Round or square strimmer line for a domestic eyelet
Updated: October 2026
The manual allows more than one profile, and the listings in front of you do not all say which profile they are. Round or square strimmer line is a real choice only after the diameter is already right, and only on the rows that print a shape. Half the table never names one. The [trimmer line comparison](/hub/lawn-and-garden-equipment/trimmer-line) is where those rows sit beside the clashes. This page does not crown a best line. Our links can earn a commission.
The manual allows more than one profile, and the listings in front of you do not all say which profile they are.
The manual allows more than one profile, and the listings in front of you do not all say which profile they are. Round or square strimmer line is a real choice only after the diameter is already right, and only on the rows that print a shape. Half the table never names one. The trimmer line comparison is where those rows sit beside the clashes. This page does not crown a best line. Our links can earn a commission.
Our top picks
| Badge | Product | Stated diameter | Shape | Stated quantity | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Viabrico Viabrico 2.4 mm square | 2.4 mm | Square | 100 m | 7.8 | about £10.99 | View offer |
| Preis-Tipp |  Dapetz Dapetz 1.5 mm x 20 m | 1.5 mm | Round | 20 m | 8.6 | about £2.99 | View offer |
 Oregon Oregon 2.4 mm x 15 m round | 2.4 mm | Round | 15 m | 9.0 | about £5.99 | View offer |
On this page
Round unless the manual offers a choice
Round line feeds through a round eyelet. A square section has edges. ManoMano UK and Kramp’s GB guide both call square line a poor choice next to trees or rendered walls, and both say the stated diameter of square line is one side of the square, not a diagonal.
If the manual or the head names one profile, buy that profile. If the manual names round only, a cheaper square reel is the wrong saving. A grass trimmer’s noise mark sits on the machine, not on the coil. The lawn mower noise rules are about the mower, not the profile.
The round lines in this set
Three bulk rows print a round profile. Dapetz is 1.5 mm by 20 m of round red nylon at £2.99. The title also names other diameters, so confirm this variant. One UK review found the line stiff enough to spring off the spool. Zeqeey is round line at £10.99, titled 1.6 mm by 100 m, with a bullet that also says 1.65 mm, so the profile is settled and the millimetre is not. Oregon part 69-362-OR is round 2.4 mm by 15 m at £5.99, for a head that allows 2.4 mm. Orange is the stated colour, not a code for 2.4 mm. These three are not interchangeable, because 1.5 mm, about 1.6 mm and 2.4 mm are different heads.
The square lines in this set
Two rows print square, and both are Viabrico. One is 2.4 mm by 100 m at £10.99. The other is 2.0 mm at £11.99, with 130 m in the bullet and 425 ft in the title, which agree within ordinary rounding. The conflict is the reviews. Long UK paragraphs appear on both ASINs, including a 380 m reel that is neither specification, so the 4.6 star lines do not compare 2.0 mm square with 2.4 mm square.
Buy it only when the manual allows that profile and that diameter.
What is not a shape choice
Several rows cannot enter this duel. Both SOL packs leave the shape unprinted and share model number 700151SOL. Navoys leaves the shape unprinted and also prints 2.4 mm in the title and 1.65 mm in a bullet. KINGTAIXIN’s Flymo cassette prints neither shape nor diameter. Yeaskyart says “aerodynamic” and does not name round or square.
DRERIO’s bullet does say square spiral, on 25 strands of 37 cm by 3.5 mm at £8.99, for an AFS 23-37 pattern head. It is not a square refill you wind into a domestic bump spool. If the manual names only one profile, buy that profile. If it names none, stay with the round row that matches the diameter you already checked.
Common questions
Is square strimmer line better than round?
It can chop thicker grass more aggressively, if the manual allows that profile and the eyelet can feed it. Round is the usual line for ordinary lawn edges. ManoMano and Kramp both tell you to keep square line off trees and rendered walls. That is their guidance, not a lab score.
Which listings in this set are actually square, and which are round?
Round: Dapetz 1.5 mm by 20 m, Zeqeey’s 100 m reel titled 1.6 mm with 1.65 mm also printed, and Oregon 2.4 mm by 15 m. Square: Viabrico 2.4 mm by 100 m, and Viabrico 2.0 mm at about 130 m or 425 ft. The other listings do not print a profile you can rely on.
Can I put square line in any bump head?
No. The eyelet and the manual have to allow that profile and that diameter. A 2.4 mm square reel in a 1.6 mm round eyelet is a jammed feed, and UK reviews on the Viabrico listings describe thick line that is hard to load and a light strimmer running hot. Check the head before you use a lower price per metre as the reason.
Does the diameter of square line mean the same thing as round line?
You still match the number the head allows. On a square line, ManoMano and Kramp say that number is one side of the square. It is not a cue to buy the next size up because the shape cuts more. A head marked 2.0 mm is still a 2.0 mm head if you choose the square Viabrico reel.
Why are the SOL packs not in this comparison?
Neither SOL listing says round, square or twisted. They also share one model number, so the photos and the stars do not assign a profile to 1.6 mm versus 2.0 mm. Leave them out until the coil in your hand shows a shape the manual allows.
What should I do if the manual names only one profile?
Buy that profile at the diameter the head states. A second shape at a better price per metre is a different product. DRERIO’s square-spiral bullet is a 37 cm by 3.5 mm strand for an AFS 23-37 pattern head, not a square refill for a domestic bump spool. If the manual is silent, stay with the round row that matches the millimetres.
Related pages
Sources
Sources checked for this comparison; last retrieved on 17 October 2026.
- HSE, chain-flail bulletin for brush cutters (retrieved 17 October 2026)
- HSE INDG480, hand-arm vibration (retrieved 17 October 2026)
- GOV.UK, outdoor noise regulations 2001 (retrieved 17 October 2026)
- ISO 11806-1:2022, brushcutters and grass trimmers (retrieved 17 October 2026)
- STIHL GB safety manual for FS machines (retrieved 17 October 2026)
- STIHL UK, AutoCut 2-2 mowing head (retrieved 17 October 2026)
- Yourspares, how to choose strimmer line (retrieved 17 October 2026)
- Consumer Rights Act 2015, section 22 (retrieved 17 October 2026)
- Bosch DIY, extra-strong line 37 cm x 3.5 mm (retrieved 17 October 2026)