Ultimate Guide to Trimmer Line

Which trimmer line should you purchase?

Ross writes…

Why shouldn’t I try to cram the “bigger is bad-to-the-bone”string in my trimmer that’s not made for that?

That’s a good question, Ross. And all I can say is “Welcome to America, Pal!”american flag

Bigger, badder, bonier! Why eat soup with a spoon when you can stand in front of a wood chipper with your mouth open, chuck the cans in and enjoy the big, bold flavor?

So what if we get a little aggressive when it comes to cutting down weeds. This great nation of ours was not founded on half-assery.

You think the founding fathers would have bothered to take on King George on a battlefield covered in freakin dandelions? Not in my history book, Frenchie!.

Fighting on crabgrass? As if.

So, you click on Lawnmowerpros.com and to find a trimmer line that will get the job done right. Frankly, anything less than “Chuck Norris” level cutting power is unfit for a American lawn. We don’t want the weeds cut, we want them escorted out of reality with a snap-kick straight to the yonker!

Clearly, this is a job for some .155 gauge Desert Extrusion VS155S4 DESERT VORTEX trimmer line.

Its like trimming grass with a Smith and Wesson!


So, you order the line and then you wait. And by waiting, I mean you go outside every evening as the sun goes down, drink in hand, chip set firmly on your shoulder and you glare at the weeds with a sadistic sneer.

Oh, the sneering. The SNEERING!

“You are so going down, pal.” You whisper through gritted, American teeth. “Down to China town.”


Finally, the trimmer line arrives. You pull all 500 feet out of the box, grab your wire cutters and snip off about twenty feet of line. Thirty minutes of cramming and sweating and growling later, your trimmer head is loaded for bear.

Time to git down.

The engine fires up, you hit the throttle trigger and the trimmer head slowly buzzes to life.

Which is…new.

So you squeeze the trigger harder, but it doesn’t seem to be making a difference. The engine whines and complains all whiny like, but the trimmer head finally starts picking up speed.

“Haa HAAAA!” You screech above the whine of the two cycle engine. “Time to DIIIIEEE weeds!”

Like a bird of prey, the trimmer head dives into the belly of the beast! You crush the throttle trigger, cackling like a mad person as you-


Your lawn trimmer bogs down. It sputters. It…dies.

No trimming, no cutting, no Chuck Norris. Just a sad, dead engine and the stench of defeat.

“Wha-what….I don’t-” You stammer, shaking the trimmer! You adjust the choke, pull the cord, shake it some more but nothing. Slowly, the cold fingers of panic creep up your spine. “No. Noo. NOOOO!”


Can you hear the weeds laughing? I can.


This has been a fictionalized depiction of what happens when you use the wrong trimmer line in your trimmer. Nothing has been changed to protect anyone. In fact, it’s pretty much exactly how it happens. Even with all the swooping and snarling and stuff.

Calm down there Tiger. Everythings ok. Just shut off the trimmer and let’s take a closer look at what’s going on.

The question we’re dancing around here is “Isn’t bigger better?” When the question we need to be asking is “Will bigger get the job done?”

Try cutting kite string with a scalpel. Ping!

Try cutting kite string with a baseball bat. Nah, keep whacking. I’ll wait.


Sure. We could get all scientifiky, but that’ll make my head hurt. So, instead I’m going to break it down like this.

When your engine is running, it moves the trimmer line. This is speed.

The trimmer line has a certain thickness. This is mass.

When the trimmer line hits the grass, the grass breaks. We’ll call this stress.

The grass breaks because the stress is greater than the electromagnetic force holding the molecules together. This is called sorcery and only the “old ones” truly understand it.

For this to happen with any consistency, we need to make sure that the speed is adequate to move the mass to create enough stress to break the grass.


The most significant factors here are: What are you cutting, what are you cutting with, and what are you using to move it?

Your engine is only capable of creating a certain amount of speed. Your equipment manufacturer knew this when they engineered the machine and they have most likely provide information regarding the size of trimmer line that works best on that trimmer.

With thinner line, its easier for the engine to build up and maintain the speed required to work effectively.

Because thinner line has a smaller surface area, it delivers the stress required into a smaller, concentrated spot; causing greater destructive force. For example: A bullet travelling at 2500 feet per second hits the side of a car. It punctures the metal, leaving a hole. A baseball travelling at the same speed hits the side of a car and leaves a dent. A big dent, but a dent none the less.

Trimmers are designed for clearing grass and weeds; not saplings and tubers. If you are running through trimmer line at a record pace, the problem may not be the thickness of the line. You may be using the wrong machine.

And though our American sensibilities prompt us to go bigger, continually upping the thickness of your trimmer line will result in eventual wear and tear on your trimmer. Parts will break. Oh yes… they will.

So, roll it back kids. Consider what you’re cutting, what machine you’re using and whether the two are the best match. When in doubt, check with the manufacturer.


usual suspects

When it comes to trimmer line, sometimes it seems like we keep reinventing the wheel. We’re talking about a piece of plastic that cuts grass here. And yet, there are more variations of trimmer line out there than there are hairs in Donald Trump’s comb over.

So, here’s the stripped down version of all that variety:


Trimmer line come in six standard sizes: .065, .080, .095, .105, .130, and .155. The most common for homeowner use is between .080-.095. Anything larger, and you need to start looking at what your trimmer is rated to use most effectively.



Round line is more than adequate to cut anything your machine is rated to cut. Some folks feel the round line breaks more often. I propose they need to stop cutting so close to the chain link fence. But, I digress.


Square, Pentogonal, Sextogonal. Diamond shaped if you want to take the square line and turn it a little to the left. Edged lines provide a crisper cut, while its new and still has the edge to it. Some folks swear by it, and the manufacturer seems convinced. What we do know is that a cleanly cut blade of grass is a healthier blade of grass, so there may be something to it.


The manufacturer of one of the most popular twisted trimmer lines claims the following are the benefits of using their line. And I quote:

“Less drag” – Drag is a real problem with trimmer line, specifically when the line you are using is too big for your trimmer. I’m still waiting to see exactly “how” twisted line reduces drag. Manufacturers, do you hear me?

“Significant improvement in energy efficiency”– Maybe. Once again, I’m not an engineer. But even if energy efficiency was a relevant aspect of trimmer operation for me, I still don’t think it would matter enough to read the reports; which I’m not sure exist.

broken ear

“50% noise reduction”- This is a relevant issue. Decibel levels for two cycle machines can seriously damage your hearing. And for some reason that only an engineer can explain; the twisted line seems to be quieter than others.

“More impact power”- I have a problem with advertising making unsubstantiated claims like “60% more quality” or “More effective than other brands”. If twisted trimmer line has a direct, and quantifiable effect on “impact power”, show me the numbers and then we’ll talk.

“Decreased vibration”- Shaking is a problem. Shaking tends to expedite the failure of already questionable parts, and we don’t need that. Does the twisted line actually reduce vibration? Don’t know. Try it and let me know what you think.



Plastic trimmer line. Or, as Stihl likes to describe it…“a custom blend of polymers”. Like the custom blend of polymers in my milk jug and my tooth brush I guess. Now, some are stronger than others, but if you know what you’re cutting and what it takes to cut it, you just might end up paying for what you actually need.

Nylon with reinforced core

There are a few types of nylon line with a separate nylon core. The manufacturer implies that this is somehow better than regular, old line. Maybe it is and if you’re inclined to try some out, let me know. However, anyone who suggests that you rig a piece of metal line to your trimmer, kindly tell that stump in the making to go sell crazy somewhere else. It is dangerous, will potentially mess up your trimmer and is, well…just plain dumb. Unless they’re a pirate, and they’re already missing a leg. Even then, you should question their knowledge of the subject. How much weed trimming do they do on a pirate ship anyway?


What we’re saying here is this… it’s important to have the right tool for the job, and the job we’re talking about here is trimming grass and weeds.

You can Americanize the purchase; buy big, buy expensive. There’s a entire industry out there designed solely around the compulsion to do so. Heck, from a retailer stand point…buy as much as you like ! Purchase mass quantities and I will love you like a brother.

Or, you can know your lawn, know your trimmer and “trim” the fat while you trim the lawn.

See what I did there?

Until next time, keep in line.


Do you have questions about trimmer line?  Feel free to contact us via phone, email or the comments section below.


Did you enjoy this article?
Signup today and receive free updates straight in your inbox. We will never share or sell your email address.
I agree to have my personal information transfered to Mad Mimi ( more information )

Bill Brown

Bill is the head of content creation for the LawnMowerPros Blog and DIY section. He’s been in the Outdoor Power Equipment Industry for years and he’s still learning new things everyday. You can often find him creating featured articles, DIY guides, videos, graphics and much more.