How to Put String in a Weed Eater

How to Put String in a Weed Eater

Weed eaters are a great and (in my opinion) an essential tool for homeowners who want to keep their lawn in great shape. However, if you don’t change the string regularly (or correctly) this essential tool will sit idle and simply take up space in your garage. Today, I’m going to explain how to put string in a weed eater. I’ll also cover details about string shape and diameter. Finally, I’ll share my best tips – things I’ve learned from years of using this type of tool on my own property.

Trust and Accuracy Information

This article was last updated on by Lawn Chick Owner Sarah Jameson
Article content reviewed for accuracy by Horticulturist Arthur Davidson, A.S.

To put a new string in a weed eater, you should be sure the power is off, and then clear any debris and release the spool from the trimmer head. Once it is released, you can replace the old string with new weed eater line, which you can buy at any local hardware store. (jump to step-by-step instructions)

Some models have heads that make this process easier, but that isn’t true of all weed eaters.

How to Put String in a Weed Eater

Some Things I’ve Learned

Your trimmer’s owner’s manual will probably tell you the exact length of string the trimmer head can accommodate, but in my experience a quick look at the trimmer head will give you a sense for how much you need to cut and add.

My advice the first time you add string is to guesstimate how much you need. If you have too much, you can certainly trim it to length later. If you start with a short length of string, expect to replace it more often.

Before you replace the string, I recommend that you pay attention to the diameter and type of string you choose for your weed eater (more on that in a minute).

If you want to get an exact match, cut a piece of the old string and take it with you to the hardware store to find a match. Some weed eater trimmer heads will have the recommended size printed on them.

What Is A Weed Eater? (and why I recommend you own one)

A weed eater is a gas-operated or electric tool that uses a rotating string or blade to cut grass and weeds. It is often used as a complement to your lawn mower because it helps you maintain areas on your property that are difficult to mow.

What Is a Weed Eater

I use mine to trim grass around my mailbox and fence posts, tight corners and trees, and even to edge sidewalks, pathways, and my driveway.

On Safely Using a String Trimmer or Weed Eater

Safety is important when using a weed eater. While these tools aren’t as powerful as a lawn mower, they can be dangerous. Be sure to wear protective gear such as gloves and hearing protection while using one. And I absolutely recommend that you wear eye protection as well. I’ve seen small rocks, stems, and even pieces of the plastic spring fly up toward a person’s face more times than I can count. Protect your eyes!

Also, make sure you read the instruction manual that came with your device before you try to operate it or change the string. You’re taking safety risks if you don’t.

One of the most common mistakes I see is people using them in the wrong direction (i.e. walking forward when edging with the tool instead of walking backward).

Make sure the trimmer is off before attempting to change the string, and wear protective gear (eye glasses, gloves).

Aside from changing the string, if you have a gas-powered weed eater, maintaining and checking the oil levels and spark plugs is important for keeping your device working effectively for a long time.

Putting string into a weed eater is an easy task that beginners can complete safely in just a few minutes, but understanding how to do it yourself will make an easy job go even faster.

How Easy Is It To Change String On A Weed Eater?

Changing the string on a weed eater is fairly easy if you have the basic tools and know what you’re doing. In my experience it usually takes no more than 10 minutes, and when you do it correctly, your tool will work just as it did when you bought it.

How Easy is It to Change String On a Weed Eater

Most weed eater models use a spool of string that you can easily replace by undoing the head and removing the old string.

Before you get started, you’ll want to make sure you have a clear workspace so that you don’t lose any parts. You’ll also need a pair of scissors or clippers to cut the new string, and you may want to have a small brush handy to clean debris from the trimmer head.

Once you’ve got all your tools ready, it’s time to start putting in the new string. The process is fairly straightforward, and once you understand the basics, it should only take a few minutes to finish.

When to Change the String on a Weed Eater

Obviously, you’ll need to change the string on your weed eater if it runs low. But you don’t have to wait for that to happen.

When to Change the String on a Weed Eater

Do you use your weed eater quite frequently? It’s a good idea to check the string every few weeks and replace it if necessary.

I check my string after I’ve used the tool and before I put it away. This way if it’s running low, I can get fresh string in there for next time. I don’t know about you, but stopping a job as soon as I start it to do maintenance is frustrating.

It’s better to get in the habit of getting your tool squared away before you put it away so it’s ready to go for next time.

You can cut down on how frequently you need to change the string in your trimmer by avoiding rocks, poles, sticks, and trees when using it. These hard objects are what damage and break the string more quickly.

Changing The String On Your Weed Eater

Always ensure that the weed eater is powered off, and if possible, you should also disconnect the battery.

Changing the String on The Weed Eater

Step 1

After disconnecting the power source of your weed eater, locate the head of your trimmer.

The head of the device often has a locking mechanism that holds the spool in place. You can release this mechanism by pressing a button or turning a knob, and then you’ll be able to access the old string.

On my weed eater it’s a button right on the base of the trimmer head – push and hold and it slides right off in your hand.

Take note of how things come apart, as it’ll make it easier to re-assemble your weed eater when you’re done.

Step 2

Once you’ve removed the head, it should be obvious how to access the old string. In most trimmers the trimmer head is open on the side that seats up into the trimmer.

You can remove and discard the old string (but if you haven’t bought replacement yet, take a piece of it with you to the hardware store to find a match).

Step 3

After the old string is out and you’ve cleared any debris from the trimmer head, measure out a new string length and cut it to size with scissors or clippers.

Every trimmer is a bit different. Some will accommodate extra string and allow you to feed more out as you use it. Others may just take a single piece of string at a time.

If your trimmer can hold a decent length of string, cut 3-4 feet. As you spool it on, if you find that is too much, just trim it down. If you find you could have added more, remember that and next time add a foot.

Step 4

Carefully push the new string into the head. There are typically arrows that show you the direction to thread and spool the string.

Make sure all of the excess string is tucked away so that when the head spins, it doesn’t get tangled up in anything else.

After the new string or spool is secured, you can reassemble the head (usually just push it back into place until you hear the lock click), and you’re good to go.


It’s important to note that every weed eater and string trimmer is a little bit different.

While the guidance provided above should work for most users, I recommend that you read up on the specific instructions for your weed eater model before attempting this task, as some tools have some unique instructions or steps that others don’t.

Factors that May Make Your Weed Eater String Break Early

If you find that your string needs to be changed very regularly, there may be something wrong with the weed eater, or how you’re using it.

Using the weed eater incorrectly or trimming around abrasive objects may cause the string to break.

Factors that may Make Weed Eater String Break Early

It’s normal for the string to need changing after a few months of use, as the string will wear down over time with regular use, but a few simple practices can mitigate this.

Make sure that the string you fit isn’t too long, or you may find that it tangles up, or that you’re just wasting string when the extra length breaks off on first use.

You should also be mindful of where you’re operating the trimmer, as rocks, posts, and other abrasive objects can cause premature wear and tear.

Reducing the wear on your weed eater’s string can reduce the need to change it, saving you time and money.

It’s not a chainsaw, it’s meant for cutting grass and other vegetation.

How To Choose The Right String For Your Weed Eater

When it comes to string types for your weed eater, there are a surprising number of choices for different jobs.

You can also choose various diameters of string or cord for your trimmer.

Here is a look at the different types of string you can use for your weed eater.

Round String

Using round string is the most common option for weed eaters, and it works best with trimmers.

Round String Weed Eater

The shape of the string makes it more resilient against impact when trimming, and it’s also very easy to replace.

As far as durability goes, in my experience you’ll get a lot more miles out of round string than other types of string for your weed eater.

Square String

The square shape of the string makes it ideal for edging along concrete or other hard surfaces. It’s less durable than round string, but it allows you to get a cleaner, sharper cut along the edges.

The trade-off here is that you’ll need to change it more often, as the square shape means it takes more of a beating on impact.

Edged (Cutting) String

Some edges on a string have barbs, allowing it to do a better job cutting weeds and tall grass. You’ve got to use this kind of string carefully, as it may grab onto objects and cause damage if it gets snagged.

Edged Cutting String Weed Eater

But when you use it the right way, an edged (cutting) string can make it easy to cut through thick vegetation.

String With Thicker Diameters (0.080″ to 0.155″)

You’ll find thicker and sturdier strings available, too, which offers extra durability and the ability to cut through tougher vegetation. Its thicker diameter means it’s able to handle more of an impact and will last longer.

This option is great if you have a lot of tough weeds or very large grassy areas to trim, but check to be sure your weed eater can accommodate the extra thickness before you buy it.

String With Narrow Diameters (0.050″ to 0.075″)

The narrow range of string diameters is perfect for light trimming, and it’s possible to get very precise cuts with these strings. They’re also the most economical option; however, you will need to change them more often if you’re using them frequently.

Overall, it’s important to choose the right type of string for your weed eater in order to get optimum results. When in doubt, I recommend you read the instructions and other information that came with your weed eater to find out what that is.

What Are Some Tips For Using Your Weed Eater that Will Help Make Your String Last Longer

Properly using your weed eater can help preserve the string and ensure it lasts longer. Ensuring you have the right string for the job is only half the battle.

Tips For Using Weed Eater

Here are a few tips that can help you get the most out of your string:

  • Be mindful of where you’re trimming and the type of material you’re cutting. Rocks and other objects can cause a lot of unnecessary wear on your string. So, stay aware of where you’re putting your weed eater head. I’ve seen some people try to use weed eaters and string trimmers for cutting into the soil to edge their garden beds or lawn. I recommend using an edger to cut and create the edge, and a trimmer or weed eater to maintain it.
  • Try to avoid trimming around sharp turns, as this can cause the string to break quickly. Instead, adjust your position and keep a straight line whenever possible.
  • Keep an eye on the area you’re trimming. Make sure you don’t accidentally trim over the same spot too many times. This can cause a lot of unnecessary wear on the string.
  • Keeping the head near the ground and level as much as possible will help keep it from bouncing off surfaces. It’ll also keep the string from cutting too deeply into the vegetation.

Preserving the string helps you save money. You’ll get the most out of your trimmer string if you follow the tips I listed above.

Additional Tips for Taking Care of Your Weed Eater

Whether your weed eater is powered by gas or batteries, it’s important to take care of it to get optimal performance.

Follow the tips below for different types of tools to keep your weed eater running smoothly.

Gas-Powered Weed Eaters

Extending the life of your gas-powered weed eater starts with making sure you’re using the right fuel mix. Take a look at the user manual to find out the correct oil and fuel ratio. It’s usually either a 50:1 or 40:1 ratio.

Gas-Powered Weed Eaters

You should also keep an eye out for any signs of wear and tear, such as a worn spark plug or damaged head. Remember to also check the oil level to ensure that the engine runs smoothly and doesn’t overheat.

Battery-Powered Weed Eaters

The battery life of your weed eater will depend on how much you use it and whether or not you run the battery right down to its last few minutes.

Charging your battery up correctly is essential, so make sure you read the instructions for your particular model.

Battery-Powered Weed Eaters

It’s also important to clean the battery terminals on a regular basis to keep them in good condition. If you notice the battery is getting low, it’s better to charge it rather than run it until it quits on you.

Running the battery completely out can damage the battery cells and reduce battery life.

Similarly, you don’t want to let a fully charged battery sit in the charger all the time. Once it’s charged take it out of the charger.

No matter what type of weed eater you’re using, it’s important to take the time to properly care for your machine.

Regular maintenance can help keep it running at its best and will help you get the best results each time you use it.

Final Thoughts on Replacing String in a Weed Eater

If you have a new weed eater and are replacing the string for the first time, it’s easy to feel intimidated. But hopefully, after you’ve read this article, you will feel confident that you know how to change the string on your own.

To summarize, I recommend that you:

  • Check your string level each time you finish using your tool – this way you can replace the string in advance so your trimmer is always ready to use.
  • Use common sense and basic safety – always disconnect the tool’s power source before working on it, and wear basic safety gear (including eye protection).
  • Take a piece of old string with you to the hardware store so it’s easy to identify the correct string-type for your weed eater.
  • Avoid rocks, sticks, and hardscape which will cause your string to break and wear down prematurely.

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Sarah Jameson’s blog, Lawn Chick, is read by over 2 million homeowners each year and she is regularly cited as an expert source of lawn care knowledge by major publications. Her goal is to meet you where you are, and help you achieve a yard you’ll be proud of. Ready to take the next step toward improving your lawn? Grab her free lawn care cheat-sheet: What to Do When - Take the Guesswork Out of Lawn Care, or upgrade your garage by browsing her favorite DIY lawn care products.

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