How Long Should My Trimmer Line Be?


While trimming your yard, you may be on the lookout for ways to speed up the process and get more work done in a shorter period. Is a longer trimmer line the solution you’ve been looking for? What is the optimal line length for your trimmer that yields the best and quickest results? 

Here we have to make a distinction between the “visible” part of the line, and the spool that goes into the trimmer’s head. 

The optimal line length for each trimmer varies, which is dictated by a mark on the guard. Removing the guard and increasing the length of the line beyond its optimal limit will cause decreased performance and efficiency. It will also reduce the lifespan of the trimmer. 

If we are talking about the length of the line that goes into the trimmer head, anywhere from 10 to 25 feet should be fine. As a general rule, don’t try to add more line to the trimmer’s spool than it can take. If you managed to cut a line longer than that by accident, you can always shorten it later. 

Keeping the trimmer line length within the recommended guidelines is essential to keep your trimmer running for years. I’ve gathered all the details about the length of the trimmer line and the disadvantages of a longer line below. 

The Ideal Length for Your Trimmer Line

String trimmers are optimized to work best at a specific line length. A mark on the guard dictates this length. Most guards also have a blade that ensures the line never exceeds this length and cuts off any excess. 

However, you may consider removing the guard and blade and increasing the line’s length. The longer line will be able to cut more grass and weeds in a shorter period.

The increased cutting ability comes at the expense of your trimmer’s lifespan and decreased efficiency and performance because a longer line will cause the engine to overwork and heat up. 

You could either keep the guard on and use the ideal line length for your trimmer or take it off and increase the length by a couple of inches. I’d like to stress that I do not recommend taking the guard off unless you are absolutely sure what you are doing!

Length With Guard On 

Leaving the guard on will protect your trimmer from overworking. It can increase its lifespan, and you won’t have to worry about repairing or buying a new trimmer. 

Most string trimmers have a cutting diameter of 10-15 inches, meaning that the optimal line length will be about half of that, minus the central part of the trimmer head.

Most guards are equipped with a discreetly placed blade that cuts off the excess and prevents the line from getting too long. This means that you don’t really have to worry about your line being too long as there is no way to get it wrong as long as the trimmer guard is in place and its blade is sharp enough. 

This is one of the main reasons why most people recommend keeping the guard on at all times. I wrote about this in more detail here

Length With Guard Off 

After removing the guard, you can bump as much line as you want. A longer trimmer line will widen the cutting area and allow you to cover more ground. So you can complete your task quicker! 

However, the longer wire will reduce the cutting power and efficiency if your trimmer isn’t strong enough to handle the increased line length. You may end up with a yard that isn’t as neatly cut as you hoped! 

Furthermore, using your trimmer like this usually requires a thicker trimmer line – maybe thicker than what your machine can take. There is a reason why you mostly see lawn care professionals using trimmers in this way. 

Four Disadvantages of a Longer Trimmer Line

Removing the guard and increasing the line length will increase your cutting ability. But at what cost? 

Here are four disadvantages of a long line: 

1. Decreased Cutting Power 

Trimmers require a lot of power from their engines to work efficiently. Advancing too much line requires even more power, causing the engines to overwork.

They may be unable to deliver the necessary power resulting in lower RPM (rotations per minute). So, the longer line will cover more area but have decreased cutting power and perform the job poorly. Your yard may not end up looking as neat as you wanted.

2. Engine Overheating 

Since the engine is working twice as hard than normal, they generate twice the heat. The cooling system of the trimmer will be unable to dispense all this excess heat and cause the engine to overheat. 

This may eventually cause engine failure, and you may have to replace the trimmer.

3. Increased Vibrations 

Manufacturers design trimmers in a manner that they can only work best with a particular line length. 

Crossing the intended limit will overwork the engine and increase vibrations, making the trimming experience uncomfortable and more tiresome. 

4. Frequent Line Breaks

A longer line will get stuck in fences, flowerbeds, and trees. It will frequently break, and you will constantly need to advance more lines. Moreover, you will end up wasting a lot of time spooling in new lines as the old one breaks and runs out quickly. 

I have summarized the four disadvantages of using a long line and their effects below. 

Disadvantage Effect
Decreased Cutting Power  Poor performance and untidy yard. 
Overheated Engine  Engine failure. 
Increased Vibrations  Uncomfortable trimming experience.
Frequent Line Breaks The line runs out quickly and needs to be frequently replaced. 

Alternatives to Longer Trimmer Lines

Longer lines are inefficient and harmful to your trimmer. Fortunately, they are not the only way to get a quicker cut. 

You can get a thicker line that is twisted in shape and made out of high-quality materials. Such lines boost the performance of your trimmer. They are also durable and long-lasting. So, you can save tons of time as you won’t have to spool in a new line constantly. 

If all else fails and you feel like you need more cutting power, you can try buying a trimmer that has a larger cutting diameter. The difference between 10 and 15 inches can be huge!

Final Thoughts

Using the optimal line length recommended by the manufacturer will enhance your trimming experience. It will also boost the trimmer’s performance and yield a cleaner cut and a cleaner yard. If you want a little boost, you can always get a thicker twisted line made of high-quality materials that get the job done faster! 

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!

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