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Quick answer
Round line is the everyday choice; shaped line is for heavier growth. Oregon calls round the most common line, ideal for everyday residential use, and says it lasts longer than edged lines. Square line's four sharp edges slice through thicker grass and dense weeds. Twisted line grabs thicker, overgrown vegetation and reduces engine drag and vibration.
Trimmer line (Oregon Gatorline range):
Oregon Gatorline round, square and twistThe shapes compared
| Shape | Best for | Source |
|---|---|---|
| Round | Everyday yards, grass with few weeds. Lasts longer than edged line. | Oregon |
| Square | Thicker grass and dense weeds, medium to large jobs. STIHL calls it more aggressive for thick, woody grass. | Oregon, STIHL |
| Twist | Thicker, overgrown growth, with less engine drag and vibration. | Oregon |
| Quiet / spiral | Less wind noise. STIHL suggests it for battery and electric trimmers. | STIHL |
Which to buy
- Mostly lawn edges: round, in the diameter your head is approved for.
- Weedy fence lines and thick grass: square or twist.
- Quieter battery trimmer: a quiet or spiral line, if your head accepts it.
Oregon also sells its Gatorline in three tiers: regular for low to medium grass, Magnum for heavier vegetation and dense weeds, and Platinum for thick, rough growth around rocks and fences.
Shape doesn't change the size rule. Whatever the shape, use a diameter your head is approved for. See the size chart.
How we work: shape uses come from Oregon's FAQ and STIHL's guides. We don't test trimmer line ourselves. Sources are listed below.
Questions people ask
Is round or square trimmer line better?
Oregon says round is the most common, for everyday residential use, and lasts longer. Square has four edges for thicker grass and dense weeds.
What does twisted trimmer line do?
Oregon says the twist helps grab thicker, overgrown vegetation and reduces engine drag and vibration.
Is there a quieter trimmer line?
STIHL makes a Quiet Line with spiral grooves for less wind noise, suggested for battery and electric trimmers.
Sources
Last checked Oct 23, 2026. Sizes come from STIHL; shapes from Oregon and STIHL; breakage causes from Echo, Husqvarna and Ryobi. Stop the engine or remove the battery before opening the head.
