Best string trimmer for fence lines

Every other trimming job is grass against line. A fence line is line against steel, wood or masonry, and the line always loses. This is the one use case where consumable cost and reload speed matter more than runtime or swath.

The short answer

Gauge is the first decision

Line diameter decides how many impacts a length survives before it wears back into the head. Against grass the difference is marginal. Against chain link it is the whole job.

Adjustable swath is the underrated one

The line tip travels fastest and does the cutting, and it is also the part that contacts the fence. Narrowing the cutting width pulls the tip back from the wire while you still cut the grass in front of it.

Two trimmers in our registry publish an adjustable width: RYOBI at 15 to 17 inches and Greenworks at 14 to 16. The other two are fixed, which means the only control you have along a fence is your own arm.

1. RYOBI RY402110 — heavy gauge and an adjustable path

Nought point nine five inch line, a 15 to 17 inch adjustable swath and up to 67 published minutes on the 240Wh in its kit. For a long fence line that is the right combination: the heavier line to survive the wire, the narrower setting to avoid it, and enough battery to finish the run.

Against it: bump feed means you reload by hand when the spool empties, and a fence line empties spools. At 12.9 lb with the 6.0Ah pack fitted it is the heaviest loaded trimmer we hold specs for, and RYOBI publishes no warranty on this product page.

#ad Check the Ryobi 40V HP Whisper 17" Carbon Fiber RY402110 price on Amazon — how we're funded.

2. EGO ST1521S — the reload problem, solved

Same 0.095 inch gauge, and POWERLOAD winds the line for you. On the job that empties spools fastest, the head that makes refilling painless has a strong claim — and the lifetime carbon fiber shaft warranty is worth noting on a tool that gets levered against posts.

Against it: a fixed 15 inch swath with no way to narrow it, and 30 published minutes on the 140Wh kit pack. Buy it on a platform where you already own a larger battery.

#ad Check the EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S price on Amazon — how we're funded.

3. Greenworks 2123802 — both gauges, and a narrower minimum

Published for both 0.080 and 0.095 inch line, with a 14 to 16 inch adjustable path — the narrowest minimum setting in our registry, which is exactly what you want against a post. Fifty published minutes on 200Wh, and a four-year warranty on both tool and battery.

Against it: at 9.15 lb bare it is the heaviest unloaded trimmer here, and Greenworks publishes no shaft material.

#ad Check the Greenworks 80V 16" Attachment-Capable String Trimmer (2123802) price on Amazon — how we're funded.

Different fences, different damage

"Fence line" covers several quite different problems, and the right approach is not the same for each.

Why the tip does the damage

Greenworks publishes a 6200 RPM motor speed on the ST80L210; no other trimmer in our registry publishes one, so the absolute tip speeds cannot be compared across brands. The relative effect of narrowing the swath holds regardless of the motor.

Bump feed or automatic, on a job that empties spools

Head type matters more here than on any other trimming job, because this is the job that runs you out of line.

• Bump feed advances line by tapping the head on the ground while it spins. It is simple and reliable, and reloading means opening the head and winding a spool by hand — three of the four trimmers here work this way.
• Automatic winding (EGO POWERLOAD) feeds the line through and winds it for you. On a fence line, where you may reload more than once in a session, that is the difference between finishing and giving up.
• Dual-line heads cut with two strands, which shares the wear but doubles the consumption rate. Both Greenworks trimmers publish dual-line heads.

What each head design does mechanically is covered in trimmer heads explained.

The permanent fix, costed in effort rather than money

Everything above manages a problem that can be removed. A mowing strip — a band of paver, brick or gravel running under the fence line — means the mower deck reaches the fence and the trimmer never has to.

1. Gravel band: cheapest, fastest to install, needs topping up and will grow weeds eventually.
2. Paver or brick strip: more work, more durable, and it gives the mower a wheel surface so the deck can overhang the edge.
3. Neither, on a long rural fence. At some length the strip stops being worth it and the honest answer is heavy line and a wide swath.

It costs one weekend and it removes a recurring job for as long as you own the house. That is a better return than any trimmer on this page.

Four ways to spend less line

1. Narrow the swath if the tool lets you. Free, immediate, and the single biggest reduction available.
2. Cut with the tip, not the side of the head, and approach the fence rather than sweeping along it.
3. Work the grass out from the fence first, then trim the last inch, so most of the pass never touches wire.
4. Fix it permanently if you can. A mowing strip or a gravel band under the fence removes the job. It costs once; line costs every season.

What each head type does, and why bump feed and automatic winding behave differently, is in trimmer heads explained.

The buying checklist, in order

1. Does it take 0.095 in line? Three of the four trimmers here do. The heavier gauge carries 41% more cross-sectional material to wear away.
2. Can the swath be narrowed? Two of the four publish an adjustable width. It is the one free control you get over consumption.
3. How painful is reloading? On the job that empties spools, an automatic head is worth real money.
4. Is there enough battery to finish the run? A long fence is a large-yard problem — see trimmers for large yards.
5. Is the shaft warranted? The shaft is what gets levered against posts, and only one trimmer in our registry publishes a lifetime term on it.

What we cannot tell you

We have not trimmed a fence with any of these. No maker publishes a line wear rate, a consumption figure per hour, or how much line a spool holds, so the gauge arithmetic above describes cross-sectional area rather than measured durability. Nobody publishes a shaft material for the two Greenworks trimmers, and RYOBI publishes no warranty on the page we cite.