Trimmers & Edgers
Trimmer heads explained
Reloading line is the worst job in yard work. The head on the trimmer decides how often you do it and how badly it goes.
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We have not tested these units. Every spec on this page comes from the manufacturer's own documentation and is linked to it. Every computed figure is arithmetic you can redo. Prices are checked daily — last verified January 1, 1970. Here is exactly how we pick.
Trimmer heads get about one line of the spec sheet and cause about half the ownership experience. There are three designs on the market, manufacturers publish very little about any of them, and the difference between them shows up on the day you run out of line rather than the day you buy.
The short answer
The three designs
Bump feed
A spool of line inside the head, released a few inches at a time when you tap the head on the ground with the motor running. A blade on the guard trims the excess to the right length automatically.
It is the standard because it works: you never stop to reload mid-job, and the line advance is under your control. Greenworks publishes a spiral twist dual-line bump feed on the ST80L210; Ryobi publishes a 0.095 in bump feed on the RY402110. The cost is the reload itself — opening the head and winding a spool by hand, in the right direction, with both ends threaded.
Automatic winding
The head winds the spool for you. On EGO's POWERLOAD system you thread a straight length of line through the head and press a button; the motor does the winding.
This is the feature worth paying for if you dislike the reload — and most people do. It does not change how the trimmer cuts, and it does not change how fast line wears. It changes one five-minute job that happens a few times a season into a ten-second one.
Fixed line
Short pre-cut lengths clipped into a head, replaced individually when they wear. No spool, no winding, nothing to tangle — and no reserve, so you carry spares and stop more often. None of the trimmers in our registry ships with one; they are usually an aftermarket head.
What the three trimmers publish about their heads
| Spec | EGO ST1521S | Ryobi RY402110 | Greenworks ST80L210 |
|---|---|---|---|
| Head type | POWERLOAD automatic winding | Bump feed | Spiral twist dual-line bump feed |
| Line gauge | 0.095 in dual-feed | 0.095 in | 0.080 in |
| Cutting swath | 15 in | 15-17 in adjustable | 16 in |
| Motor speed | Not published | Not published | 6200 RPM |
| Shaft | Carbon fiber, split shaft | Carbon fiber | Not published |
| Weight | Not published | 8.8 lb bare / 12.9 lb with 6.0Ah | 7.1 lb without battery |
| Runtime claim | Up to 30 min on 2.5Ah | Up to 67 min | Up to 45 min |
| Spool capacity | Not published | Not published | Not published |
| Warranty | 5-yr tool / 3-yr battery, lifetime shaft | Not published on the page | 3-yr tool / 4-yr battery |
Transcribed from the EGO ST1521S, Ryobi RY402110 and Greenworks ST80L210 product pages.
Line gauge is the other half of the head
A head is rated for a line diameter, and fitting heavier line than the rating is how heads get destroyed. The published gauges here are 0.080 in (Greenworks) and 0.095 in (EGO, Ryobi).
Full detail on gauges, shapes and when the heavier line is worth its runtime cost is in trimmer line guide.
Reloading a bump head without losing an afternoon
- Take the battery out. Every head job starts there.
- Note the winding arrow before you unwind anything. Winding backwards is the single most common mistake, and the head will jam on the first tap.
- Wind under tension, in tidy layers. Loose coils cross over each other and weld together under heat.
- Leave both ends in the retaining notches until the spool is back in the housing, then thread them through the eyelets.
- Store spare line in the dark. UV and heat make line brittle, and brittle line breaks at the eyelet every few minutes.
Cleaning, storage and blade-guard care are in trimmer maintenance.
What we cannot tell you
We have not stripped these heads down. None of the three manufacturers publishes a spool capacity in feet, a line advance per bump, a head service life, or a replacement head part number on the product page. EGO publishes no motor speed; Ryobi publishes no warranty term. What is published is the head type and the line gauge, and those two facts carry most of the buying decision.
The products discussed
Specs are the manufacturer's own and linked to the page they came from. Prices come from a live daily check; where we have no verified price we say so rather than print a stale one.
EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S
EGO · EGO 56V ARC Lithium · Our score 8.9/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
A lifetime shaft warranty and a head that reloads line at the push of a button -- the two things that actually go wrong with a string trimmer.
Published specs
| Cutting swath | 15 in |
|---|---|
| Line | 0.095 in dual-feed spiral twist |
| Head | POWERLOAD automatic winding |
| Shaft | Carbon fiber, split shaft |
| Battery (kit) | 56V 2.5Ah |
| Runtime claim | Up to 30 min on 2.5Ah |
| Charge time | 50 min |
| Warranty | 5-yr tool / 3-yr battery, lifetime shaft |
Source: POWER+ 15" POWERLOAD String Trimmer with Carbon Fiber Shaft, egopowerplus.com
56V x 2.5Ah = 140Wh. 30 minutes of published runtime from 140Wh is about 4.7Wh per minute -- roughly a quarter of what a blower on turbo burns.
What the numbers favor
- Lifetime warranty on the carbon fiber shaft, published
- POWERLOAD winds the line for you -- the job everyone hates
- 0.095 in line, the heavier of the two common home gauges
- Split shaft, so it takes EGO's multi-head attachments
What they don't
- Ships with the small 2.5Ah pack; 30 minutes is a modest published runtime
- EGO does not publish a weight for this configuration
you only edge a short driveway. An 8 in edger attachment on a power head you already own does that job better and costs a fraction.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Ryobi 40V HP Whisper 17" Carbon Fiber RY402110
Ryobi · Ryobi 40V · Our score 8.6/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
67 published minutes and a swath you can dial from 15 to 17 inches -- the only adjustable-swath trimmer here.
Published specs
| Cutting swath | Adjustable 15-17 in |
|---|---|
| Line | 0.095 in bump feed |
| Shaft | Carbon fiber |
| Battery (kit) | 40V 6.0Ah |
| Runtime claim | Up to 67 min |
| Weight | 8.8 lb bare / 12.9 lb with 6.0Ah |
| Length | 72.25 in |
Source: 40V HP Brushless 17" String Trimmer (RY402110), ryobitools.com
40V x 6.0Ah = 240Wh. 67 minutes from 240Wh is about 3.6Wh per minute -- the most efficient published figure of the three trimmers here.
What the numbers favor
- 67 minutes published, more than double the EGO kit's 30
- Swath adjusts 15-17 in, so tight borders and open verge get the same tool
- Best published watt-hours per minute of the trimmers on this page
- Whisper Series noise engineering, same line as the 57 dB blower
What they don't
- 12.9 lb with the 6.0Ah pack fitted -- the heaviest trimmer here, and it is held at arm's length
- Ryobi publishes no noise figure for this specific model
- Bump feed, not an automatic reload head
you have wrist or shoulder trouble. 12.9 lb on the end of a 72 in shaft is a lot of leverage, whatever the runtime says.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Greenworks 80V 16" String Trimmer ST80L210
Greenworks · Greenworks 80V · Our score 8.4/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
7.1 lb bare with a 30-minute recharge and a 4-year battery warranty -- the lightest way onto the 80V platform.
Published specs
| Cutting swath | 16 in |
|---|---|
| Motor | Brushless, 6200 RPM |
| Line | 0.080 in spiral twist dual-line bump feed |
| Battery (kit) | 80V 2.0Ah |
| Runtime claim | Up to 45 min |
| Recharge | 30 min |
| Weight | 7.1 lb without battery |
| Warranty | 3-yr tool / 4-yr battery |
Source: 80V Cordless 16" Brushless String Trimmer (ST80L210), greenworkstools.com
80V x 2.0Ah = 160Wh. 45 minutes from 160Wh is about 3.6Wh per minute, matching the Ryobi almost exactly despite half the pack size.
What the numbers favor
- 7.1 lb bare, the lightest published trimmer weight here
- 30-minute recharge, the fastest on this page
- 4-year battery warranty
- Publishes motor RPM, which neither EGO nor Ryobi does for their trimmers
What they don't
- 0.080 in line is the lightest gauge here -- it will break more often in heavy weeds
- 160Wh included is a small pack for an 80V platform
- Bump feed, not automatic reload
you cut heavy brush or thick weed stems. 0.080 in line is a lawn-edge gauge, not a bramble gauge.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Where to buy the tools on this page
Every link below is an Amazon affiliate link. We show no price we have not verified today, so where there is no live figure the link says "check price" and takes you to the listing to read it there.
Best overall
EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S
EGO · EGO 56V ARC Lithium
Best runtime
Ryobi 40V HP Whisper 17" Carbon Fiber RY402110
Ryobi · Ryobi 40V
Best light 80V option
Greenworks 80V 16" String Trimmer ST80L210
Greenworks · Greenworks 80V
#ad As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. How we're funded.
Common questions
What is the best type of trimmer head?
What is a bump feed trimmer head?
How do you load a trimmer head?
What line gauge should I use?
Why does my trimmer line keep breaking?
Sources
Read next
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- Cordless string trimmer maintenance
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- String trimmer buying guide: the four specs that matter
Line gauge, head type, shaft and loaded weight -- the four specs that decide how a trimmer feels.
- Best string trimmer and edger combo
Attachment systems that trim and edge on one motor, with the published depths each one reaches.