The basic steps to replace your weed eater string

Replacing weed eater string takes about 10 minutes once you know the process. First, unplug the machine or remove the battery so it cannot start while you work. Then locate the spool — the plastic bobbin that holds the string — usually at the bottom of the head. Most spools twist off counterclockwise by hand, though some require a small flathead screwdriver to release a clip. Once the spool is out, remove the old string completely, clean out any debris, and measure the length of new string your machine needs (check your manual or the spool itself for the length, typically 30 to 40 feet). Wind the new string tightly and evenly onto the spool in the direction marked by an arrow, feed the ends through the eyelets on the head, and screw the spool back in. The whole job is mechanical — no special tools or skills required.

The most common mistake is winding the string too loosely or in the wrong direction, which causes it to unwind during use. The second most common is using the wrong string diameter for your machine. Check your manual for the exact diameter (usually 0.065, 0.080, or 0.095 inches) because using thicker or thinner string can jam the spool or break too easily.

Key Takeaways

  • Always unplug the machine or remove the battery before opening the spool to prevent accidental starting.
  • Wind the string tightly and evenly in the direction shown by the arrow on the spool, or it will unwind during use.
  • Check your manual for the correct string diameter — using the wrong size can damage the spool or cause the string to break.
  • Feed the string ends through the eyelets on the head before screwing the spool back in, or the string will not cut properly.
  • Most spools twist off by hand, but some models have a clip that requires a flathead screwdriver to release.

Locate and remove the spool

The spool sits inside the cutting head at the bottom of the weed eater. On most models, you can remove it by gripping the spool firmly and turning it counterclockwise — it will unscrew by hand without tools. Turn slowly and steadily; if you feel strong resistance, stop and check whether a clip or latch is holding it in place instead.

Some machines, particularly commercial or heavy-duty models, have a small clip or button on the side of the head that you must press or flip before the spool will come free. Look around the base of the spool for a small lever or clip. If you find one, press or slide it while turning the spool. Once the spool is loose, pull it straight out and set it on a clean surface.

Remove the old string and clean the spool

Pull out any remaining string from the spool by hand. If the string is stuck or wound very tightly, use a flathead screwdriver or old butter knife to gently pry the end loose. Once the string is out, wipe the spool with a dry cloth to remove grass clippings, dirt, and old string fragments. Pay special attention to the grooves where the string winds — debris here can prevent new string from sitting flat.

Check the spool for cracks or damage. If the plastic is cracked, warped, or has deep gouges, the spool should be replaced rather than refilled. A damaged spool will not hold string evenly and may cause the string to break repeatedly or jam.

Measure and prepare the new string

Look at the spool itself or your machine's manual to find the correct string length. Most residential weed eaters use 30 to 40 feet of string per spool. Some spools have a line marked on them showing where to cut — if yours does, use that. Otherwise, measure the length with a tape measure or unwind string from the spool until you reach the recommended length, then cut it with scissors or a utility knife.

Check the string diameter before you start winding. The most common sizes are 0.065 inches (thin, for light grass), 0.080 inches (medium, for most residential use), and 0.095 inches (thick, for heavy weeds and brush). Using the wrong diameter can cause the string to jam in the spool, break too easily, or not feed properly. Your manual will specify which size your machine needs.

Wind the string onto the spool

Look for an arrow printed or molded onto the spool showing the direction to wind. This direction matters — if you wind against the arrow, the string will unwind as you use the machine. Hold the spool in one hand and feed the string into the first groove or notch with your other hand. Wind the string tightly and evenly, keeping tension so each wrap sits flat against the previous one. Do not let the string bunch up or overlap itself.

Wind until you reach the end of the spool or until the string fills the grooves completely. Leave about 6 inches of string unwound at the end — you will feed these ends through the eyelets on the head. If you wind too much string, it will jam when you try to screw the spool back in. If you wind too little, the machine will run out of string quickly.

Feed the string through the eyelets and reinstall the spool

The cutting head has two small holes or eyelets, usually on opposite sides. Take the two loose ends of string and feed one end through each eyelet. Pull the string taut so it does not slip back into the spool. The string should stick out about 4 to 6 inches from each eyelet — this is the cutting length. If the string is too short, pull more out from the spool before screwing it back in.

Align the spool with the head and screw it back in by turning clockwise. Turn firmly but do not force it — you should feel steady resistance as the threads engage. Once the spool is seated, give it a final quarter-turn to may support it is tight. If your machine has a clip or button, make sure it clicks back into place. Plug in the machine or reinstall the battery, and test the string by running it briefly at low speed to confirm it feeds and cuts evenly.

Troubleshooting common problems after replacement

If the string does not feed out when you start the machine, the spool may be wound too tightly or the string may not be seated properly in the eyelets. Stop the machine, unplug it, and check that both string ends are fully inserted through the eyelets and pulled taut. If the string is still stuck, remove the spool again and unwind a few loops to reduce tension, then reinstall.

If the string breaks when ready or within the first few minutes of use, you may have used the wrong diameter or wound the string too tightly. Check your manual for the correct diameter and try again with a looser wind. If the string unwinds as you use the machine, you wound it in the wrong direction — remove the spool and rewind following the arrow on the spool.

If the string is uneven or one side is longer than the other, the spool may not be seated evenly in the head. Remove it, check that the threads are clean and aligned, and reinstall, making sure it sits flush. Uneven string will cause vibration and poor cutting.

Frequently Asked Questions

How often do I need to replace the string?

This depends on how often you use the machine and what you are cutting. Light residential use may require a new spool every few months, while heavy use or thick weeds can require a new spool every few weeks. You will know it is time when the string becomes noticeably shorter, breaks frequently, or stops feeding out.

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

You can use any brand as long as it matches the diameter your machine requires. The brand does not matter — what matters is the diameter. Buy string in bulk from hardware stores or online; it is inexpensive and lasts a long time if stored in a cool, dry place.

What if my spool is stuck and will not unscrew?

Try wrapping a rubber band or cloth around the spool for better grip, then turn slowly and steadily. If it still will not budge, explore a small amount of penetrating oil (like WD-40) around the threads, wait 10 minutes, and try again. Never force it — forcing can crack the spool or strip the threads.

Do I have to wind the string by hand, or can I buy pre-wound spools?

Most machines sell pre-wound replacement spools that you straightforward screw in and use. These cost more per use than bulk string but save time. Check whether your machine model has pre-wound spools available before you buy — not all models do.

Why does my string keep breaking?

String breaks most often because you are using the wrong diameter (too thin for the job), winding it too tightly, or hitting hard objects like rocks or concrete. Check your manual for the correct diameter, wind more loosely, and try to avoid solid obstacles. Thicker string (0.095 inches) is more durable than thinner string (0.065 inches) but uses more fuel.