The basic process: wind new string onto the spool

To change weed eater string, you remove the spool from the head, unwind the old string, wind new string onto the spool in the correct direction, and reinstall it. The whole job takes about five minutes once you know where the release button is. Most weed eaters use the same general design, though the exact button location and spool shape vary by brand.

You do not need tools beyond what comes with the machine — usually just your hands and sometimes a small screwdriver. The hardest part is winding the string tight enough that it does not slip, but even that becomes automatic after the first time.

Key Takeaways

  • The spool release button is usually on top of the weed eater head; press it to pop the spool out.
  • Wind new string onto the spool in the direction the arrow on the spool points, keeping tension as you wind.
  • Leave about 6 inches of string loose on each side so the trimmer head can feed it out as you use it.
  • Reinstall the spool by pressing it back into the head until you hear or feel it click into place.
  • If string does not feed out when you tap the head on the ground, the string may be wound backwards or too loose.

Locate and remove the spool

Look at the round head at the bottom of your weed eater. On top of it, you will see a button, usually plastic and slightly raised. This is the spool release button. Press it firmly — you may need to press harder than feels natural — and the spool will pop out toward you.

If you cannot find a button, check the sides of the head. Some models have a release tab instead of a button, or the button may be recessed. Your owner's manual will show the exact location if you are stuck, but most buttons are obvious once you know to look for them.

Once the spool is out, set it on a flat surface. You will see old string wound around it, usually in a figure-eight pattern or in a spiral groove. Some of this string may still be attached to the head itself; that is normal.

Remove old string and clean the spool

Unwind the old string from the spool by hand. You do not need to remove every last bit — just get the bulk of it off so you have a clean surface to wind new string onto. If the string is stuck or brittle, a quick pass with your fingers or a soft brush will loosen it.

Look at the spool itself. You should see an arrow printed or molded into the plastic, pointing in one direction around the spool. This arrow shows you which way to wind new string. Write it down or take a photo if you think you might forget — winding backwards is the most common mistake and will prevent the string from feeding out.

Wind new string onto the spool

Buy replacement string that matches your weed eater's diameter — usually 0.065 inches, 0.080 inches, or 0.095 inches. The package will say what size it is, and your owner's manual will tell you what your machine needs. Using the wrong diameter can jam the head or cause the string to slip.

Cut a length of string about 20 to 25 feet long. Insert one end into the small notch or hole at the edge of the spool — most spools have a slot designed to hold the string while you wind. Hold the string with slight tension in one hand while you wind with the other, following the arrow direction. Wind tightly and evenly, keeping the string from overlapping itself.

Wind until you have about 6 inches of string left loose. Do not wind it all the way — the trimmer head needs loose string to feed out as you use it. If you wind too much string onto the spool, it will jam and not feed properly.

Reinstall the spool into the head

Look at the center of the spool. You will see a post or shaft that fits into the head. Align the spool so this post slides straight into the opening in the head. Push the spool in firmly until you feel or hear a click — this means the release button has caught and locked the spool in place.

Give the spool a gentle tug to make sure it is seated. It should not move. If it spins freely or feels loose, remove it and try again. The click is important — without it, the spool can come loose while you are trimming.

Feed string through the head openings

Most weed eater heads have two small openings or eyelets where string comes out. Pull the loose string you left on each side and thread it through these openings. You should now have two lengths of string hanging down from the head, each about 6 inches long.

If your head has only one opening, thread both ends through the same hole. The exact setup depends on your machine, but the goal is the same: get the string positioned so it can spin and cut.

Test the string feed

Hold the weed eater with the head pointing down and gently tap the head on the ground a few times. This tapping motion triggers the automatic feed mechanism on most machines, which should pull out a small amount of new string. If nothing happens, the string may be wound backwards, wound too tightly, or not seated in the feed holes correctly.

If the string does not feed, remove the spool again and check the arrow direction. Rewind if necessary. If it still does not work after rewinding, the feed mechanism itself may be worn, but that is rare on newer machines.

Frequently Asked Questions

How much does replacement string cost?

A spool of replacement string usually costs between $5 and $15 depending on the brand and package size. Buying a larger spool is cheaper per foot than buying small pre-wound spools, though you will need to wind it yourself. Most homeowners find they replace string once or twice per season.

Can I use any brand of string in my weed eater?

You need to match the diameter, but the brand does not matter. A 0.080-inch string from any manufacturer will work in any machine that takes 0.080-inch string. Stick to the diameter your manual specifies — using a thicker or thinner string can cause feeding problems or damage the head.

What if I wind the string backwards?

The string will not feed out when you tap the head on the ground. Remove the spool, check the arrow direction, and rewind it the opposite way. It is a common first-time mistake and easy to fix.

How tight should I wind the string?

Wind it firmly enough that it does not slip when you tug it, but not so tight that you strain your hand. The string should be snug against the spool with no gaps, but you should still be able to wind it smoothly without the spool flexing. Tension comes from holding the string steady as you wind, not from squeezing the spool.

Why does my string keep breaking?

String breaks when it hits rocks, thick weeds, or hard ground. Worn or damaged string also breaks more easily. If you are breaking string constantly, check that you are using the correct diameter and that the feed mechanism is not damaged. Hitting softer targets like grass and thin weeds will extend string life.