Replace the cord yourself in 15 minutes with basic tools

Replacing weed eater cord is a task you can do at home without special equipment. Most trimmers use one of two designs: a fixed spool that you wind by hand, or an automatic head that advances cord as you tap it on the ground. The steps differ slightly between them, but both take about 15 minutes once you have the right cord diameter for your model.

The cord itself costs between $5 and $15 for a spool large enough to replace it several times. You will need scissors or a utility knife, and possibly a screwdriver depending on your trimmer's design. Before you start, check your trimmer's manual or the label on the head to find the correct cord thickness — usually 0.065 inch, 0.080 inch, or 0.095 inch — because using the wrong size can jam the head or break the cord under load.

Key Takeaways

  • Cord diameter matters: check your trimmer's manual or the label on the head to buy the right thickness, usually 0.065, 0.080, or 0.095 inch.
  • Fixed spools require you to wind the cord by hand in a specific pattern, while automatic heads let you load a straight length and tap to advance it.
  • The entire job takes 15 minutes and requires only scissors, a utility knife, and possibly a screwdriver.
  • Winding too tightly or leaving the cord uneven causes jams and breakage, so take time to lay each wrap flat and keep tension steady.
  • Most trimmers use cord sold in bulk spools at hardware stores, garden centers, and online retailers for $5 to $15.

Identify your trimmer head type before you buy cord

Weed eaters fall into two main categories: fixed-spool heads and automatic advance heads. A fixed-spool head has a plastic spool visible inside the trimmer head, with two eyelets or slots where the cord exits. An automatic head is a sealed unit with a single eyelet and a small button or bump on the bottom. Knowing which you have tells you how to load the new cord and how much you need.

Fixed-spool heads require you to wind the cord onto the spool yourself, usually in a figure-eight or spiral pattern. Automatic heads come with a pre-wound spool inside; you load a straight length of cord into a slot, close the head, and the mechanism advances it as you tap the trimmer on the ground. Check your trimmer's manual or look at the head itself — the design is usually obvious once you know what to look for.

Remove the old cord from a fixed-spool head

Unscrew the center bolt or cap on the trimmer head using a screwdriver or by hand, depending on your model. Most heads have a single bolt in the middle; turn it counterclockwise until it comes free. Lift off the plastic cover and remove the spool underneath. If the old cord is still wound on it, you can unwind it by hand or cut it away with scissors.

Once the spool is bare, set it aside. Inspect the spool for cracks or warping — if it is damaged, you may need to replace the entire head rather than just the cord. Most spools are durable and reusable, so you will use the same one again. Clean out any grass or debris from inside the head housing before you load the new cord.

Wind new cord onto a fixed-spool head correctly

Cut a length of cord about 20 feet long to start. Most fixed-spool heads use a figure-eight or side-by-side winding pattern. Check your manual for the exact pattern, but the most common method is to wind the cord back and forth across the spool in parallel lines, keeping each wrap tight and flat against the previous one. Start at one end of the spool and work toward the center, then reverse direction and fill the other half.

Keep steady tension on the cord as you wind — not so tight that you strain the spool, but tight enough that the wraps do not slip. Leave about 6 inches of cord free at each end; these will thread through the eyelets to become the cutting lines. Once the spool is full, thread one end through each eyelet, then reassemble the head by placing the spool back in the housing, aligning the cord ends with the eyelets, and screwing the center cap back on.

Trim the free ends to the length recommended in your manual — usually 8 to 10 inches. If the cord is too long, it will hit the guard and wear quickly; if it is too short, you lose cutting width. Test the trimmer on a small patch of grass to make sure both lines feed evenly and the head does not vibrate.

Replace cord in an automatic advance head

Automatic heads are faster to reload because you do not wind anything. Locate the slot or opening where the cord feeds into the head — it is usually on the side or bottom. Some heads have a removable cover you unscrew; others have a slot you access directly. Remove any old cord still in the head by pulling it out or cutting it away.

Cut a new length of cord about 15 to 20 feet long. Insert one end into the slot as far as it will go, usually until it hits a stop or catch inside the head. Close the cover or cap and screw it tight. The other end of the cord will hang free; trim it to about 8 to 10 inches. When you tap the trimmer head on the ground during use, the internal mechanism will advance the cord automatically, so you do not need to wind or adjust anything manually.

Test the new cord before full use

Start the trimmer and let it run for 30 seconds without cutting anything. Listen for unusual vibration or noise, which can mean the cord is wound unevenly or the head is not balanced. If the trimmer sounds normal, test it on a small patch of grass at low speed. Both cutting lines should feed evenly and cut at the same height.

If one line is shorter than the other or the head vibrates, stop and check your work. For fixed-spool heads, the problem is usually uneven winding — unwind and rewind the affected side. For automatic heads, make sure the cord is seated fully in the slot and the cover is tight. Once both lines feed evenly, you are ready for normal use.

Frequently Asked Questions

What happens if I use the wrong cord diameter?

Cord that is too thin will break under load and require frequent replacement. Cord that is too thick will not fit through the eyelets or will jam inside the head. Always check your trimmer's manual or the label on the head for the correct size before you buy.

Can I use any brand of trimmer cord?

Yes. Trimmer cord is a standard product sold by most hardware stores and garden centers under various brand names. The only thing that matters is the diameter. Nylon cord from any manufacturer will work as long as it matches your trimmer's specification.

How often do I need to replace the cord?

It depends on how often you use the trimmer and the thickness of the vegetation. Light residential use might mean replacing cord once or twice a year. Heavy use or thick weeds can wear it out in a few weeks. You will know it is time when the lines become noticeably shorter or fray at the tips.

Do I have to replace the entire spool on a fixed-spool head?

No. The spool is reusable. You wind new cord onto the same spool each time. Replace the spool only if it is cracked, warped, or the eyelets are damaged.

Why does my automatic head not advance cord when I tap it?

The cord may not be seated fully in the slot, or the internal mechanism may be jammed with grass or debris. Remove the cover, clean out the head, and reload the cord, making sure it goes in as far as it will go. If the head still does not advance, the internal mechanism may be broken and the head may need replacement.