Round, square, star-shaped, twisted or with grooves- the range of trimmer lines on the market can be overwhelming. There are three factors that determine which trimmer line is perfect your job: The type of plant to be cut, the engine power of your strimmer or brushcutter and your frequency of use.
Relevant properties
- Thickness of the trimmer line
- Shape
- Wear resistance
- Packaging material
Key criteria
How does the job look like you want the trimmer line to do and what brushcutter you want to use? Look for the following key criteria's:
Type of plants to be cut
- Soft grass
- High grass
- Scrubs
- Engine power
- Reel
- Trimmer head with pre-cut trimmer lines
Thickness trimmer line
Trimmer lines for brushcutters come in a wide variety of shapes: round, hexagonal or even square. The thickness is always given as the trimmer line diameter, even if it is a square line. So, when we talk about the diameter of a square line, we mean the length of the cross-section. The diameter ranges from 1.2 to 4.5mm and is one of the most important characteristics of mowing lines.
It is easy to succumb to the temptation to buy a thread with a larger cross-section because you think you could save working time or that the line would not break so quickly. But the thicker the line, the higher the performance of the brushcutter must be.
A cord that is too thick for a brushcutter with low power can slow down the engine speed. Then there is a risk that the engine will "lock up". A two-stroke engine, for example, only lubricates itself properly when it is running at full speed.
But the opposite is not optimal either: if a too light line is used in a device with a large displacement, it will only give a mediocre result with a high fuel consumption. The following table shows you which diameter your line should have for which displacement of a two-stroke engine:
| Displacement | Diameter trimmer line |
| <20cm³ | 1.2 – 1.4mm |
| 20-25cm³ | 1.6-2.2mm |
| 25-35cm³ | 2.3-2.7mm |
| 35cm³ | 2.7-3mm |
| 40cm³ | 3-3.5mm |
| 40-50cm³ | 3.5-4mm |
| >50cm³ | 3.5-4.5mm |
Diameter trimmer line, type of plants and engine power brushcutter
Small diameter mowing lines (1.2 to 2mm) are designed for cutting small grasses and small plants that are not too tall: Ryegrass, clover ... They should only be used in low-powered implements.
Thicker lines up to 3mm are suitable for taller grasses and are intended for medium power brushcutters. Twisted, toothed or square lines with a line thickness of more than 3mm are used for tall grasses and small bushes. They should only be used in brushcutters with a very high power output.
Diameter of trimmer line and type trimmer head
Only lines of 3mm or less belong in a "standard" head with manual, automatic or semi-automatic unwinding. There is no size limit for heads with pre-cut lines, unless otherwise specified by the manufacturer. In any case, the motor power of your brushcutter is the determining criterion
Trimmer line shapes
To be more precise, this is the shape of the cross-section. Depending on the type of plant you want to cut, the market offers corresponding shapes.
The round line is the standard shape. It can be used in many ways and is often used as standard when you buy your brushcutter.
The square line is known for its robustness. It cuts less regularly because its flat part chops the grass rather than cutting it. However, it is good for rough mowing or lighter clearing work. However, avoid working with it too close to trees or the plaster of your wall!
Star-shaped profile
This line is also called pentagonal or hexagonal because it has 5 or 6 sides respectively. It is a very good cutting tool because of its many sharp edges. The line therefore always has the right cutting position and is just as suitable for tall grass as for work that requires great cutting precision. Another advantage is the even cutting angle, which makes the line extremely wear-resistant.
Nylsaw trimmer lines are only available in large diameters (over 3mm). They may only be used in very powerful devices. They resemble a saw blade and are particularly well suited for scrubby plants. Although a toothed line is sharp like a saw, it is also soft and flexible like conventional nylon. If you use this line in a powerful tool and want to cut plants with hard stems such as thistles, mugwort or blackberries, you do not need a blade.
This is still a recent invention. A twisted line has less air resistance, requires less power from the motor, is quiet and at the same time very robust. This line is very versatile.
| Shape | Advantages | Disadvantages |
| Round | Available in all diameters Suitable for all trimmer heads Robust Easy to reel Content angle | Cuts soft grasses only |
| Square | Available in large diameters Suitable for small bushes Wear- and tear resistant | Not suitable for all trimmer heads Rough cut |
| Star-shaped | Versatile Suitable for small bushes | Not suitable for all trimmer heads
Unclean cut |
| Nylsaw profile | Very efficient for small bushes and hard grasses Can be used instead of a blade | Only suitable for big diameters (>3mm) Only suitable for high power machines |
| Twisted | Silent worker Good results Clean cut Low engine power required Very robust Versatile | Expensive |
No one trimmer line is better than others. Those who regularly use a brushcutter will develop their own preferences depending on the work for which the tool is used. A round and flexible or a twisted trimmer line is more suitable for a lawn, whereas a nylsaw trimmer line is needed for cutting thicker grasses. On each trimmer line you order at Kramp there's a graphic pictogram displayed on the label showing you to which purpose the product is.
Material trimmer lines
The basic material is nylon, a polyamide, which is one of the plastics. High-performance materials are often incorporated to give the trimmer line durability, elasticity, abrasion resistance, etc. For example, fine aluminium particles make a line at the eyelet (hole in the bobbin through which the line exits) more resistant and less likely to break. Depending on how many layers of material it consists of, it is called bi-material, titanium, etc.
Oxo-biodegradable trimmer lines were developed for users who are concerned about protecting our environment and the future of the planet. They have the same technical properties as nylon lines, but decompose within(only) 7 to 10 years.
Spool and pre-cut lines
Mowing lines are available in spools or “ready cut”. Lines offered in spools are intended for trimmer line heads with automatic or manual unwinding.
"Cut lines" are sections of line that are cut to a specific length (for example 26cm, 35cm, 42cm) and inserted into the head by hand. Note that spools with a line to be cut by yourself are cheaper than spools with a pre-cut trimmer line.
Trimmer line for battery machines
Are you looking for a trimmer line for your battery brushcutter? Then the SP66 trimmer line might be the perfect choice for you. This Nylon trimmer line is made of a patent material blend which makes it very stable in use with excellent aerodynamic properties. It is suitable for both professional gardeners and hobbyists which makes this trimmer line a versatile and high-quality product.
Were we able to help you with your decision for your perfect trimmer line or do you still have some questions about this topic? Then please contact our product specialist, find a Kramp dealer near you or contact us at knowledgecenter@kramp.com.
