Best Trimmer Line & Heads

Parts Bin · Parts Catalog · Updated July 2026

String trimmer line is the only cutting tool that is designed to be consumed in use. The nylon or composite line spins at thousands of RPM and cuts grass through velocity rather than sharpness — when it hits something harder than itself, it breaks off and you advance more. Choosing the right line diameter, profile, and material for your trimmer and your cutting conditions eliminates frustrating breakage and dramatically improves cutting performance.

Line Diameter

Trimmer line ranges from .065 inches (light residential) to .155 inches (commercial brush cutting). Thicker line is stronger and cuts heavier vegetation, but requires a more powerful trimmer to spin at effective speed. Using line that is too thick for your trimmer engine bogs the engine and reduces cutting effectiveness. Check your trimmer manual for the recommended diameter range.

Line Profiles

Trimmer Head Types

Bump-feed: The most common type. Tap the head on the ground to advance line through eyelets. Simple and reliable but wastes line if bumped unnecessarily. Works well for residential use.

Automatic-feed: Advances line automatically as it wears. Convenient but can feed too much or too little depending on conditions. Some models are adjustable.

Fixed-line: Pre-cut lengths of line are locked into the head without a spool. Fast to reload in the field — popular with commercial operators who carry pre-cut line. No spool to jam but slightly more waste.

Speed-feed: The spool loads from outside the head without disassembly — thread the line through the head and wind it in place. Dramatically faster than opening the head and hand-winding a spool. The Speed Feed head from Oregon is the category standard.

Shop Trimmer Line & Heads

Line Loading and Spool Management

The most frustrating aspect of bump-feed trimmer heads is reloading the spool. The traditional method requires removing the head cap, pulling out the spool, hand-winding new line in the correct direction (reversing the wind direction is the most common mistake — the line must wrap in the direction that feeds out, not inward), threading the line ends through the eyelets, and reassembling. Getting the wind direction wrong causes the line to bind and not feed when bumped.

Speed-feed heads eliminate most of this frustration. Instead of opening the head, you thread the line through an entry hole in the head body and rotate the head to wind the line automatically. Loading takes 30 seconds instead of 5 minutes, and the wind direction is always correct because the head mechanism controls it. If you spend any significant amount of time trimming and find spool loading annoying, a speed-feed head upgrade is worth every penny.

Pre-cut line systems avoid spooling entirely. Fixed-length pieces of line are inserted into slots in the head and locked in place. When the line wears, you insert new pieces. The advantage is speed in the field — a commercial operator can reload in seconds without stopping the engine. The disadvantage is slightly more line waste because you discard the short remaining pieces rather than using them to the end.

Trimmer Head Compatibility

Replacement trimmer heads must match your trimmer's attachment system. The most common mounting types are bolt-on (a bolt through the center of the head threads onto the drive shaft), bump-knob (the head threads onto the shaft and is retained by a bump knob), and universal adapter (a set of adapters allows one head to fit multiple shaft sizes and thread patterns). Universal heads from Oregon, Shakespeare, and Husqvarna include adapter kits that fit most common trimmer brands, making cross-brand head upgrades straightforward.

Pay attention to the direction of rotation — most trimmers rotate counterclockwise (viewed from below), but some reverse-thread models exist. Installing a head with the wrong thread direction will cause it to unscrew during operation, launching the head and line at high speed. Verify the rotation direction in your trimmer manual before installing any replacement head.

Commercial vs. Residential Line

Commercial-grade trimmer line uses denser nylon compounds and sometimes reinforcement fibers (Kevlar, titanium, or carbon) that resist breakage significantly better than standard residential line. The difference is most noticeable when trimming around fences, posts, rocks, and concrete — situations where the line contacts hard objects frequently. Commercial line costs two to three times more per foot but lasts proportionally longer, making it cost-neutral or even cheaper over a season of use for anyone who trims weekly.

Line storage affects performance. Nylon trimmer line absorbs moisture from the air, which makes it more flexible and resistant to breakage. Line that has dried out (stored in a hot, dry garage for months) becomes brittle and breaks easily. Soak dried-out line in water overnight to restore flexibility. Store bulk line in a sealed container to maintain moisture content. This simple trick dramatically reduces line breakage for seasonal users who store equipment over winter.

Safety and Operating Tips

String trimmers are responsible for a significant number of eye injuries, shin lacerations, and property damage annually. Always wear safety glasses or a face shield when operating a trimmer — the line launches small rocks, debris, and fragments at high velocity in unpredictable directions. Wear long pants and closed-toe shoes to protect against shin strikes from debris and accidental contact with the spinning line. Keep bystanders and pets at least 50 feet away from the cutting area during operation.

Trimmer line can damage tree bark, fence posts, siding, and irrigation heads. Use an edger attachment or reduce throttle when working near these surfaces. Guard against string-girdling young trees — the line cuts through bark quickly and a single pass around a thin trunk can kill the tree by severing the cambium layer. Protective tree guards or mulch rings that keep the trimmer operator at a safe distance from the trunk are inexpensive insurance for landscape trees.

The trimmer guard limits the cutting arc and deflects debris away from the operator. Never remove the guard to increase the cutting swath — this dramatically increases the risk of injury and also allows the line to extend beyond its designed length, which overloads the engine and creates an uncontrolled cutting arc. If you need a wider cutting swath, use a brush cutter with a blade attachment rather than a trimmer with an oversized line length.

Trimmer Attachments Beyond Line

Many string trimmers accept interchangeable attachments beyond the standard line head. Brush cutter blades (steel or plastic) handle heavy brush and saplings that would shred trimmer line instantly. Edger attachments convert the trimmer into a sidewalk and driveway edger. Hedge trimmer attachments reach tall hedges without a ladder. These attachments are typically sold separately and require a drive shaft that supports their weight and load — verify compatibility with your specific trimmer model before purchasing.

For properties with mixed trimming needs — light grass along fences, heavy weeds along ditches, and saplings along fence lines — a trimmer with a brush cutter blade attachment eliminates the need for a separate brush cutter. The key specification is engine power: brush cutter blades require more torque than string line, so engines under 25cc may struggle with heavy blade work. Most trimmers in the 30cc and above range handle blades comfortably.