How-To
Trimmer Line Size: .065 vs .080 vs .095 — What Your Trimmer’s Manual Allows
Which line diameter your string trimmer can take, straight from BLACK+DECKER, RYOBI, CRAFTSMAN and Toro manuals — plus every OEM spool we have mapped, grouped by line size.
Published
The right line size isn’t a matter of taste: trimmer makers state it in the manual, and several warn that heavier line can damage the trimmer. Use the diameter and shape your manual lists.
What four manuals say
| Trimmer (manual) | Line the maker allows | Maker’s warning |
|---|---|---|
| BLACK+DECKER LST400 / LST420 | .065” round (AF-100 spool) | Refill only with .065” round line |
| CRAFTSMAN CMCST900 | 0.065” (1.65 mm) round nylon monofilament | Don’t use serrated or heavier line — it overloads the motor and causes overheating |
| RYOBI RY402013 | 0.065” round or 0.080” twisted | Use original manufacturer’s replacement line for best performance |
| Toro 51831 / 51831T | 2 mm (0.080”) monofilament only | Any other gauge or type could damage the trimmer |
Note that RYOBI allows two sizes on the same head, while CRAFTSMAN and Toro allow exactly one. A thicker line is not an upgrade if your manual doesn’t list it.
OEM spools by line size
These are the pre-wound spools in our spool finder, grouped by the diameter each maker states on its product page or in its manual:
| Line | OEM spools that use it (maker’s own spec) |
|---|---|
| .065" | BLACK+DECKER AF-100, BLACK+DECKER DF-065, BLACK+DECKER RS-136, CRAFTSMAN CMZST065, GREENWORKS 1803702, GREENWORKS 1803802, GREENWORKS 1827802, GREENWORKS 2900719, GREENWORKS 29082, GREENWORKS 29092, GREENWORKS 29242, GREENWORKS 29252, GREENWORKS 2930102, GREENWORKS RA3110382A, GREENWORKS RA3411646A, RYOBI AC14RL3A (twisted), RYOBI AC14RSLA (twisted), TORO 88175, TORO 88518, TORO 88524, WORX WA0004, WORX WA0010, WORX WA0208 |
| .080" | BLACK+DECKER DF-080, BLACK+DECKER SF-080-BKP, CRAFTSMAN CMZST080 (twisted), GREENWORKS 1828102, GREENWORKS 2910602, GREENWORKS 2936602, GREENWORKS 2941802, GREENWORKS 2947302AZ, GREENWORKS 29622, RYOBI AC80RL1 (twisted), RYOBI AC80RL3 (twisted), TORO 88616, WORX WA0014 |
| .095" | EGO AS1300 (twisted) |
Round, twisted or shaped?
Shape matters as much as size. The RYOBI RY402013 manual specifies round line at .065” but twisted line at .080”; CRAFTSMAN’s CMCST900 manual rules out serrated line entirely. WORX uses its own shaped “DoubleHelix” line in several of its spools. Buy the shape your manual names.
Not sure what you have?
Read the size off the old spool or its packaging, or measure the line with calipers — then check it against your manual. Our spool measuring guide walks through it.
Sources: BLACK+DECKER LST400/LST420 instruction manual, p. 10 (PDF); CRAFTSMAN CMCST900 instruction manual (NA473221), p. 8 (PDF); RYOBI RY402013 operator’s manual, pp. 6 and 10 (PDF); Toro 51831/51831T operator’s manual (Form 3440-153 Rev D), p. 16 (PDF); spool line sizes from each maker’s product pages (sources on each spool page). Checked September 25, 2026.
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