How to Load String into a Cordless String Trimmer

Before you start: safety and prep

Take the battery out of the trimmer before you touch the head. A pack that is still seated can start the motor if the trigger is bumped, and the spinning head can cause a serious cut. Set the battery well away from your work area.

Wear safety glasses and work gloves. Old line can snap or spring out of a spool, and bits of dried grass and grit tend to fly off the head. Work on a flat surface such as a workbench or a patio table, and lay the trimmer down so it cannot roll.

• Remove the battery and set it aside.
• Put on safety glasses and gloves.
• Check the manual or the label on the head for the correct line diameter.
• Have scissors or a line cutter ready.
• Have a small brush or rag handy to clean out the head.

Pick the right line

Line diameter matters. Too thick and it will not feed through the eyelets or fit the spool. Too thin and it breaks quickly on tough weeds. Your trimmer's manual or the print on the spool cap tells you what to buy.

Our published specs show how much this varies. The EGO ST1502SA lists 0.095 in line for tougher weeds, while the goodjob GB-DST26A-2MG lists 0.065 in line. Those two heads are not interchangeable, so always match the diameter for your own model rather than assuming.

Also check the line shape and the spool design. Some spools take a single long strand folded in half, and others take two separate pieces. Pre-cut line sold for your brand is fine if it matches the diameter and the head type.

Know your head type first

Cordless trimmers use a few different heads, and the loading method depends on which one you have. Look at the bottom of the head for a button, a bump knob, or just a plain cap.

Our best cordless string trimmer page notes which models use auto feed and which use bump feed, so it is a quick way to confirm what kind of head your model has.

Step by step: replacing the line

These steps cover the most common spool-style head. Your head may differ in small ways, so compare them with the diagram in your manual.

• Press the tabs or turn the cap to release it, then lift the cap off. Note how the spring and any other small parts sit so you can put them back the same way.
• Pull the spool out and throw away any old line left on it. Clean dirt and grass out of the housing.
• Cut a length of new line. Your manual may give a length. If it does not, cut enough to fill the spool without overfilling it.
• If the spool has a center divider, fold the line in half and hook the fold into the notch. If it has a single hole, push the end through it to anchor it.
• Wind the line onto the spool tightly and evenly, in the direction of the arrow on the spool. Winding the wrong way is the most common reason line will not feed.
• Leave a few inches of each end free, and secure them in the small slots on the spool edge if your spool has them.
• Thread the loose ends through the eyelets on the head housing, then set the spool back in place.
• Pull the ends gently as you press the cap on until it clicks or locks. The line should slide out of the slots as the cap seats.
• Reinstall the battery only when the trimmer is set down and ready to use.

Loading quick-reload and auto-feed heads

Some heads let you skip the spool entirely. EGO's listing for the ST1502SA says its Rapid Reload head is designed to load new line quickly and easily, so follow the head's printed diagram and the manual for the exact method.

Auto-feed heads need a little extra attention. The HortiHub listing says its auto-feed system releases 0.4 to 0.5 inches of line when you start the trimmer, and it asks you to extend the line to 6 inches before first use. That is a good reminder to check your manual for a starting length before the first run.

With auto-feed heads, an overfilled or tangled spool can stop the line from advancing. If the line will not come out, take the spool out and rewind it neatly. Crossed loops and loose coils are the usual cause.

Troubleshooting and care

If the line keeps jamming, the cause is usually one of three things: the line is wound loosely, the line is the wrong diameter, or the line has gone brittle with age. Rewind with fresh line first. Line stored for a long time in heat or sunlight can dry out and snap, so keep spare line in a cool, shaded spot.

If the line does not come out after you tap or press, pull the ends manually while pressing the release button, if your model has one. If it still will not advance, open the head and check that the line is not stuck under a layer of winding.

After loading, run the trimmer briefly in an open area, clear of people, pets and breakable objects. Keep the guard in place. The guard also helps keep the line at its working length, since a blade on the guard trims it to size on many models.

If you are still shopping and want a head that suits how often you will restring, our cordless string trimmer comparison lists line feed type, cutting swath and line diameter side by side.

Frequently asked questions

How much line should I put on the spool?

Follow the length in your manual. If none is given, fill the spool evenly without letting the line pile above the spool edges, since an overfull spool will not fit in the housing.

Can I use any brand of line in my trimmer?

Usually yes, as long as the diameter matches what your trimmer calls for and the line shape suits the head. Always check the manual, because some heads accept only a narrow range of sizes.

Why does the line keep breaking right at the head?

Rough edges on the eyelets, hitting fences or stone, or old, brittle line can all cause it. Check the eyelets for nicks, trim a bit farther from hard surfaces, and use fresh line.

Do I need to take the battery out every time I add line?

Yes. Removing the battery is the simplest way to prevent an accidental start while your hands are near the head.