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Strimmer line buying guide: the head decides first

Updated: October 2026

You already own the strimmer, and the next purchase is a coil, a cassette or a packet of strands from amazon.co.uk. Shelf prices here run from £2.99 to £12.99. A strimmer line buying guide that starts with stars or with metres will hand you a 2.4 mm reel for a 1.6 mm eyelet, or a £2.99 Flymo cassette whose diameter is never printed. The [trimmer line comparison](/hub/lawn-and-garden-equipment/trimmer-line) is the twelve-row table, including the listings that disagree with themselves. This page is the order of the checks: line to wind, a cassette that snaps in, or a 37 cm strand. Our links can earn a commission.

You already own the strimmer, and the next purchase is a coil, a cassette or a packet of strands from amazon.co.uk. Shelf prices here run from £2.99 to £12.99.

Our top picks

DRERIO DRERIO 3.5 mm x 25

Best overall

DRERIO DRERIO 3.5 mm x 25
6.2/10about £8.99
View offer
Dapetz Dapetz 1.5 mm x 20 m

Preis-Tipp

Dapetz Dapetz 1.5 mm x 20 m
8.6/10about £2.99
View offer
Oregon Oregon 2.4 mm x 15 m round

Rank 3

Oregon Oregon 2.4 mm x 15 m round
9.0/10about £5.99
View offer
On this page
  1. 1.The head decides, the grass does not
  2. 2.Reel, cassette, or 37 cm strand
  3. 3.Four listings that do not agree with themselves
  4. 4.If your garden looks like this

The head decides, the grass does not

The first number is the one on the head, the spool or in the manual, not the length of the grass. A size chart is a rule of thumb for the day the head allows a range. Yourspares puts the recommended diameter first and warns that line which is too thick strains the machine and mis-feeds, while line which is too thin snaps. STIHL UK’s AutoCut 2-2 page names 1.6 mm and 2.0 mm for particular machines: the head owns the millimetres. A small lawn with a petrol head marked 2.4 mm is not a 1.2 mm job because the garden looks modest. If the head and a chart disagree, buy the head’s number.

Reel, cassette, or 37 cm strand

This set has three formats, and they are not interchangeable once the diameter is known. Bulk line, such as the Oregon donut or the Zeqeey holder, is wound onto the spool already in the machine. A pre-wound cassette, such as the KINGTAIXIN Flymo spool or the Yeaskyart four-pack, snaps in. Pre-cut strands, the DRERIO and Eyoloty packs at 37 cm by 3.5 mm, go into a Bosch AFS 23-37 pattern head and will not wind into a domestic bump spool. A 100 m reel looks cheaper per metre until the head only accepts a named cassette. “Universal” on a bullet is not a fit.
DRERIO DRERIO 3.5 mm x 25

Testsieger

DRERIO DRERIO 3.5 mm x 25
6.2/10about £8.99
View offer

Four listings that do not agree with themselves

Four rows are unfinished as descriptions, and price does not repair that. Navoys at £3.75 titles the coil as 2.4 mm by 15 m and a bullet calls it 1.65 mm, so you cannot tell which diameter will arrive. Zeqeey at £10.99 titles 100 m as 1.6 mm and a bullet says 1.65 mm. Yeaskyart prints 11 inches in the title and 11 ft in the bullet. KINGTAIXIN at £2.99 names Flymo Contour XT, Mini Trim and Revolution, and never prints a diameter. Under the Consumer Rights Act 2015, section 22, goods should match the description, and two sizes are not one description. If a page cannot state one size, leave it.

If your garden looks like this

If the head is marked 1.6 mm and you wind your own line, a 2.4 mm reel is the wrong economy. Confirm one printed diameter, then choose round or square only if the manual allows it. If the head is marked 2.4 mm and takes round line, the Oregon 69-362-OR donut at £5.99 is the traceable short coil here, though 15 m is a small refill if the line snaps. If you own a Bosch AFS 23-37, you are buying 37 cm strands at 3.5 mm, not a bulk reel. That exception is on the diameter page. Keep the guard on, stop the motor before you open the head, and stay with nylon. Do not fit linked metal flails.

Common questions

What should I check before I look at the price?
Check the diameter the head or the manual allows, then the format: a reel you wind, a cassette that snaps in, or a pre-cut strand. Price and star ratings come after those two, because a cheap coil in the wrong millimetre will not feed.
Is a 100 m reel better value than a 15 m donut?
It is cheaper per metre only after the diameter matches. Zeqeey’s 100 m at £10.99 is more line than Oregon’s 15 m at £5.99, and it is still the wrong buy for a head marked 2.4 mm.
Why is “universal” not a fit?
Universal, on these listings, means the seller hopes the diameter matches. It does not name your head. Yeaskyart’s bullets say all trimmers while the title names particular Ryobi voltages and AC14RL3A. A 2.4 mm line still has to match a head that accepts 2.4 mm, whatever the brand list underneath.
What is different about a pre-wound cassette and a pre-cut strand?
A cassette is a plastic shell with line already wound, and you swap the whole shell. A pre-cut strand in this set is a 37 cm length for an AFS 23-37 pattern head, and you insert it rather than wind it. Neither format is a loose coil you load into a bump spool at the weekend.
Which listings in this set contradict themselves?
Navoys prints 2.4 mm and 1.65 mm. Zeqeey prints 1.6 mm and 1.65 mm. Yeaskyart prints 11 inches and 11 feet. KINGTAIXIN prints no diameter. The two SOL packs also share one model number, and the two Viabrico listings share review text, which is a different problem: the stars are not separate tests.
Do star ratings on the SOL packs compare 1.6 mm with 2.0 mm?
No. Both extracts print model 700151SOL, and the review samples overlap, including wording that does not match the blue colour field on the 1.6 mm listing. Read the stars as a shared pool, not as a verdict on which diameter lasts longer.

Related pages

How to wind trimmer line

Round or square trimmer line

Trimmer line

Best strimmer line for the diameter you already know

What size strimmer line do I need for this machine

Sources

Sources checked for this comparison; last retrieved on 17 October 2026.

  1. HSE, chain-flail bulletin for brush cutters (retrieved 17 October 2026)
  2. HSE INDG480, hand-arm vibration (retrieved 17 October 2026)
  3. GOV.UK, outdoor noise regulations 2001 (retrieved 17 October 2026)
  4. ISO 11806-1:2022, brushcutters and grass trimmers (retrieved 17 October 2026)
  5. STIHL GB safety manual for FS machines (retrieved 17 October 2026)
  6. STIHL UK, AutoCut 2-2 mowing head (retrieved 17 October 2026)
  7. Yourspares, how to choose strimmer line (retrieved 17 October 2026)
  8. Consumer Rights Act 2015, section 22 (retrieved 17 October 2026)
  9. Bosch DIY, extra-strong line 37 cm x 3.5 mm (retrieved 17 October 2026)