Learning how to restring a string trimmer is one of the most useful skills for keeping your lawn edges crisp without paying for repairs or buying a new tool. When the line snaps, wears down, or welds itself inside the spool, the trimmer stops cutting – but replacing the line takes only a few minutes once you know the steps. This guide walks you through restringing both bump-feed and fixed-line trimmer heads, choosing the right line, and fixing the problems that make line jam or break.
Quick answer: To restring a string trimmer, remove the battery or unplug it, take off the spool cap, wind 10 to 20 feet of fresh trimmer line onto the spool in the direction of the arrow, feed the ends through the eyelets, and snap the cap back on. Most electric and gas trimmers use the same basic bump-feed spool, so the process is nearly identical across brands.
Key takeaways
- Always cut the power first – remove the battery, disconnect the plug, or pull the spark plug wire before touching the head.
- Match the line diameter to your trimmer: 0.065 inch for light electric models, 0.080 to 0.095 inch for gas trimmers.
- Wind the line tightly and evenly in the direction of the arrow on the spool, leaving 5 to 6 inches loose at each eyelet.
- Do not overfill the spool; line should sit below the rim so the cap seats fully.
- A pre-wound replacement spool is the fastest fix if you would rather skip winding.
Why does a string trimmer need restringing?
A string trimmer cuts grass with a spinning nylon line that wears down every time it hits pavement, fences, or thick weeds. Because the line is a consumable part, it eventually gets too short to reach the grass, snaps off at the eyelet, or fuses together inside the spool from friction heat. Restringing simply means replacing that worn nylon with fresh line so the head can feed cutting length again. Knowing how to restring a string trimmer means you can solve this in minutes instead of visiting a repair shop. Most homeowners restring several times per season, and doing it yourself saves the cost and wait of a repair shop.
What line and tools do you need?
Before you start, pick the correct trimmer line. Using line that is too thick can overload a small motor, while line that is too thin breaks quickly on heavy growth. Check your operator manual for the recommended diameter, then match the shape to the job.
| Line diameter | Best for | Typical trimmer |
|---|---|---|
| 0.065 – 0.070 in | Light grass, edging | Small corded and battery models |
| 0.080 – 0.085 in | Average lawns, light weeds | Mid-size battery and small gas |
| 0.095 – 0.105 in | Thick weeds, tall grass | Gas and high-power battery |
Round line is the cheapest and most durable choice for general trimming. Twisted or square line cuts faster and cleaner on dense weeds but wears a little quicker. You will also want work gloves, safety glasses, and scissors or a sharp knife to cut the line. That is all the equipment most jobs require.
How do you restring a bump-feed string trimmer?
The bump-feed head is the most common design, where tapping the head on the ground releases more line. Follow these steps to wind fresh line onto the spool.
- Cut the power. Remove the battery, unplug the cord, or disconnect the spark plug wire so the trimmer cannot start accidentally.
- Open the head. Press the tabs on the sides of the cap, or twist it counterclockwise, then lift off the cap and pull out the old spool.
- Clear out debris. Remove any broken line pieces and brush grass clippings out of the housing so the new spool seats cleanly.
- Cut the new line. Measure 10 to 20 feet of line, following the length listed in your manual, and cut it with scissors.
- Anchor the line. Insert one end into the notch or hole in the center of the spool so it holds while you wind.
- Wind in the arrow direction. Wrap the line tightly and evenly onto the spool in the direction marked by the arrow. Keep the coils flat so they do not tangle.
- Secure the ends. Leave 5 to 6 inches loose and hook them into the retaining slots on the spool rim.
- Reinstall the spool. Feed the loose ends through the eyelets in the housing, drop the spool back in, and press the cap on until it clicks.
- Test the feed. Reconnect power, run the trimmer briefly, and bump the head to confirm the line advances.
How much line should you wind on?
Wind between 10 and 20 feet depending on the spool size, and stop when the line sits about a quarter inch below the outer rim. Overfilling is the single most common mistake: a packed spool prevents the cap from seating and stops the line from feeding. When in doubt, wind less rather than more.
How do you restring a fixed-line or speed-feed head?
Fixed-line heads and speed-feed heads skip the spool entirely, which makes them faster to reload. For a fixed-line head, cut two short pre-measured pieces of line and push each one through the holes until the ends are even. For a speed-feed head, line up the arrows on the head, thread a single length of line straight through until both sides are equal, then turn the knob to wind it in automatically. These designs let you reload in under a minute without opening the housing.
How do you load a pre-wound replacement spool?
If you would rather not wind line by hand, buy a pre-wound spool made for your trimmer model. Cut the power, remove the cap and old spool, then drop the new pre-wound spool into the housing. Feed the loose line ends through the eyelets, pull them so a few inches stick out, and replace the cap. Pre-wound spools cost a little more per foot but are the quickest option when you are short on time.
How do you operate a freshly strung trimmer safely?
Once the line is loaded, put on eye protection before you start. Nylon line spins fast enough to throw grit and debris toward your face, so safety glasses or a face shield are essential. Federal workplace safety rules under the OSHA eye and face protection standard require protective eyewear whenever there is a hazard from flying particles, and the same logic applies at home. Wear long pants, closed shoes, and gloves, keep bystanders at least 30 feet away, and hold the head parallel to the ground for an even cut.
Common string trimmer line problems and fixes
Even a freshly strung trimmer can act up. Here are the most frequent issues and how to solve them.
- Line will not feed: The line is wound too tightly or overfilled. Rewind with fewer, flatter coils below the rim.
- Line keeps breaking: You may be hitting hard surfaces or using line that is too thin. Step up one diameter and avoid concrete.
- Line is welded together: Heat from rapid use fused the coils. Pull the stuck sections apart, and store spare line out of direct sun.
- Line feeds too much: A worn cap or spring lets the head release extra line. Replace the cap or spring assembly.
- Uneven cutting: The two line ends are different lengths. Trim them even so the head stays balanced.
Ready for a trimmer that holds more line and feeds smoothly?
If your current trimmer eats through line or is a chore to reload, an upgrade with a larger spool and reliable feed system can save real time. See our tested picks in the roundups of the best battery powered string trimmers and the best gas powered string trimmers, or compare cordless value in our guide to the best battery weed trimmers. Each guide notes line capacity and how easy each model is to restring.
Frequently asked questions
How often should I restring a string trimmer?
Most homeowners restring every few uses during peak season, or whenever the line is too short to reach the grass. Heavy weed cutting and frequent contact with hard surfaces wear line faster, so a spool may last a single large yard or several small trims.
Can I use any brand of trimmer line?
Yes, as long as the diameter matches your trimmer. Line is largely universal by size, so a 0.080 inch line from one brand fits any head rated for 0.080 inch. Always follow the diameter listed in your operator manual to protect the motor.
Which way do I wind the trimmer line?
Wind in the direction of the arrow printed on the spool. Winding the wrong way stops the line from feeding because the head spins opposite to the coil. If there is no arrow, wind against the direction the head rotates during use.
Why does my trimmer line keep jamming?
Jamming usually comes from overfilling the spool or winding the coils loosely so they cross over each other. Rewind the line tightly and evenly, keep it below the rim, and make sure the cap seats fully so the feed mechanism works.
Is thicker trimmer line always better?
No. Thicker line cuts heavier growth but strains small motors and can overheat a light electric trimmer. Match the line to your machine rather than defaulting to the thickest option, and only step up a size when you regularly cut thick weeds.
Final thoughts
Now that you know how to restring a string trimmer, this five-minute job keeps your equipment cutting all season and saves the cost of professional service. Cut the power, choose the right line diameter, wind evenly in the arrow direction, and you are ready to trim. After edging, a quick pass with a blower makes cleanup easy – see our guide on how to use a leaf blower effectively to finish the yard fast.