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Getting a neat edge on your lawn shouldn’t require a trip to the gas station or a tug-of-war with a pull cord. The best 40-volt string trimmers give you real cutting muscle, instant start, and none of the noise or fumes that come with gas. This category has matured to the point where a well-chosen battery-powered trimmer genuinely replaces a gas machine for most yards.
I’m Mo Maruf — the founder and writer behind The Tools Trunk. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Below, you will find hands-on reviews of seven trimmers that cover different needs and budgets, including the one that strikes the best balance of power, weight, and runtime in today’s 40 volt string trimmer market.
Our Picks at a Glance
How To Choose The Best 40 Volt String Trimmer
Your yard’s needs and your tolerance for swapping batteries are what drive the real decision here. A trimmer that works for a manicured quarter-acre might feel under-gunned on a larger property with heavy brush. Focus on these three factors, and you will land on the right machine.
Cutting Width and What It Costs You
A wider cutting swath, measured in inches, means you cover more ground per pass. A 17-inch head will make quick work of a fence line compared to a 13-inch head, saving you time and walking steps. The trade-off is usually weight and battery draw, but for a larger lawn, the wider path is worth it.
Battery Amp-Hours (Ah) Are Your Fuel Tank
The “Ah” rating on a battery tells you how long it runs before needing a recharge. A 2.0Ah battery is fine for a small lot of light trimming. A 4.0Ah battery can handle a full hour of steady work, including tackling thicker weeds. If you have a big yard, look for a kit that includes a higher-capacity battery or comes with two batteries so you can swap while one charges.
Line Thickness and Feed System
The cutting line thickness matters for durability. A.095-inch line is heavier and stands up to weeds and brush without snapping as easily as a thinner.080-inch line. The feed system is either a “bump feed,” where you tap the head on the ground to release more line, or an auto-feed system. Bump feed is widely considered the most reliable and least frustrating method.
Quick Comparison
| Model | Best For | Cutting Width | Weight | Battery Included | Amazon |
|---|---|---|---|---|---|
| Kobalt 40-Volt Max 15-in★ Best Overall | Light Duty / Add-On | 13 Inches | 11.4 Pounds | No (bare tool) | Amazon |
| RB 17″ 40V TrimmerBest Value Pick | Best Overall Value | 17 Inches | 6.6 Pounds | Yes, 2.0Ah | Amazon |
| RYOBI 40V 15″ Bare Tool | Existing Ryobi Owners | 13 Inches | 11 Pounds | No (bare tool) | Amazon |
| SKIL Trimmer & Blower Combo | Best Combo Value | 14 Inches | — | Yes, 2.0Ah | Amazon |
| SKIL PWR CORE 40 Multi-Head | Premium Performance | 16 Inches | 14.5 Pounds | Yes, 4.0Ah | Amazon |
| RYOBI Whisper Series 17″ | Ultra-Quiet Power | 17 Inches | 12 Pounds | No (bare tool) | Amazon |
| Worx WG186 Nitro | Heavy Brush & Attachment Use | 15 Inches | 11.9 Pounds | Yes, 2 x 4.0Ah | Amazon |
In‑Depth Reviews
1. Kobalt 40-Volt Max 15-in Straight Cordless String Trimmer (Bare Tool)
Our pick — 4.5★ from 400+ verified ratings; the strongest balance of quality and price.
A 13-inch trimmer for the Kobalt owner who wants a second tool on the same battery system.
This is the lightest option for anyone already invested in Kobalt’s 40V Max battery platform. The 13-inch cutting swath is the smaller side of standard, and the trimmer spins at 6000 RPM, which is enough to keep the line cutting through most weeds. Owners confirm it “will cut through most weeds” and find it effective for smaller jobs on a single battery. The straight shaft design gives you better reach under shrubs and around obstacles than a curved shaft.
At 11.4 pounds, it is not the lightest trimmer in this roundup, but it is well-balanced and owners find it manageable for a full yard. The battery life and weight both get mixed feedback: some find it light, others heavier than expected. It is a solid, affordable upgrade path for anyone who already owns Kobalt 40V tools. If you are starting from scratch, the lack of an included battery and charger makes the RB a much better entry point, especially given the RB’s wider 17-inch cutting width and lighter 6.6-pound weight.
Ecosystem move: For Kobalt 40V owners, this is a cost-effective bare-tool trimmer that does the job. But at 11.4 pounds with a 13-inch swath, it falls short of the RB’s 6.6 pounds and 17-inch width.
Grab this if: you already own Kobalt 40V batteries and want a trimmer to match your existing mower or blower.
pass on it if: you are starting fresh — the RB gives you a wider cut, lighter weight, and a battery for the same or less money.
2. RB 17″ 40V Cordless String Trimmer
The lightweight that punches well above its weight class.
What you get here is a 17-inch cutting swath — a full four inches wider than standard 13-inch models — which means you clear more grass with each sweep and finish the job noticeably faster. It also uses a.095-inch heavy-duty dual line that chews through thick weeds without snapping, and buyers report it delivers real gas-like power even on its low speed, cutting through foot-tall grass as if it were nothing.
The RB trimmer weighs just 6.6 pounds, making it the lightest in this roundup by a significant margin — 4.8 pounds lighter than the comparable Kobalt model. It also converts into an edger with a simple head rotation, no tools required. The trade-off is that battery life gets mixed feedback; a single 2.0Ah battery handles a typical yard, but heavy users would want a spare. As owners mention, this thing is “powerful on low speed, cuts foot-tall grass like gas/corded units.”
Why it wins
- 17-inch cutting width beats the 13-inch Kobalt and RYOBI trimmers, saving you time.
- At 6.6 pounds, it is lighter than any other trimmer here, reducing arm fatigue.
- Includes a 2.0Ah battery and charger plus four spare spools of line.
The honest limit
- The included 2.0Ah battery gives moderate runtime; consider a larger Ah battery for big properties.
- Assembly instructions are a bit sketchy, according to some owners.
Grab this if: you want the widest cutting path in the lightest package, with battery and charger included, for a very fair price.
Hold off if: you need all-day runtime on a single charge — you will want to pair it with a higher-capacity 40V battery.
3. SKIL PWR CORE 40 Brushless 40V Multi-Head System, 16-Inch
A bigger swath and a bigger battery for serious yards.
If your lawn runs to an acre or more, this SKIL brings the essentials: a 16-inch cutting swath that covers ground fast, a 4.0Ah battery that owners say lasts about 45 minutes of hard work, and a digital brushless motor that delivers consistent power without the maintenance of gas. The included battery uses PWR CORE 40 technology, which wraps each cell in cooling material for longer life and runtime.
This is a multi-head system, meaning the power head accepts SKIL attachments for edging, blading, or pole saw work — a big space-saver if you like a single power source for multiple tools. The Twist Load head makes restringing simple: insert the line and twist. The catch is the weight: at 14.5 pounds, it is the heaviest trimmer here, and owners note it lacks an optional shoulder strap for balance. Still, the consensus is that it handles up to three acres and chews through tough, thick grass with authority.
Solid investment: The 16-inch cutting path beats the 13-inch standard trimmers, and the 4.0Ah battery gives you real runtime. It is a premium tool for a premium property, but you will feel the weight after an hour. No included comfort strap is a miss.
Best for: owners of larger properties who value power and attachment flexibility over a featherlight tool.
Think twice if: you need to carry the trimmer for long periods without a strap — the weight is noticeable compared to the RB or Kobalt.
4. SKIL PWR CORE 40 Brushless 40V 14-Inch Trimmer and Blower Combo
Two essential yard tools in one box, for less than you would pay separately.
This SKIL combo kit gives you a 14-inch string trimmer and a leaf blower that pushes up to 460 CFM at up to 120 MPH, all powered by a shared 2.0Ah battery and 60W charger. The trimmer uses a dual-line bump feed head and a two-speed selector, letting you dial in more power or longer runtime. The blower has variable speed with a turbo boost for heavy piles. Owners praise it as light enough for a 61-year-old to use comfortably.
The kit is also rated IPX4 for weather resistance, meaning it holds up in damp conditions without issue. Twist load makes restringing simple. The obvious trade-off is you get one 2.0Ah battery to share between two tools, so you will likely want a second battery for extended sessions. Owners agree the combo earns a strong “worth the money” verdict, with one calling the trimmer “amazing” for eating through weeds.
Cost-saving move: A trimmer and a 460 CFM blower in one kit is a great deal for a single-battery household. The 14-inch cutting width is standard, but the blower’s power is the real standout feature here.
Reach for this if: you need both a trimmer and a blower and want to save money by buying them together with one battery.
Look elsewhere if: you have a very large yard — a single 2.0Ah battery will not finish trimming and blowing in one go.
5. Worx WG186 Nitro 40V 15″ String Trimmer
Gas-like power in a cordless package, ready for brush and attachments.
The Worx Nitro line is engineered for gas-like power, and this 15-inch trimmer delivers with a brushless motor that runs 50% longer and is 25% more powerful than standard motors, per the manufacturer. It comes with two 4.0Ah batteries and a dual-slot charger, which is a serious advantage for large properties because you can swap batteries without downtime. The DriveShare split-shaft system also accepts most other brand’s attachments for jobs like edging or brush cutting.
Owners confirm it powers through tall grass, weeds, and even small woody plants. The dual-exit cutting head bumps to feed. The honest feedback is that the trimmer is heavy — 11.9 pounds — and the included shoulder strap is considered inadequate; many owners recommend a full-body harness instead. Battery life is also a well-documented mixed point: a 4.0Ah battery lasts roughly 30-40 minutes at full throttle, which is average for this class, but several owners want more. Stock.0905-inch line works, but some owners switch to.080-inch square line for better cutting and slightly longer battery life.
What you get
- Comes with two 4.0Ah batteries and a charger — the most generous battery bundle in this roundup.
- Variable speed trigger with ECO mode lets you manage runtime.
- Attachment-capable and fits most other brand’s trimmer attachments.
What to know
- At 11.9 pounds, it is heavy for its class; a shoulder harness upgrade is almost necessary.
- The variable speed trigger lacks a lock-on, which requires a constant finger press.
Best for: anyone who needs the runtime of two batteries and the flexibility of a multi-attachment system for a larger, brush-heavy property.
skip it if: weight is your primary concern — the RB trimmer is far lighter for standard lawn trimming.
6. RYOBI 40V HP Brushless Whisper Series 17″ String Trimmer
A 17-inch carbon-fiber shaft that stays whisper-quiet while you work.
This RYOBI brings the same 17-inch cutting width as the RB trimmer but adds a carbon fiber shaft that keeps the weight at a manageable 12 pounds while dampening vibration. As part of the Whisper Series, it runs noticeably quieter than a gas machine — customers note they were able to ditch their old gas weed eater entirely after using this one. It uses a variable speed trigger for precise control and the bump-feed head is easy to reload.
Note that this is a bare tool: no battery or charger are included, so it is best suited for buyers who already own RYOBI 40V batteries. The few owners who reviewed it mention it has plenty of power and is used weekly without issue. Some noted initial assembly quirks, like missing screws, so check the box carefully upon arrival. If you already have RYOBI gear, this is a very compelling upgrade for the wider cutting path and reduced noise.
Best for the RYOBI family: If you already own RYOBI 40V batteries, this bare tool gives you a 17-inch cutting swath with the Whisper Series’ quiet operation at a reasonable cost.
Grab this if: you are already in the RYOBI ecosystem and want the widest cutting path they offer in a quiet package.
Think twice if: you need a battery and charger included — you will have to buy those separately, which pushes the total cost higher than the RB kit.
7. RYOBI 40V Attachment Capable 15″ String Trimmer (Bare Tool)
A 13-inch trimmer that promises up to 71 minutes of runtime per charge.
This RYOBI bare tool delivers a 13-inch cutting swath — the standard size for smaller-to-medium lawns — and is rated for up to 71 minutes of runtime when paired with a 40V 4Ah battery. That is a concrete runtime figure that is rare to see on a spec sheet and gives you a realistic expectation for how long you can work. The brushless motor is claimed to be more powerful than a 21cc gas trimmer, making it a true gas replacement for many.
It is also EXPAND-IT attachment capable, so you can swap on an edger or brush cutter attachment. Owners who already use RYOBI 40V tools appreciate the quality and the reliable bump feed head. The reliability is noted as mixed in reviews, with some triggers failing, but the overall quality rating is positive. At 11 pounds, it sits mid-pack for weight. This is a strong add-on for anyone who already owns RYOBI batteries and wants a dependable trimmer for weekly maintenance.
Smart add-on: For existing RYOBI 40V battery owners, this is a well-priced, reliable workhorse. The 71-minute runtime claim (with a 4Ah battery) is a major buying point.
Best for: RYOBI ecosystem owners who need a dependable, attachment-capable trimmer for standard yard upkeep.
Hold off if: you do not own any RYOBI batteries — the total cost of adding a battery and charger makes it less attractive than all-in-one kits.
Understanding the Specs
Cutting Width (Swath)
This is the diameter of the circle your trimmer line spins in. A wider swath — 17 inches vs. 13 inches — means each pass covers more ground, so you trim your lawn in fewer passes. It is a direct trade-off against weight and battery drain, but for a standard quarter-acre lot, 15 to 17 inches will save you noticeable time.
Battery Amp-Hours (Ah)
Amp-hours measure the “fuel tank” of your battery. A 2.0Ah battery is enough for a small yard with light grass. A 4.0Ah battery can run a trimmer for 30 to 45 minutes of steady work, including heavier weeds. If you have a large property, look for a kit that includes two batteries or a higher Ah rating so you are not stuck waiting for a recharge.
FAQ
Can a 40V string trimmer really replace a gas trimmer?
How long does a 40V trimmer battery last on a full charge?
What does “bare tool” mean?
Will a 40V trimmer fit attachments from other brands?
What is the difference between.080 and.095 trimmer line?
Is a 13-inch cutting width enough for a standard lawn?
How do I load the line on a bump feed head?
What is a brushless motor and why does it matter?
Can I use a larger battery from the same brand to get more runtime?
What is the best way to store a 40V battery?
Final Thoughts: The Verdict
For most people, the 40 volt string trimmer winner is the RB 17″ Cordless Trimmer because it gives you the widest cutting path, the lightest weight, and a complete kit with battery at a price that beats the competition. If you want the raw power and battery capacity for a larger property, grab the SKIL PWR CORE 40 Multi-Head with its 4.0Ah battery and 16-inch swath. And for anyone who needs a trimmer and blower in one box, the SKIL Trimmer and Blower Combo is the one to reach for.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of July 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
As an Amazon Associate, The Tools Trunk earns from qualifying purchases. This does not affect which products we feature.