5 Best 40v String Trimmer: Top Choices and Important Features

Finding the best 40v string trimmer usually comes down to balancing cutting power, battery convenience, line control, and the size of the property. For most homeowners, the Greenworks 40V 12 in String Trimmer & is the strongest overall choice because it combines a trimmer with a blower, includes a 2.0Ah battery and charger, and fits into a broader 40V tool system. The BLACK+DECKER 40V Max Cordless Sweeper & String is the clearest alternative if automatic line feeding and a battery-level indicator matter most.

The other three options serve different priorities. The 40V 14″ String Trimmer offers a brushless motor, thicker .095-inch line, blades, shoulder support, and two batteries. The RYOBI 40-Volt Lithium-Ion Cordless Attachment Capable Stri emphasizes versatility through its Expand-It connection and adjustable cutting width. The Kobalt 40-Volt Max 15-in Straight Cordless Bare is worth considering mainly for shoppers who already own a compatible battery.

This roundup compares the five tools by cutting equipment, included power components, handling features, attachment or battery compatibility, and the practical limitations a buyer should understand before ordering. Product rank also considers how complete the package is for a typical homeowner rather than focusing only on raw cutting width.

Best 40v String Trimmer at a Glance

1. Greenworks 40V 12 in String Trimmer &

Check Price on Amazon

The Greenworks 40V 12 in String Trimmer & earns the top position because it is a well-rounded yard-maintenance package rather than only a trimmer. The combo includes a 40V trimmer, a blower, a 2.0Ah battery, and a charger. That makes it particularly useful for homeowners who need to define lawn edges and then clear clippings, leaves, or loose debris from sidewalks and driveways during the same session.

Its 12-inch cutting width is manageable around flower beds, fences, garden borders, and other areas where precision matters. The .065-inch automatic-feed line is intended for routine grass and weed trimming, while the supplied information describes the head as capable of cutting through weeds up to 1 inch thick. A three-year head warranty is another useful ownership detail, especially for buyers who expect to use the trimmer regularly.

The included blower adds practical value. It is rated at up to 110 MPH and 390 CFM, with cruise control for maintaining airflow while clearing hard surfaces or gutters. The 40V battery also belongs to a wider Greenworks ecosystem that includes more than eight tools, so an owner may be able to expand into mowing, hedge trimming, or wood-cutting equipment without changing battery platforms.

There are trade-offs. The 2.0Ah battery has a stated 60-minute charge time, and the actual work session will depend on how heavily the trimmer and blower are used. A 12-inch path is controlled but not especially wide for large open lots. The reported 8-pound balanced design is helpful for edging and detail work, but users with heavy brush or extensive acreage may want a thicker-line model. It is a particularly sensible purchase for ordinary residential cleanup, provided the buyer wants both tools and plans to stay within the Greenworks 40V platform.

2. BLACK+DECKER 40V Max Cordless Sweeper & String

Check Price on Amazon

The BLACK+DECKER 40V Max Cordless Sweeper & String ranks second because it offers a highly convenient trimmer-and-sweeper combination with several homeowner-friendly controls. The package includes the LST140 trimmer, LSW40 sweeper, a 40V battery, and a charger. It is a strong alternative to the Greenworks combo for buyers who place more emphasis on automatic line management and battery-status visibility.

The trimmer uses a POWER DRIVE high-torque transmission, which is designed to deliver clean, fast cuts through ordinary lawn growth. Its automatic feed spool, known as AFS, feeds line as needed rather than requiring the operator to bump the head or manually advance the line as frequently. That can make routine edging less interrupted, particularly for users who prefer a simple start-and-trim workflow.

The companion sweeper reaches up to 130 MPH and is intended for moving leaves and debris from hard surfaces. Because it is a sweeper rather than a heavy-duty blower description, buyers should think of it primarily as a cleanup tool for driveways, patios, walkways, and similar areas. The low-noise design is useful in neighborhoods where early-morning or evening yard work needs to be less disruptive.

A state-of-charge indicator shows the remaining battery level, which is a small but meaningful advantage over systems that provide little warning before power runs out. The package also includes a two-year limited warranty. At the same time, the supplied information does not identify a cutting width or a thicker brush-cutting setup, so this combo is better suited to grass, edging, and general residential weeds than demanding brush clearing. Buyers should also remember that one battery powers both tools. If the trimmer and sweeper will be used for a long cleanup session, a spare compatible battery may be worth considering. This is the better fit for someone who values straightforward line feeding and clear battery monitoring over a larger cutting path.

3. 40V 14″ String Trimmer

Check Price on Amazon

The 40V 14″ String Trimmer takes third place because its equipment list is unusually ambitious for a cordless trimmer package. It includes a 3T blade, a 40T alloy blade, a string spool head, and a replacement line roll. Both line components use thick .095-inch line, giving this model a more substantial cutting setup than the lighter-duty .065-inch options in the first two positions. That makes it attractive for buyers who regularly move beyond lawn edges into thicker weeds, brush, and pathway vegetation.

A brushless motor supplies the stated 40V output, while two included 20V 4.0Ah batteries connect in series. The package also includes a dual-port charger. Both batteries are described as charging within two hours, with up to 60 minutes of operation on low speed or 40 minutes on high speed. Actual runtime will vary with the selected attachment, vegetation, and cutting load, but the inclusion of two batteries gives the owner more flexibility than a single-battery kit.

The tool is also described as compatible with Makita 18V LXT tools. That may appeal to shoppers already using that battery ecosystem, although the package includes its own two batteries and charger. Buyers should verify the exact compatibility details for their particular Makita tools and batteries before assuming every component can be interchanged.

Handling features include an adjustable auxiliary handle, a padded shoulder strap, and a shaft that folds at the center for storage or vehicle transport. The foldable design is useful for garages and sheds where a full-length shaft is inconvenient. The principal trade-off is complexity: blades and string heads require more setup and more attention to safe operation than a basic automatic-feed trimmer. The tool is a better match for users who will actually use the thicker line and blade attachments, while someone trimming only soft grass may prefer a lighter, simpler combo. Before operating, inspect the selected head, secure the shaft hinge, and use the shoulder strap as intended.

4. RYOBI 40-Volt Lithium-Ion Cordless Attachment Capable Stri

Check Price on Amazon

The RYOBI 40-Volt Lithium-Ion Cordless Attachment Capable Stri ranks fourth because its central advantage is expandability rather than a large set of included cutting attachments. It accepts RYOBI Expand-It attachments and other universal gas attachments, allowing one powerhead to serve more than one landscaping purpose. For an owner who already has compatible attachments, or who wants to add them gradually, that capability can save storage space and avoid buying a separate motor for every task.

The included package contains a 40V lithium-ion high-capacity battery, a charger, and the trimmer. The charger is described as taking 90 minutes, giving the owner a predictable charging routine between yard-care sessions. A variable-speed trigger allows the operator to adjust cutting control rather than running the head at one fixed level all the time. That can be useful when moving between delicate areas near plants and heavier grass along open edges.

Another notable feature is the adjustable cutting width. It can be set from 13 inches to 15 inches. The narrower setting can help conserve runtime and provide more control, while the wider setting covers more ground per pass. This flexibility gives the RYOBI a different sort of versatility from the multi-tool kits above: instead of including a blower or multiple blades, it adapts the trimmer’s working width and accepts additional attachments.

The Reel-Easy bump-feed string head is designed for faster, easier line reloading, but it still requires the operator to manage line advancement in use. This model may not be the ideal choice for someone who wants automatic feeding or a complete trimmer-and-blower package out of the box. Compatibility is the key buying consideration. Confirm that existing attachments use the supported Expand-It or universal connection before ordering, and remember that attachment weight and cutting demands can affect balance and runtime. It is most appealing to homeowners building a RYOBI yard-tool system and wanting one battery-powered powerhead for several future jobs.

5. Kobalt 40-Volt Max 15-in Straight Cordless Bare

Check Price on Amazon

The Kobalt 40-Volt Max 15-in Straight Cordless Bare is fifth largely because the supplied product information is limited and the tool is sold as a bare tool. Its 15-inch cutting width is the largest stated width among the ranked trimmers, which could help cover open lawn edges efficiently. However, the battery is not included, so the apparent convenience of a cordless package depends heavily on whether the buyer already owns the required Kobalt 40V battery and charger.

A bare-tool purchase can be sensible for an established battery-platform owner. Someone who already has compatible Kobalt 40V equipment may be able to add this trimmer without paying for another battery and charger. That also makes it easier to keep a spare battery available for longer sessions. For a first-time cordless-tool buyer, though, the missing power components are a significant consideration because the owner must obtain them separately before the trimmer can be used.

The wider 15-inch path suggests an emphasis on covering more ground per pass, but the available data does not provide details about line diameter, feed method, motor design, variable-speed control, included accessories, or warranty coverage. Those omissions make it difficult to compare its cutting behavior or maintenance requirements with the other four products. They also mean shoppers should carefully review the current package contents and compatibility information before completing a purchase.

This model may suit a Kobalt owner who wants a straight cordless trimmer with a generous stated width and does not need a blower, extra blades, or a new charging kit. It is less attractive for someone starting from zero, especially if the total cost of acquiring a battery and charger narrows the gap with a complete kit. Confirm the exact battery requirement, check whether your existing charger supports that battery, and inspect the seller’s current specifications because the supplied information does not establish those details. Its rank reflects that uncertainty, not a claim that a bare tool cannot be useful.

How to Choose the Best 40V String Trimmer

A 40V label is a helpful starting point, but it does not tell the whole story. Two trimmers with the same nominal voltage can feel very different because of their cutting width, line diameter, feed mechanism, motor design, included battery capacity, balance, and intended vegetation. The right choice is the one that matches the work you actually do, not simply the model with the largest number on the package.

Start with the type of growth you need to cut

For ordinary lawn edging, soft weeds, and grass around sidewalks, a standard string head may be all you need. In that situation, a lighter 12-inch tool can be easier to guide around trees, garden borders, fences, and flower beds. The Greenworks and BLACK+DECKER packages are especially practical for this kind of maintenance because both combine trimming with a hard-surface cleanup tool.

Thick weeds and brush require a more substantial setup. The 40V 14″ model stands apart by including .095-inch line and two blade options. Thicker line can be useful when the vegetation is demanding, but it can also increase the cutting load and make careful handling more important. A buyer should not choose a blade-equipped model merely because it sounds more powerful; choose it when the extra capability corresponds to real work on the property.

For a large, mostly open lawn, a wider cutting path can reduce the number of passes. The RYOBI adjusts from 13 to 15 inches, while the Kobalt lists a 15-inch path. Wider is not automatically better around delicate landscaping. It can be less precise in tight spaces, and the physical size of the head may be less comfortable for detail work. Consider whether your yard consists mainly of open edges or many obstacles before prioritizing width.

Understand what the battery package includes

Battery inclusion is one of the biggest differences between these products. Greenworks, BLACK+DECKER, the 40V 14″ model, and RYOBI are supplied as kits with a battery and charger according to the provided information. The Kobalt is explicitly a bare tool, so it is aimed at an owner who already has the appropriate 40V power equipment.

A battery’s amp-hour rating can provide useful context, but it is not a promise of a fixed runtime. Cutting thick vegetation, using a blade, running at high speed, or operating a second tool from the same battery can reduce the usable session. The 40V 14″ model provides the clearest runtime information in this group: up to 60 minutes at low speed or 40 minutes at high speed, using its two batteries under the stated conditions.

Charging time matters if you have only one battery. Greenworks lists a 60-minute charge time for its 2.0Ah battery, RYOBI lists a 90-minute charger, and the 40V 14″ package says both batteries charge within two hours using the dual-port charger. These figures help you plan, but they should not be treated as directly interchangeable measurements because battery capacities and charging arrangements differ.

If you want to trim and blow debris in one continuous session, check whether the kit contains one battery or more and whether the tools can share it. The Greenworks and BLACK+DECKER combos each pair a trimmer with a cleanup tool, but a single battery may need to be swapped or recharged between tasks. An extra platform-compatible battery can be more useful than a larger cutting width when the property requires extended maintenance.

Compare line-feed systems and line size

Line management affects how much attention the tool needs during use. The BLACK+DECKER uses an automatic feed spool that feeds line as needed. That is appealing to someone who dislikes stopping to bump the head or manually advance line. It can also make the trimming rhythm more predictable for a first-time cordless-tool owner.

The RYOBI uses a Reel-Easy bump-feed head. Bump-feed systems are familiar to many trimmer users, but they require a deliberate action to advance line. The Greenworks product uses a .065-inch automatic-feed line according to the supplied features. Since the wording describes the line as automatic-feed, verify the exact replacement-head and spool instructions for your model when maintenance becomes necessary.

The 40V 14″ model is supplied with .095-inch line and a string spool head, along with replacement line. Larger line can be better suited to heavier weeds, but replacement line must match the head’s requirements. Do not assume that any spool or diameter will work simply because it fits physically. Use the manufacturer’s stated size and loading method, particularly when switching between a string head and a blade.

Line-feed convenience should be weighed against the vegetation. Automatic feed is attractive for routine grass work, while a heavy-duty setup with blades may be more appropriate for thick growth. If most of your trimming is light edging, a complicated multi-head system may add storage and setup obligations without delivering a meaningful benefit.

Look at the whole tool ecosystem

A battery platform becomes more valuable as your outdoor-tool collection grows. Greenworks describes its 40V battery as supporting more than eight tools, including mowing, hedge trimming, and wood-cutting equipment. BLACK+DECKER buyers may also value the included sweeper and the convenience of having the battery level shown on the pack or tool system.

RYOBI’s strongest ecosystem feature is its attachment capability. The powerhead accepts RYOBI Expand-It attachments and other universal gas attachments. That can let one motor handle multiple tasks, but compatibility must be checked carefully. “Universal” does not mean every attachment from every manufacturer will fit every connection, and an attachment that fits mechanically may still change the tool’s balance or operating demands.

The 40V 14″ model is described as compatible with Makita 18V LXT tools while producing 40V output through two 20V batteries in series. This is a particularly important detail to verify before purchase. Battery-platform wording can refer to physical compatibility, included battery architecture, or tool-system marketing, and those are not always the same thing. Use the exact battery and charger instructions supplied for the model rather than combining components based only on voltage labels.

The Kobalt is the simplest ecosystem decision: it makes the most sense when you already own the required Kobalt 40V battery and charger. If you do not, calculate the complete system cost instead of comparing the bare-tool price alone. A complete kit may be the better value when it includes the battery, charger, and a second yard tool.

Balance, shaft design, and working comfort

Weight is only one part of comfort. Balance determines how much effort is needed to keep the head at the right height and angle. The Greenworks package describes an 8-pound balanced design, which can be useful for edging and detail work. The 40V 14″ model adds an adjustable auxiliary handle and padded shoulder strap to distribute its load during longer or heavier jobs.

A shoulder strap is especially relevant when using a wider cutting head, thicker line, or blade. It can reduce the sensation of holding the entire tool with the arms, but it does not replace safe control. Adjust the strap and auxiliary handle before starting so the head remains stable and the controls are easy to reach.

The 40V 14″ model also folds at the center of the shaft using a quick-release hinge. That is a meaningful storage and transport benefit for people with small garages or vehicles. Folding designs introduce an additional connection that should be checked before operation. Make sure the hinge is fully secured and that the shaft is rigid before engaging the motor.

A straight shaft can provide a familiar reach and is often convenient along long edges, but the supplied data does not give enough detail to compare the shaft geometry of every model here. Whenever possible, prioritize control and fit over a small difference in listed width. A trimmer that is easy to guide is more useful than one that technically covers more ground but causes fatigue or makes precise edging difficult.

Decide whether a combo package is useful

Combo kits can simplify yard care because trimming and cleanup happen in sequence. After cutting grass along a driveway, patio, or walkway, a blower or sweeper removes clippings from the finished surface. Greenworks provides a blower rated at 110 MPH and 390 CFM, while BLACK+DECKER provides a sweeper rated up to 130 MPH. These numbers are not a direct apples-to-apples performance comparison because air volume and tool design also affect how debris moves.

Think about the surfaces you maintain. Hard surfaces such as concrete, pavers, patios, and driveways are where a cleanup tool is most immediately useful. If you already have a blower, buying another combo may add cost and duplicate equipment. In that case, a trimmer with a larger cutting setup, attachment capability, or extra battery may be more practical.

One battery serving two tools can also create a scheduling issue. If the battery is nearly depleted after trimming, the cleanup tool may have to wait. A second battery solves that more effectively than repeatedly switching between tools, but it increases ownership cost. A combo is most compelling when both included tools replace equipment you would otherwise need to buy separately.

Match the tool to your maintenance habits

Cordless trimmers are convenient because they avoid fuel mixing, engine starting, and extension cords. They still need routine care. Before each session, inspect the cutting head, guard, shaft connection, handle, and battery contacts. Remove wrapped grass or vines only after the tool is switched off and the battery is removed. For models using blades, check the blade and fasteners for damage before operation.

Keep replacement line available before the old spool runs out. Automatic-feed and bump-feed heads both become frustrating when the correct replacement line is not on hand. Use the recommended diameter and loading method, and avoid forcing an oversized line into a head designed for a thinner size.

Battery care is equally important. Charge batteries with the supplied or approved charger, keep contacts clean and dry, and store the battery according to the manufacturer’s instructions. Do not leave a battery exposed to unnecessary heat or moisture. If you own a combo kit, label or organize batteries if several tools use the same platform so a charged pack is ready when the yard needs attention.

Noise is another practical consideration. The Greenworks product describes a 67dB whisper start, and the BLACK+DECKER package is described as low noise. Quieter operation does not eliminate the need for eye and hearing protection or courtesy toward neighbors, but it may make cordless trimming more comfortable in residential settings.

Consider the limitations of the available specifications

Product descriptions do not always provide the same level of detail. The Greenworks and BLACK+DECKER kits list multiple tool and battery features, while the Kobalt listing supplied here gives no feature details beyond its 15-inch straight cordless bare-tool description. That does not prove the Kobalt lacks useful features; it means a careful shopper should verify them from the current listing or manufacturer documentation.

The same caution applies to runtime and compatibility. Runtime depends on vegetation, speed, line size, head type, temperature, and battery condition. A published maximum should be used for planning rather than treated as a guarantee for heavy cutting. Compatibility claims should be checked against the exact battery, charger, attachment, and tool model numbers.

Warranty coverage can also vary by component. Greenworks lists a three-year head warranty, while BLACK+DECKER lists a two-year limited warranty. These statements should not be assumed to cover every part or every type of damage. Keep the purchase documentation and read the current warranty terms, especially if you expect frequent use.

FAQ About the Best 40V String Trimmer

Is a 40V string trimmer powerful enough for normal residential work?

Yes, a 40V cordless trimmer is generally positioned for routine residential grass, lawn edging, and weed maintenance. The exact capability depends on the head and line. The ranked choices range from .065-inch automatic-feed setups to a .095-inch multi-attachment model, so buyers should match the tool to the vegetation rather than relying on voltage alone.

Which 40V string trimmer is the best complete kit?

The Greenworks 40V 12 in String Trimmer & is the strongest complete package in this ranking because it includes a trimmer, blower, 2.0Ah battery, and charger. It also provides access to a broader Greenworks 40V ecosystem. The BLACK+DECKER combo is a close alternative with a sweeper, automatic feed spool, battery indicator, battery, and charger.

Is the BLACK+DECKER automatic feed better than a bump-feed head?

Automatic feed is more convenient for users who want line to advance without tapping the head. A bump-feed system, such as the RYOBI Reel-Easy setup, gives the operator direct control over when line advances. Neither system is universally better; the choice depends on whether convenience or hands-on control is more important to you.

Should I choose a wider 15-inch cutting path?

A wider path can reduce passes across open lawn edges, but it may be less convenient around trees, beds, posts, and delicate plants. The RYOBI offers an adjustable 13-to-15-inch width, while the Kobalt lists a 15-inch width. For detailed edging, a smaller or adjustable path may be easier to control.

Are the included batteries interchangeable across all 40V trimmers?

No. Voltage alone does not make batteries interchangeable. Batteries normally need to match the manufacturer’s platform, physical connection, and approved charger. Greenworks, BLACK+DECKER, RYOBI, Kobalt, and the 40V 14″ model should be treated as separate systems unless the manufacturer specifically confirms compatibility.

Is the Kobalt bare tool a good deal for a new buyer?

It may be useful for someone who already owns the required Kobalt 40V battery and charger. For a new buyer, the additional battery and charger cost must be included in the comparison. Because the supplied listing provides few feature details, verify the complete package, battery requirement, and warranty before choosing it over a complete kit.

When is a blade-equipped 40V trimmer worth choosing?

A blade-equipped model is most appropriate when the property includes thicker weeds, brush, or dense pathway vegetation that exceeds ordinary grass trimming. The 40V 14″ model includes a 3T blade, a 40T alloy blade, and a .095-inch string head. Blades require careful setup, protective equipment, and attention to the manufacturer’s operating instructions.

Final Verdict

The Greenworks 40V 12 in String Trimmer & is the best overall choice for most homeowners because its trimmer, blower, battery, charger, manageable width, and 40V ecosystem create a balanced package. Choose the BLACK+DECKER 40V Max Cordless Sweeper & String when automatic line feeding and battery-status visibility are more important. The remaining models make more sense for specific needs: heavy-duty attachments, Expand-It versatility, or an existing battery platform.