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Strimmer line keeps breaking: causes and fixes

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In short

Strimmer line usually breaks because it is hitting walls, fences or paving, because it is old and brittle, because it is the wrong diameter for the head, or because it was wound loosely or crossed on the spool. Fit the diameter your manual specifies, wind it tightly and evenly in the marked direction, keep the line tip away from hard surfaces and replace old, dried out line.

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Few garden jobs are more irritating than a strimmer that keeps running out of line. You tap, it feeds, it snaps; you stop to reload, and the job takes twice as long. The cause is almost always one of a handful of things: how you cut, the line itself or how it sits on the spool. This guide works through each in order, with quick checks you can do in a few minutes. Remove the battery before you open the head.

Quick diagnosis

Start with the check that matches what you see, then work down the list below if the problem persists.

SymptomLikely causeFix
Snaps close to the eyeletHitting hard surfaces, or worn eyeletAngle away from walls; check the eyelet for sharp burrs
Snaps inside the headCrossed or loose windingRewind tightly and evenly
Line will not feedLine welded together on the spoolUnwind, cut out fused section, rewind
Brittle, white or cracked lineOld or dried out lineReplace with fresh line
Feeds too much, too oftenHead pressed into ground or bumped too hardHold the head just above the grass
Motor strains, line breaks in thick growthLine too thin or growth too toughUse the specified line; brush cutter for woody growth
Symptom, likely cause, fix

Cutting against walls, fences and paving

This is the most common cause by far. Nylon line wears and snaps on brick, concrete, stone, fence posts and wire. Edging along a path wears line faster than trimming open grass, so some extra use is normal there.

Keep the head angled away from hard surfaces so only the tip of the line touches the grass beside them. Slow down near walls and posts. Fit a guard and keep it on. Finish the last few centimetres beside a wall with hand shears if the line keeps catching. Our guide on how to use a strimmer properly covers technique in more detail.

Old, brittle or wrong line

Nylon line becomes brittle as it ages and dries out, especially if it has spent a few summers in a hot shed. Brittle line snaps on light contact. Store spare line in a sealed bag out of the sun. Some gardeners soak old line in water before use to make it more flexible, but fresh line is the reliable fix.

Line diameter matters. Use the size your manual or the head specifies. For example, the Greenworks 40V G40LT33 in our cordless strimmer guide takes 1.65 mm line. Fitting much thicker line, such as 2 mm or 2.4 mm in a head designed for 1.6 mm, can stop the feed working and overload a small motor. Fitting thinner line than specified makes it break more easily.

  • Check the manual for the line diameter and type.
  • Round line is a good general choice; shaped line cuts tougher grass on heads rated for it.
  • Buy line from a reputable maker and store it sealed and cool.
  • Many makers sell pre wound spools, which avoid winding errors.

Winding the spool correctly

Loose or crossed winding makes line jam, weld together from heat or snap inside the head. Most spools have an arrow showing the winding direction and a divider for dual line heads. The exact method varies by model, so follow your manual.

  1. 1

    Remove the battery and wait for the head to stop.

  2. 2

    Open the head as the manual shows and remove the spool.

  3. 3

    Clean out grass and dirt from the head and spool.

  4. 4

    Cut the length of line the manual gives and hook it into the spool slot.

  5. 5

    Wind tightly and evenly in the direction of the arrow, without crossing turns.

  6. 6

    Leave the specified length free and clip it into the retaining notches.

  7. 7

    Refit the spool, feed the ends through the eyelets and close the head.

Note:Wear eye protection, ear protection and sturdy footwear as listed in your strimmer's manual, plus long trousers. Keep people and pets well clear, and remove the battery before you clear the head, change line or fit a guard.

Worn heads, eyelets and feed problems

Check the metal or plastic eyelets the line exits through. If they are worn sharp, they cut the line from inside. Replacement eyelets or heads are available for many models; ask a dealer or the maker if you are unsure which part fits.

Auto and semi-automatic feed heads, such as those on the Greenworks G40LT33 and Bosch AdvancedGrassCut 36, release line in response to wear or speed. If a head feeds constantly or not at all, it may be dirty, worn or wound wrongly. EGO's Powerload heads reload at the push of a button, according to EGO, but still need the specified line. Consult your manual or a dealer for brand-specific feed issues.

If your strimmer has reached the end of its life, compare current models in our cordless strimmer guide or the mower and strimmer set guide.

Frequently asked questions

Why does my strimmer cord keep breaking? Usually from hitting hard surfaces, old brittle line, the wrong diameter or a poorly wound spool. Work through those in that order.

Can I use 2 mm strimmer line in my strimmer? Only if the manual or head says it accepts 2 mm. Many light cordless trimmers take around 1.6 mm, and thicker line can jam the feed or overload the motor.

Why does strimmer line weld together on the spool? Heat and friction can fuse loosely wound or crossed line. Wind it tightly and evenly, and avoid running the strimmer flat out against walls for long periods.

How long should strimmer line last? It varies with the job. Edging along paving uses far more line than trimming open grass. If you reload every few minutes on open lawn, check the causes above.

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