How to Put String in a Weed Eater

closeup of string replacement in weed eater

For the places lawn mowers can’t reach, weed eaters save the day. Also known as string trimmers, weed trimmers, or weed whackers, they spin string at high speeds to cut grass and weeds. But what happens when the string is worn out? To get it working correctly again, you’ll need to know how to put string in a weed eater.

This DIY tutorial will provide step-by-step instructions for how to restring your weed eater. Don’t worry — we’ll cover different types of weed eaters so you know what to expect.

10 steps to restring weed eaters

weed eater in action
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Your weed eater’s manual should have specific instructions for your make and model. However, user manuals are easy to lose and aren’t always clear. These 10 steps should work for most models. We’ll cover any variations you may encounter and how you can adjust the steps based on the type of weed eater.

1. Choose the correct replacement string

Weed whacker strings (trimmer line) differ in size, shape, and model. Here are the key features you need to consider:

  • Size: The size or gauge of a string is usually non-negotiable. The most common sizes are .095, .080, and .065 inches. Check the manual to see what size you need – your weed whacker won’t work if you choose the wrong size. A string that’s too big can get stuck, and a string that’s too small is more likely to break.
  • Shape: Most models can use any shape, but round strings are the most common since they’re durable and readily available. However, shapes like twisted, square, star, and serrated trimmer lines cut the grass and weeds rather than tearing them. This cutting power makes them more effective for heavy-duty use.
  • Model: This is the most crucial factor when selecting a replacement string. Most brands specially design strings for their machines. Look up your weed eater model or check your user manual for the right match. This will dictate which size is suitable for your machine. However, generic brands also can work if they’re the correct size.

Note: If you have an auto-feed string trimmer, look for a spool replacement instead of just a roll of string.

2. Measure your string

Once you acquire the new string, you must measure out the correct length. If you use too little, you’ll have to change it sooner. On the other hand, too much string won’t fit inside the spool. Although, you can always trim off the excess.

You generally need 10 to 20 feet of trimmer line, but it would depend on your weed eater’s design and spool size. Check your user manual for the exact measurements for your model.

Models with two strings can either use one long string threaded through or two strings that will wind around the spool next to each other. To get two even strings, hold both ends in one hand, pull on the looped side until you reach the midpoint, then cut.

Pro Tip: You can use your arm span to get the approximate length quickly. Pull the replacement string as far between your two hands (with arms stretched to each side) as possible. If you need 10 feet, do this twice. If you need 20 feet, do it four times. The exact length this will give you depends on your arm span, but it will generally be close enough.

3. Turn off and clean your weed eater

closeup of a weed eater
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It’s unsafe to change the string trimmer line while your weed eater is still on. So, unplug or power it down completely before you open anything up.

You also can take this opportunity to clean your machine. Not only will your string trimmer look tidy, but you’ll ensure the machine isn’t gunked up and malfunctioning.

4. Remove the cap and take out the spool

The string wraps around a spool inside the weed eater’s head. Look for arrows that indicate which direction to turn it or how to line up the lid for removal. Some string trimmer heads have buttons or tabs you need to push inward, similar to a child safety lock on a medicine bottle. When the cap is off, remove the spool.

Watch out for any springs — some are attached, but others are loose and could get lost. If it’s loose, set it aside so you can put it back during reassembly.

Note: Some speed feed trimmers don’t need to be disassembled to change the string. You just need to thread the string through the eyelets. Line up the arrow or line with the eyelets. You should be able to see light from the other side through the hole. That path is where you’ll thread the string (skip to Step 6).

5. Remove any old string

person repairing a weed eater
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Once you take out the spool, you can remove the old line (if there’s any left). Pay attention to where the string is attached and which way it winds around the spool. You can take a picture to help you remember.

If you have an auto-feed weed eater, you will need to replace the whole spool rather than just the string. Don’t worry about attaching the string or winding it up — skip to Step 8.

No string? No worries. Just move on to Step 6.

Note: In some cases, your weed eater may still have enough string, but it’s tangled or damaged. For example, the string trimmer line can melt if the machine gets too hot. You should replace damaged string, but you may be able to untangle and use undamaged string. Follow Steps 6 and 7 to ensure it’s properly attached and wound up.

6. Attach the new string

Depending on the type of weed eater you have, the string trimmer lines may attach differently. For most models, you’ll need to locate the hole or notch in the spool. Then, insert one end of the string so it stays secure. Do this for however many strings your weed eater has.

If you have a speed feed trimmer, thread the string through one eyelet and out the other. Pull it through until it’s an even length on both sides.

7. Wind up the string

Once you’ve attached the string, follow the direction of the arrows to wind up the line. If you wind it the wrong way, the weed eater won’t be able to dispense any string. Wind it up tightly so it fits properly and doesn’t unravel. Remember to leave at least 4 inches of string unwound.

Weed eaters with multiple strings may have numerous channels. Keep each string in its respective channel so they don’t get tangled. For speed feed trimmers, you’ll need to rotate the trimmer head to wind it up.

8. Feed the string through the external holes

When your spool is ready, thread the ends of the string through the eyelet holes in the weed eater, then pop the spool in. It will be too difficult to thread the string through once the spool is in there.

Skip this step if you have a speed feed trimmer — after all, you threaded the string through the eyelets before winding it up.

9. Reassemble the weed eater

man holding weed eater string
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Put the correct side of the spool facing down — it should be labeled accordingly. Remember to position the spring back if it came out earlier. Then, put the cap back on once the spool is in place and the string is through the holes. It should twist or click into place to keep all the components secure.

Note: Speed feed trimmers require no reassembly since you don’t need to take them apart.

10. Pull out the desired length of string

If you followed the above steps, you may already have enough string to get back to weed whacking.

But depending on the type of weed eater, you may need more string. Check for a button on the head that dispenses string when pressed. If you have a bump feed design, tap it on the ground to dispense more trimmer string. Automatic-feed weed eaters will dispense the proper amount without any work on your part.

Note: If there’s too much string or the new lines aren’t the same length, you can trim them down as needed.

FAQ about how to put string in a weed eater

Why do weed eater strings break?

There are several reasons your weed eater string could break, such as:

  • Impact: The string can be damaged if it hits hard objects like fences, benches, concrete, rocks, or walls. Some impact is unavoidable, but you shouldn’t whack the string against objects willy-nilly. Try not to hit these nearby objects to preserve the string as long as possible. Take your time and go just close enough to cut the plants.
  • Dryness: Age or extreme temperatures can make your trimmer string dry out and become brittle. A brittle string can easily shatter and litter your yard with the pieces. To revive it, soak the string in water the day before using it. Remove the old brittle string from the machine and replace it with the new rehydrated string.
  • Incorrect installation: If you wind your string the wrong way, it can dispense incorrectly and break. The solution is to wind it correctly — look for the arrows to serve as your guide.

How do I know if I need to replace the string in a weed eater?

You should replace the string if there’s none left, it won’t come out, it gets caught, or it tangles easily.

How often should I change my weed eater string?

It depends on how frequently you use your weed eater. Most people need to change their weed eater string every three months. You might have to replace the string daily if you use your weed whacker every day. But if you use it sparingly, you may need to change it only once a year.

Of course, the most straightforward rule of thumb is to replace the string whenever it has run out or you have issues.

Why won’t my weed eater bump out more string?

There could be several reasons your string trimmer line isn’t feeding, such as:

  • It’s stuck
  • The trimmer line is the wrong size for your model
  • There’s too much string in the spool
  • The string has melted
  • The string was wound the wrong way
  • There’s no more string
  • The trimmer head, spool cap, or spring is dirty or damaged

What are the best weed eater brands?

The best weed eater brands available today include:

  • Husqvarna
  • Ryobi
  • Homelite
  • Makita
  • Ego
  • Greenworks
  • Black+Decker

For an up-to-date list of recommended models, check out our best string trimmers guide.

Cut yourself some slack and call a lawn care pro

Even if you know how to restring your weed eater, you may not want to do it yourself. After all, who wants to spend their weekend whacking weeds when they can relax? Contact a local Lawn Love lawn care pro, and you won’t have to worry about weed whacking, mowing, or edging.

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Lauren Bryant

Lauren Bryant is a freelance writer currently based in the Pacific Northwest. In her free time, she enjoys long walks and baking. She excitedly awaits the day she can grow her own edible garden.