String Trimmer vs Edger: What Each Tool Does and Which You Need

String trimmer vs edger comes down to the cutting part: a trimmer spins nylon line to cut grass and keep an edge tidy, while an edger’s steel blade cuts a clean vertical wall of soil along a walk or bed. Most yards need the trimmer first and an edger only once the border has grown over.

I keep the grass edge along a gravel yard, the house paths and the concrete work pad, and I have cut those borders with line and, on the paved ones, with a blade. Below I cover how each tool cuts, what a trimmer can and cannot do on an edge, the safety differences, and which one suits your yard.

The Short Answer on String Trimmer vs Edger

A string trimmer cuts grass with a spinning nylon line, and an edger cuts the ground with a steel blade. That one difference sets what each tool can do. The trimmer handles grass at fences, trunk bases and beds. A lawn edger draws a straight vertical face between lawn and pavement.

Makers say the same in their manuals. According to Greenworks, its edger is used to cut around the edge of driveways and sidewalks, and it is not meant for hedges, shrubs, bushes or flowers. Ryobi limits its edger to sidewalks, driveways and flower beds. An edger does not replace a trimmer. It does one job. For hedges, my hedge trimmer and string trimmer comparison shows which tool cuts what.

How Each Tool Cuts

The cutting part of each tool sets its limits, so start there. One is soft and held flat. The other is rigid and stands on its edge.

Nylon Line Held Flat on a String Trimmer

A motor spins a head at the bottom of a shaft, and the tip of the nylon line does the cutting. A guard behind the head helps deflect debris away from you, and a small blade on the guard trims the line to length. According to EGO, the very tip of the line should do the cutting, with the line held parallel to the ground. Line is soft, so it wears fast on stone, brick and curbs, and the same maker warns that bark and fence posts are easy to damage. My explainer on how a string trimmer works walks through the head, the line and the drive.

Because you hold the tool out in front of you, your hands carry its weight and its vibration. In a laboratory comparison of grounds equipment, the grass trimmer gave the highest hand vibration, at 3.5 to 5.8 m/s2 with gloves on, against 1.1 to 2.0 m/s2 for a backpack blower (1). That is one reason I like to keep a long edge job short.

A Vertical Blade on a Wheel

A blade edger, often called a stick lawn edger, stands a steel blade on its edge, so it slices down into the turf instead of across it. A wheel rolls along the pavement and a guard covers the blade. According to Ryobi, its 40V brushless edger has a 9 in blade and a cutting depth you set from 1/2 in to 2 in. According to Greenworks, its 60V edger has an 8 in blade that runs at 7,000 rpm with no load and weighs 10.47 lb without the battery.

That is heavy next to a trimmer, but the wheel rides on the pavement, so you steer more than you carry. Greenworks tells owners to hold the rear handle at about hip height and to keep the edger away from the body. On a long concrete edge I find that easier on the arms than a trimmer held out front. If weight matters to you, my list of lightweight string trimmers compares the stated weights.

Using a String Trimmer as an Edger

Many trimmers can edge an existing line, some convert in seconds, and a few makers forbid it. Your own manual decides, so read the edging page before you tilt the head. My comparison of blade edging and string edging sets line, depth and finish side by side for the same border.

Trimmers That Convert to Edge Mode

Two-in-one trimmers turn the head so the line spins on its side. According to Black+Decker, the LST136 needs you to switch off, wait for the head to stop and remove the battery first, then you press the head release button, rotate the head counterclockwise for edging and drop the edge guide until it clicks.

The WORX WG163 turns its telescoping shaft and head 90 degrees and runs on a wheel fitted to the guard; switch off, wait for the head to stop and take out the battery before you turn it. Both guides exist for the same reason: held free-hand, the angle drifts with every wrist movement. When I try a new trimmer on a hard edge, I run a short stretch first and watch where the line lands before I commit to the whole border. My comparison of the WG163 versus WG170 shows which 20V model fits which lawn.

Edge mode has its own rules. Black+Decker says the automatic feed may not work correctly in edge mode without the edge guide, and that line wears faster when it runs over a sidewalk. It also says edging throws stones, metal pieces and other objects at high speed, so people and pets stay at least 100 ft away, and you work going away from walls, steps, stones and trees to limit rebound.

Trimmers That Say No

Not every trimmer allows it. One maker’s manual says the tool is not an edger and warns against tilting it until the line spins near a right angle to the ground. Another says the guard cannot protect against flying debris in that position. A third manual with an edging mode still says not to use the trimmer to create trenches, and rates its results as best on edges already deeper than 2 in.

That last point is the practical limit. A trimmer in edge mode maintains a line that already exists. It is not built to cut a new one, and no setting changes that. Trimmers with a real edge mode or an edger kit are listed in my picks of string trimmers for edging.

What a Blade Edger Does That a Trimmer Cannot

A blade edger earns its place on one job: cutting a vertical face and holding one depth along the whole border.

Depth and a Straight Wall

The depth adjustment on the edger sets how deep the blade cuts. The Ryobi edger has four positions between 1/2 in and 2 in, and its manual says to start at 1/2 in to 1 in, make a shallow test cut, then go deeper progressively. The Greenworks manual says to set the depth so the blade barely touches the ground in your normal working posture. For both makers, you switch off, wait for the blade to stop and take the battery out before you change the setting.

This is the Ryobi procedure for reclaiming a border that has crept over a walk. On a Greenworks or any other edger, set the depth the way that exact model’s manual says:

1. Walk the border and pick up stones, sticks, wire and string, because a blade throws or catches all of them.
2. Put on ANSI Z87.1 eye protection with side shields, hearing protection, heavy long pants, long sleeves, boots and gloves.
3. Switch off, wait until the blade has stopped, remove the battery, set the depth at 1/2 in to 1 in, and fit the battery again once the setting is locked.
4. Cut a shallow test pass along the pavement edge at a steady walking pace. If the blade bogs down, you are going too fast.
5. Switch off, wait until the blade has stopped, remove the battery, and deepen the setting one position, then fit the battery again. Repeat until the face is clean.
6. Rake out the cut turf and sweep the pavement.

Ryobi’s method is a shallow test cut and then progressive deepening, never one deep cut. That control over depth is the part a trimmer cannot copy.

Where a Blade Edger Is the Wrong Tool

Gravel is the first limit. According to Ryobi, the edger is not for use on or near graveled surfaces. That matters on my farm, because the crushed-stone yard has a soft grass edge. I work the grass side of that line with a trimmer, eye protection and the bystander distance the manual gives, and I keep the blade edger for the concrete work pad and the paths to the house.

Wet turf is the second limit. Greenworks says to avoid edging wet soil or wet grass, because the guard clogs and leaves an uneven edge. If it clogs, you switch off, wait for the blade to stop, remove the battery and only then clear the debris. Never stand in line with the blade, and replace a dull blade rather than sharpening it, as Ryobi says. On the Ryobi I set the depth at the shallowest position every time and deepen from there.

Side-by-Side Comparison

Anyone weighing a lawn edger vs string trimmer on paper is choosing between cutting parts, depths and ground types.

Bystander distances and wet-grass rules differ by maker, so read the row that matches the tool in your shed.

Safety Differences You Should Know

Both tools throw debris and keep turning after you release the trigger, so the same kit and switch-off order apply.

Thrown Objects and Your Eyes

Eyes take the worst of it. US emergency departments treated an estimated 81,907 lawn trimmer injuries from 2000 to 2009, and the eye accounted for 42.5% of them, mostly from foreign objects (2). In a Taiwanese series of 26 open-globe eye injuries from lawn trimmers, 57.7% involved a foreign body inside the eye, most often metal (3). Bystanders are hurt too, and older case reports include a person who was standing nearby (4).

None of that research covers blade edgers, so I treat the blade as at least as risky. Ryobi and Greenworks both require ANSI Z87.1 glasses with side shields, and Greenworks adds that everyday glasses are not safety glasses. Both put the bystander line at 50 ft, and Black+Decker puts it at 100 ft for its edge mode. Before my first pass I walk the border and pick up stones, so the guard has less to throw.

Switch-Off Order, Then Noise

Treat the blade and the head the same way. Switch off, wait for the cutter to stop, remove the battery, then touch it. Ryobi warns that a coasting blade keeps spinning after you release the trigger, and it requires the battery out before any adjustment or before clearing a jam. If the edger hits a foreign object, switch off, wait for the blade to stop, remove the battery and inspect the tool before you use it again.

Among string trimmers, the power source changes the noise. NIOSH sampling of landscaping workers found significantly more noise and carbon monoxide exposure with fuel-powered string trimmers than with battery versions (5). I put ear protection on before I start either one, and gas never runs in a shed or garage, even with the door open. My guide to battery and gas string trimmers sets noise, exhaust and upkeep side by side.

Which Tool Fits Your Yard

Pick by the borders you have, not by the tool that sounds more serious. A small lawn with clean edges needs a trimmer. A yard with long hard borders that keep creeping over may justify both tools. An edger and trimmer combo such as the WORX WG163 or the Black+Decker LST136 suits a small lawn whose edges already exist, because line only maintains an edge. My Black+Decker LST136 trimmer review shows how that trimmer edger kit handles a small lawn.

Choose a String Trimmer If

• You cut grass at fences, trunks and beds: only a trimmer reaches those spots.
• Your borders are short and already crisp: a trimmer in edge mode keeps a line that exists, if your manual allows it.
• Your edge runs along gravel: work the grass side with line, eye protection and the maker’s bystander distance, not a blade.

Choose a Blade Edger If

• You have long concrete or paver borders: the wheel and blade hold one depth along the length.
• A border has crept over the pavement: only a blade cuts it back to a clean face.
• You already own a trimmer: the edger then does the one job the trimmer does least well.
• The ground is dry: wet turf clogs the guard.

On my own land the tilled strips under the trees are the exception. Drip lines lie close to the soil there, so I keep the blade edger off those strips and trim them with line, held clear of the lines. The blade edger stays on the paved borders.

Buy the Trimmer First, Add the Edger Later

My routine is simple. Once in spring I redraw the borders along the work pad and the house paths with a blade, starting at the shallowest depth and deepening one position at a time. After that the trimmer keeps the line crisp for the rest of the season, and at the gravel edge I use line only, never without eye protection.

Before you buy anything, open your trimmer manual to its edging page and look at your borders. A short, clean border points to line, and a long hard one that keeps creeping over points to a blade, and that is the whole string trimmer vs edger choice for your yard. When you are ready to buy, my top string trimmers are ranked by yard size, budget and power type.

Frequently Asked Questions

Can a string trimmer be used for edging?

A string trimmer can be used for edging when its manual describes an edging mode, and it works best on a border that already exists. Some makers forbid tilting the head to a right angle, so check yours first.

Is an edger better for edging than a string trimmer?

An edger is better for cutting a clean vertical face and for reclaiming a border that has crept over a walk, because its blade works at a set depth. A trimmer is enough for keeping a crisp border tidy.

Can an edger be used as a trimmer?

An edger cannot replace a trimmer, because makers limit it to edges along walks, drives and beds. Greenworks says its edger is not meant to cut hedges, shrubs, bushes or flowers, and Ryobi says not to use its edger for any other purpose.

Is an edger really necessary?

An edger is necessary only when borders are long and keep creeping over hard surfaces, or when you want a vertical face. A small lawn with short, clean edges can stay with a trimmer.

Do I really need a string trimmer?

A string trimmer is the more useful tool for most yards, because it cuts grass at fences, trunk bases and beds where a mower and an edger do not reach. An edger cannot do that work.

References

1. Oh J, Chen N, Boyd C. Laboratory evaluation of occupational exposure to hand-arm vibration (HAV) during grounds maintenance equipment operations. Ann Agric Environ Med. 2023;30(2):384-389.
2. Leinert J, Griffin R, Blackburn J, McGwin G. The epidemiology of lawn trimmer injuries in the United States: 2000-2009. J Safety Res. 2012;43(2):137-139. doi:10.1016/j.jsr.2012.03.001
3. Zhang JR, Hsieh TC, Chang FL, He MS. Lawn trimmer-related open-globe injuries in Taiwan. Retina. 2022;42(5):973-980. doi:10.1097/IAE.0000000000003402
4. Lubniewski AJ, Olk RJ, Grand MG. Ocular dangers in the garden. A new menace: nylon line lawn trimmers. Ophthalmology. 1988;95(7):906-910. doi:10.1016/s0161-6420(88)33076-9
5. Alexander BM, Graydon PS, Pena M, Feng HA, Beamer BR. Hazardous exposures and engineering controls in the landscaping services industry. Journal of Occupational and Environmental Hygiene. 2025;22(3):189-202.

Safety Note: Read your manual first. A string trimmer or brush cutter throws debris with force, so clear stones, glass and wire from the area before you cut. Wear impact-rated eye protection with side coverage that meets ANSI Z87.1, hearing protection, gloves, heavy long pants, long sleeves and sturdy slip-resistant boots (steel-toe where your manual says so). Keep people and pets at least as far away as your manual says (50 feet in some manuals, 100 feet in others), and stop if anyone comes closer. Keep the correct guard fitted, use only the cutting attachments, handles and harness the maker approves for your exact tool, and never replace trimmer line with wire. A blade can kick sideways when it hits a stump or a thick stem, so fit the handlebar and harness your manual requires for blade work, hold both handles firmly and keep secure footing. Before you clear a jam, clean the tool or change line, a blade or an attachment, switch it off, wait for all movement to stop, then remove the battery, unplug the cord or disconnect the spark plug wire. Refuel a gas model outdoors with the engine off and cool, away from flames or sparks, and move away from the fueling spot before starting, as far as your manual says (often 10 to 30 feet); never run it in a garage, shed or other closed space. For a battery model, use only the maker’s battery and charger, charge it within the temperature range in your manual and never use a damaged or swollen pack. For a corded model, use a GFCI outlet, keep the cord clear of the cutting line and avoid wet conditions.