The EGO POWER+ 56V 15-Inch POWERLOAD ST1521S is the best cordless string trimmer for most people. It cuts a full 15-in. swath, reloads line with the push of a button, and its carbon-fiber split shaft keeps the tool light and well balanced for long sessions around fences, beds, and sidewalks. Already invested in another battery platform? The DEWALT DCST925M1 is the natural pick for DEWALT 20V MAX owners, while the Milwaukee M18 FUEL 2825-20ST is the workhorse for big, overgrown lots.
| Product | Model | Max Torque / Feature | Best For | Buy |
|---|---|---|---|---|
 | Best Overall EGO ST1521S | 56V / 15-in. swath | Most yards, best all-around cut | View on Amazon |
 | Best for DEWALT Owners DEWALT DCST925M1 | 20V MAX / 13-in. swath | DEWALT 20V battery owners | View on Amazon |
 | Most Powerful Milwaukee 2825-20ST | M18 FUEL / 14 to 16-in. swath | Pros & large, overgrown lots | View on Amazon |
 | Best Value RYOBI RY40250 | 40V / 13 to 15-in. swath | Big features on a budget | View on Amazon |
 | Best Lightweight Greenworks 21302 | 40V / 13-in. swath | Small yards & first-time buyers | View on Amazon |
How We Picked These String Trimmers
We started with every major brushless cordless string trimmer sold by the five outdoor-power ecosystems most US homeowners actually buy into: EGO 56V, DEWALT 20V MAX, Milwaukee M18 FUEL, RYOBI 40V, and Greenworks 40V. Then we compared each one on the specs that change how fast you finish the yard: cutting swath (inches), line diameter (inches), line-feed system, shaft design, tool weight (lbs), and whether the kit includes a battery and charger.
Swath width matters more than voltage alone. A 15 to 16-in. swath clears open lawns far faster than a 13-in. head, while a narrower head with lighter line is easier to control around flower beds, mailboxes, and chain-link fences. We also favored push-button or automatic feed heads over fiddly manual rewinds, telescoping or adjustable shafts for users from 5 ft. 2 in. to 6 ft. 4 in., and kits that let a first-time buyer start cutting the day the box arrives.
1. EGO ST1521S — Best Overall
The EGO POWER+ ST1521S is the trimmer we recommend to most homeowners. Its 15-in. cutting swath and 56V brushless motor slice through weekly grass, thick crabgrass, and ankle-deep weeds without bogging down, and the patented POWERLOAD head solves the worst part of string trimming: reloading. Feed the 0.095-in. line through the head, press a button, and the trimmer winds it for you — no disassembly, no tangled spool.
The carbon-fiber split shaft keeps the tool stiff but light, telescopes to fit your height, and accepts EGO Multi-Head attachments if you later want an edger or pole saw. The kit ships with a 2.5Ah 56V battery and standard charger, and every EGO ARC Lithium battery you already own fits this tool.
EGO POWER+ 56V 15-Inch POWERLOAD String Trimmer Kit (ST1521S)
- Platform: 56V ARC Lithium, brushless motor
- Cutting swath: 15 in. with 0.095-in. dual line
- Feed: POWERLOAD automatic push-button rewind
- Shaft: Carbon-fiber split shaft, telescoping, 71.7-in. overall length
- Kit: 2.5Ah battery and charger included; about 7.3 lbs bare
What we like
- POWERLOAD reload is genuinely effortless
- 15-in. swath finishes open lawns fast
- Carbon-fiber shaft feels light and well balanced
- Huge 56V battery ecosystem for mower, blower, and more
Keep in mind
- Kit is bulkier to store than a 13-in. trimmer
- Best performance needs a 2.5Ah or larger battery
Kit with 2.5Ah battery and charger — check the live listing for the current kit configuration.
If you want one trimmer that handles a typical quarter-acre lot plus edging and fence lines without buying into a new battery system from scratch, the ST1521S is the safest pick. It is quieter than gas, starts with a trigger pull, and the 5-year tool warranty is among the strongest here.
2. DEWALT DCST925M1 — Best for DEWALT Owners
Own DEWALT 20V MAX batteries already? Stop reading and get the DCST925M1 kit. Its patented gear-drive transmission holds cut speed under load, so the 13-in. dual-line head keeps spinning through overgrowth instead of slowing the moment the grass gets tall. A variable trigger plus Hi/Lo speed switch lets you stretch runtime on light touch-ups or open it up along the fence.
At about 8.5 lbs and with a well-padded auxiliary handle, it balances nicely for users between 5 ft. 4 in. and 6 ft. 2 in. The 4.0Ah kit battery also powers your drill, blower, and every other 20V MAX tool on the truck.
The trade-off is swath: 13 in. takes more passes than the 15 and 16-in. picks on wide-open lawns. But for DEWALT households, sharing batteries across a dozen tools outweighs that — and the bump-feed head is simple to tap and go.
3. Milwaukee 2825-20ST — Most Powerful
The Milwaukee M18 FUEL 2825-20ST with QUIK-LOK is the pro-grade pick. It swings a 14 to 16-in. adjustable swath, spins up to 6,200 RPM, and its Easy Load head takes 0.080 or 0.095-in. line for everything from weekly touch-ups to waist-high ditch grass. Full-throttle response feels closer to a 25cc gas trimmer than to a typical homeowner electric.
The QUIK-LOK coupler is the real differentiator: the power head accepts Milwaukee bed-redefiner, edger, pole-saw, and hedge-trimmer attachments, so one motor covers the whole yard. Balance is excellent with a HIGH OUTPUT XC8.0 battery, and the adjustable front handle plus shoulder strap keep long sessions comfortable.
This is a bare tool, so budget for a battery if you are new to M18. For landscapers and owners of half-acre-plus lots who already live on the red platform, nothing else here cuts as aggressively.
4. RYOBI RY40250 — Best Value
The RYOBI 40V RY40250 delivers the longest feature list per dollar in this roundup: an adjustable 13 to 15-in. swath, REEL EASY+ bump-feed head that reloads in under a minute, variable-speed trigger, and EXPAND-IT attachment capability that accepts RYOBI and universal gas attachments. Narrow it to 13 in. for longer runtime around beds, widen it to 15 in. for open passes.
Runtime with a 4.0Ah battery stretches past an hour of mixed trimming, enough for most half-acre yards. And the 5-year tool warranty matches EGO for the best coverage in this guide.
Fit and finish trail Milwaukee and EGO — the shaft has a bit more flex, and the guard is wide. But if you want attachment versatility and a wide swath without paying pro-brand money, this is the value king.
5. Greenworks 21302 — Best Lightweight
The Greenworks 40V 21302 is the easiest trimmer here for small yards, townhome strips, and first-time buyers. The 13-in. auto-feed head advances 0.065-in. line on its own — no bumping — while the 90-degree rotating head converts to a walk-behind edger with a guide wheel for crisp sidewalk borders.
The telescoping shaft adjusts from 40 to 52 in., so users from about 5 ft. 2 in. to 6 ft. 4 in. can find a comfortable stance, and at roughly 9.3 lbs with the included 2.0Ah battery it is the lightest ready-to-cut kit in this guide. upkeep is nil: charge, snap in the battery, and go.
Single 0.065-in. line is not made for brush or acreage — it is a grass and light-weed tool. But for weekly touch-ups on lots up to about a quarter acre, its light weight and simple auto feed are genuinely pleasant to live with.
String Trimmer Buyer’s Guide
Voltage and platform
Voltage hints at power, but the battery family matters more. If you already own EGO 56V, DEWALT 20V MAX, Milwaukee M18, RYOBI 40V, or Greenworks 40V batteries, staying in that system saves real money — a spare high-capacity pack often costs nearly as much as a bare tool. Buying your first tool? EGO 56V and RYOBI 40V offer the deepest outdoor lineups for future mower, blower, and saw purchases.
Cutting swath (inches)
A 13-in. head is nimble around beds, fences, and play sets but takes more passes on open lawns. A 15 to 16-in. head can cut mowing-adjacent trimming time by a quarter or more on half-acre lots. Adjustable heads, like the RYOBI 13 to 15-in. and Milwaukee 14 to 16-in. designs, give you both: narrow for detail, wide for speed.
Line diameter and feed system
Thicker line cuts tougher weeds: 0.065-in. suits weekly grass, 0.080-in. handles mixed weeds and light brush, and 0.095-in. powers through crabgrass and ditch edges. For feed, automatic heads advance line for you, bump-feed heads advance with a tap on the ground, and EGO POWERLOAD winds new line at the push of a button. Avoid manual-wind heads if you hate downtime.
Shaft and ergonomics
Straight shafts reach under decks and along fences better than curved ones. Look for a telescoping shaft and an adjustable front handle so users of different heights share one tool comfortably. Split-shaft and attachment-capable designs (EGO Multi-Head, Milwaukee QUIK-LOK, RYOBI EXPAND-IT) turn one power head into an edger, pole saw, or hedge trimmer later.
Weight and runtime
Bare weights from 7 to 10 lbs sound similar on paper but feel very different after 30 minutes. Kits in this guide weigh roughly 8.5 to 10 lbs with battery installed. For runtime, a 2.0Ah pack covers small yards up to about a quarter acre, a 4.0Ah pack handles quarter to half-acre lots, and 5.0Ah and larger packs suit half-acre-plus or tall spring growth.
Warranty
EGO and RYOBI back these trimmers with 5-year tool warranties, while DEWALT, Milwaukee, and Greenworks typically offer 3-year coverage. Register your tool and keep the original battery and charger in the system — mismatched aftermarket packs can complicate warranty claims. Always confirm current terms on the manufacturer website.
The Bottom Line
For most homeowners, the EGO ST1521S is the best blend of cut width, easy reloading, and comfortable balance. Choose the DEWALT DCST925M1 if you already own 20V MAX batteries, the Milwaukee 2825-20ST for maximum muscle and attachment versatility, the RYOBI RY40250 for the most features per dollar, and the Greenworks 21302 for light, simple upkeep on small yards.
Pairing a new trimmer with a blower from the same battery family? Read our best cordless leaf blowers guide next.