Choosing the best STIHL strimmer line for your machine

The best STIHL strimmer line depends on your machine, mowing head and the type of vegetation you are cutting. A lightweight cordless grass trimmer used for lawn edges needs a different line from a petrol brushcutter clearing thick grass, nettles or rough growth.

If you choose line that is too light, it may wear quickly or break too often. If you choose line that is too thick, it may not feed properly, can overload smaller machines and may not fit the mowing head correctly. The easiest starting point is to match your line to the manufacturer’s recommended diameter for your machine and cutting head.

You can browse compatible options in our STIHL strimmer line collection.

What is the best STIHL trimmer line?

There is no single “best” STIHL trimmer line for every job. The best option depends on whether you are trimming lawn edges, cutting longer grass, clearing weeds or working through tougher vegetation.

• Round mowing line: a good general-purpose option for grass trimming and everyday garden maintenance.
• Square mowing line: designed to give a more aggressive cutting edge, useful where you need more bite through heavier grass.
• Pentagonal mowing line: shaped to improve cutting performance and efficiency in tougher conditions.
• CF3 Pro-style high-tech line: a premium option for users who want stronger performance and longer life from their mowing line.

For regular domestic edging, a standard round line is often enough. For professional users, contractors and demanding garden work, shaped or reinforced STIHL mowing line can be a better choice.

Shop STIHL strimmer line online to compare the available options.

What size line does my STIHL trimmer use?

The correct line size depends on the exact STIHL trimmer model and mowing head fitted. Common STIHL mowing line diameters include sizes such as 1.6 mm, 2.0 mm, 2.4 mm, 2.7 mm, 3.0 mm and heavier professional options, but not every machine can run every size.

As a simple guide:

• 1.6 mm – 2.0 mm: lighter trimming, edging and smaller cordless/electric machines.
• 2.4 mm: common for general grass trimming and mid-range machines.
• 2.7 mm – 3.0 mm: heavier vegetation, professional brushcutters and tougher grass.
• 3.3 mm+: specialist heavy-duty clearing, only where the mowing head and machine allow it.

Always check your machine manual, mowing head markings or existing line size before ordering. Using the wrong line diameter can cause poor feeding, line welding, reduced cutting performance or unnecessary strain on the machine.

How to replace the line in a STIHL strimmer

Replacing STIHL strimmer line depends on the mowing head fitted to your machine. Some heads need to be opened so the line can be wound onto the spool, while Comfort-style heads allow the line to be inserted and wound from the outside by rotating the head. Pre-wound replacement spools may also be available for some models.

STIHL recommends soaking mowing line in water for 24 hours before winding it onto the mowing head. This helps the line retain moisture and elasticity, which can reduce brittleness and snapping.

What is the strongest strimmer line?

The strongest strimmer line is usually a combination of the right material, the right shape and the right diameter for the machine. Thicker or reinforced line can last longer in demanding conditions, but only if the trimmer and mowing head are designed to run it.

For tougher work, shaped mowing lines such as square, pentagonal or high-tech reinforced lines are often better than basic round line because they provide a more aggressive cutting profile and improved durability. For very dense vegetation, STIHL cutting heads such as DuroCut can use thicker serrated line pieces on suitable machines.

The key is not simply to choose the thickest line available. The strongest usable line is the one that your machine can feed properly while still maintaining good cutting speed.

Does thicker trimmer line last longer?

Thicker trimmer line can last longer because there is more material to wear down during cutting. It can also be more resistant to snapping when working around walls, fences, paving and tougher stems.

However, thicker is not always better. If the line is too large for your machine, it may reduce head speed, feed poorly or put extra load on the motor or engine. Smaller machines often perform better with a thinner line that spins quickly and feeds cleanly.

For most users, the best approach is to choose the thickest line recommended for your specific STIHL model and mowing head — not the thickest line available overall.

Common problems with STIHL strimmers and strimmer line

Many STIHL strimmer problems are linked to line size, line condition, spool loading or mowing head wear. Here are the most common issues and what to check.

Line keeps snapping

This can happen when line becomes dry and brittle, when it is the wrong diameter, or when you are cutting against hard surfaces too aggressively. Soaking line before use can help improve flexibility.

Line will not feed

Check that the line is not crossed inside the spool, the head is not overfilled and the line diameter is compatible with the mowing head.

Line welds together inside the head

Line welding is often caused by heat build-up from heavy cutting, overloading the head or using line that is too thin or poor quality for the job.

Strimmer feels weak or slow

If the line is too thick, the machine may struggle to keep head speed. Try returning to the recommended line size.

Uneven cutting performance

Make sure both line ends are the same length and that the line has been loaded correctly. A damaged mowing head or worn spool can also affect performance.