weedeater string. Does any of it really matter or is it all an advertising gimmick?

Trimmer line thickness really does matter and is dependent on the toughness and thickness of the plants that are to be cut. Thicker line is tougher and able to take down hardier plants. Yet, this thickness comes with a cost, both in expense and difficulty installing it into a trimmer.

There are some general considerations when selecting a string thickness, no matter if it is round or square string. The thickness can make the job easier, but in the wrong machine it can also cause undue strain. Let’s look at thicknesses and their usage.

Weed Trimmer Line Thicknesses By Job Type

Here I will list a basic guide for selecting string. Before getting into this chart it is important to note, most homeowners dealing with simple weeds and yard grasses will be able to choose whatever thickness meets their preference. Even thinner lines have their advantages and will usually tackle anything a residential yard throws at it.

Type Of JobTrimmer String Thickness Range
Residential grasses and weeds0.065″-0.085″
Fields with thicker grasses and plants0.085″-0.110″
Light brush and thick field growthGreater than 0.110″

Keep in mind that the shape of the trimmer line will also impact the needed thickness. Round line has much less cutting ability than square line or others with edges. Yet, when getting square line thickness becomes more important since it inherently is less durable.

Weed Trimmer Line Thickness And Power

Another important consideration of thicker vs thinner string for a weedeater is the weight of the line itself. The thicker the line of course, the heavier it is. This adds more strain to the engine of your trimmer and if it is not powerful enough, this weight can slow the spin of the string.

As you can see, the choice is not as simple as ‘thicker means a better cut’. It is a mix of weedeater power, string shape, and string thickness. Choosing the proper one for your job is a combination of all three of these added to the type of targets you intend to cut.

Does The Shape Of Trimmer Line Matter?

With all of this talk of line shape, edges, and even thickness, how can we be sure that it really makes that much of a difference? How important is trimmer line shape?

The shape of a trimmer line has a lot to do with its durability, cutting ability, and cost to manufacture. Round is the most inexpensive and durable, but it has the least cutting ability. Square and others with edges are more expensive and fragile, but also do the best at cutting.

To answer the question about importance of shape and which you should choose, if you are not sure, round is the way to go. Coming up next I will discuss which is better, round or square. But for those not sure there are really only specific instances that anything, but round will be used for.

If you are not sure if your situation requires other types, then that means you need round trimmer line. You will know when you need others.

To read other articles about lawn care and equipment, see mine here…

Which One Is Better: Square Trimmer Line Or Round?

Choosing between square lines and round ones will mainly depend on the specific advantages you’re looking for, as well as the drawbacks you can live with. Naturally, your circumstances will be a major influence.

Round trimmer line is better for the everyday use on edges and small areas. It is inexpensive, durable, and readily available at most any garden or home improvement store. For most instances it will work as good or better than square trimmer string or any other shape.

Square Trimmer Line Considerations

If, for instance, you have very thick grass and weeds but don’t have a lawnmower, you might opt for a trimmer with a square line. As we’ve already seen, square lines are the better bet for tackling dense grass because of their edges. This edged design allows efficient and rapid cutting along the entire length of the line.

Maintaining the lawn is one of those chores that most people would like to get over and done with quickly. If time is of the essence for you, a square line is the better choice. 

Of course, fitting a line can have a considerable impact on how long it takes to whack your weeds. Many people find the installation of square lines to be a major hassle. These lines are harder to fit into the spool and are known to fly out of position at inopportune times.

As for cost, the cutting efficiency offered by square lines more than justifies their higher purchase price. 

Points About Round Trimmer Line

Round trimmers are better suited for picking off individual weeds and sparse grasses. This is because the most efficient cutting occurs at the tip. As such, a trimmer with a round line is better used as a complement to your lawnmower, rather than as a substitute.

The installation of round trimmer lines is a much more hassle-free affair. You will be up and running much more quickly and with little worry of a dislodged line. 

Another consideration that may tip your decision in either direction is the number of hard surfaces in and around the area you’re working on. Collision with hard surfaces will certainly shorten a square trimmer’s lifespan. Round trimmers are much more durable in this regard.

Durability is also closely related to cost, another major factor for most people. Round trimmers are the more affordable option and, depending on the specific tasks you’re taking on, they are a much better value-for-money choice. Most people will probably prefer lines that are cheaper and more durable. 

Vibrations Can Cause Long Term Wear

If costs are on your mind, you should also consider the long-term effect on your trimmer. The line you choose, combined with your specific tasks and rate of use, can have a direct impact on the vibration levels the machine is subjected to. 

Round trimmers typically result in higher vibrations, which can harm the trimmer in the long run. Square trimmers slice through grass and weeds much more cleanly, which results in lower vibrations. Lower vibrations are better for trimmers, and machines with square lines will likely last longer.

The Final Touches On Round Vs Square Trimmer Line…

The choice of line for many comes down to price, durability, and usefulness. The round line handles all of these with no problem. It is cheap and easy to buy, does most residential jobs with no problem, and lasts longer than edged versions.

The thickness of the round string needs to be considered, but usually thinner string does just fine for most residential lawns and flower bed edging. If you need thicker string you will notice it within a few minutes of trying to cut the area you need trimmed.

Keep in mind, that thicker and more edges is not always better. Thicker string means more weight and requires more horsepower or amps in an engine to spin it at the proper speed. Slower spinning line, no matter the thickness or amount of edges will do a worse job.

Also, edges on string make it highly suseptible to breaking and splitting when any hard surfaces are contacts. Round string takes it in stride whereas square line tends to break.

Hopefully this helps clear up the shape and thickness of round vs square trimmer string. When all else fails, choose round, thinner string. If you need other options, it will be come apparent quickly.

Check out some of these other articles I wrote on similar subjects…


Mathew Booe

Mathew has worked in landscaping professionally for over 10 years. He is a grandpa and frequently interviews other experienced landscapers and lawn care experts who are also grandpas for these articles.

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