What Cutting Width Do I Need on a String Trimmer? A Yard-by-Yard Guide

A string trimmer cutting width of 11 to 13 inches suits a small yard and tight beds, 14 to 16 inches suits most lots, and 17 to 20 inches suits long runs of open ground. That is my rule, built on the swath figures makers publish for the trimmers they sell. On my own land I match the width to the strips I trim, the tree rows, the fence line and the gravel edge, because a wider circle costs run time on a battery tool and demands a shorter leash on the line. Below you get the numbers behind each size, a worked example, the limit on how long your line may grow, and the safety rules that stay the same at any width.

What Cutting Width Do I Need on a String Trimmer? The Short Answer

Pick the width from the size of the ground you trim, then check what the extra inches cost. The table below sets each size against the ground it suits. Most battery trimmers sit in the middle row, and makers sell the widest sizes mostly as gas straight-shaft trimmers, while my guide to straight and curved shaft trimmers explains the separate shaft choice.

The rest of this guide explains each row, so you can test my rule against your own ground.

What Cutting Width Means on a String Trimmer

Cutting width is the diameter of the circle the line draws as the head spins. Makers print it as cutting swath, cutting path, cutting width or cutting diameter, and all four mean the same circle. Each figure belongs to a line at its proper length, so the number is a limit, not a promise that your line stays that long.

Where the Swath Comes From

The string trimmer cutting swath comes from a small steel blade on the guard, which trims the line whenever it grows past the blade. Where that blade sits sets the swath. According to Greenworks, its Pro 60V ST60L254 ships at 14 inches, and turning the blade 180 degrees gives 16 inches. I explain how the drive turns the head and cutting line in my guide to how a string trimmer works.

Milwaukee’s M18 trimmer 2828-21 uses the same blade turn for 14 or 16 inches. On the DeWalt DCST972 you move the blade to the other slot for 15 or 17 inches, and Craftsman’s CMCST930 has two guard positions for 11 or 13 inches.

Fixed and Adjustable Swaths

Other trimmers hold one width. The Greenworks 40V 12 inch model is fixed at 12 inches, the EGO ST1511T lists a 15 inch swath and the EGO ST1623T a 16 inch swath. Take the figure from the manual for your exact model, not from a store field. One store listing gave 14 inches for EGO’s ST1502SA, while EGO’s manual says 15. I cover the 16 inch EGO model in full in my review of the EGO ST1623T.

How Cutting Width Changes the Work

Width changes two things you feel: how many walks a job takes and, on a battery tool, how long the pack lasts. At either width EGO approves, you cut with the tip of the line, as its manual puts it.

A Worked Example With Walks

Take a bank 72 inches wide, and say each walk along it clears one swath width with no overlap. A 12 inch swath needs 6 walks. A 16 inch swath needs 5, because 72 divided by 16 is 4.5. A 20 inch swath needs 4.

Real passes overlap, and the true counts depend on how much, so the one-walk saving holds only for the no-overlap case. In that example, going from 12 to 16 inches saves one walk in six. I care about that on a long fence line, and I do not care about it around the steps of the house. My sizing guide covers the string trimmer size you need once the swath is settled.

What a Wider Swath Costs on a Battery Trimmer

Greenworks states the trade in the ST60L254 manual: use 14 inches for greater runtime and 16 inches for a larger cutting area. Milwaukee gives numbers for its M18 trimmer with the XC6.0 pack, and they show the same trade.

On this Milwaukee, the 16 inch swath is about 14 percent wider and gives up about 10 percent of run time on low and about 14 percent on high. As a simplified calculation, with the same walking pace and the same growth, that works out to about the same area per charge. For this model the wider swath buys fewer walks. I put that Milwaukee head to head with a 20V rival in my WORX WG170 against Milwaukee 2828-21 comparison.

Run times do not carry across brands, because the packs and the test conditions differ. Craftsman’s 75 minute figure for the CMCST930 with the 5.0 Ah pack is for the 11 inch swath, low speed and no load, so a real 13 inch job on high speed will fall short of it. I treat every run time as a ceiling and plan my edging against the strip, not against the box.

Match the Width to Your Yard

Three sizes cover nearly every trimmer on the market, and each one has a job it does best. The examples below use the maker’s own swath figure for each model.

Small Yards and Bed Edges at 11 to 13 Inches

Narrow swaths come on light tools. According to WORX, the WG163 weighs about 5.3 lb with its battery, and Craftsman’s CMCST930 drops to an 11 inch setting for the tightest beds. Along beds and paths at the house, a narrow circle is easier to place, and I take the extra walk instead of clipping a bed edge with a wide swing. I set the WG163 against its sibling in my WORX WG163 and WG170 comparison.

Most Lots at 14 to 16 Inches

This is where battery trimmers cluster, and the adjustable ones above let you pick 14 or 16. If you do not know your yard yet, a 16 inch trimmer that also offers 14 gives you both choices, and that is the kind I recommend. When I weigh any trimmer, I look at its swath first, because the swath sets how I plan the strip.

On the tree-row edge I set the swath against the width of the tilled strip, and I keep the head well away from the trunks. EGO warns that the line damages tree bark, and Husqvarna says the same about sensitive bark. A 16 inch swath reaches 8 inches out from the centre of the head, so the line gets that close to a trunk or a drip line.

Fence Lines and Open Ground at 17 to 20 Inches

Gas straight shafts own this size. The Echo SRM-3020T pairs its 20 inch swath with a 30.5 cc engine and a 0.71 L tank, and Echo lists it at 12.3 lb dry without the cutter head. The 130L runs a 28 cc engine and a 0.5 L tank, and Husqvarna’s manual gives 11.0 lb without fuel, cutting attachment and guard. The two weights leave out different parts, so do not compare them. I set these two gas models head to head in Husqvarna 130L against Echo SRM-3020T.

On battery, the DeWalt DCST972 reaches 17 inches when you move its blade to the second slot, which suits long runs without fuel. Gas tools add a fuel routine and more noise, both covered in the safety section. Echo and Husqvarna both give a 50:1 mix for these models, so follow the ratio in your own manual.

Do Not Stretch the Line Past the Swath

Line longer than the maker’s swath loads the motor. DeWalt’s manual says line past the 15 inch swath of the DCST970 harms performance, run time and motor life, and may void the warranty. Echo’s gas manual says a trimmer run without its cut-off knife gets line that is too long, and the engine will overheat. My guide on picking the trimmer line size to use starts from the same manual check.

How Long the Line Should Stick Out

After loading, the manuals ask for equal lengths on both sides: about 5 inches for the Greenworks Pro 60V, the Husqvarna 130L, the Echo SRM-3020T and DeWalt’s string trimmer attachment, and 5.5 inches for EGO’s POWERLOAD ST1521S. The blade on the guard then trims the line back to the swath as it feeds. I never pull line out past that blade to gain a wider circle.

The Vibration Side of Line Length

On one gas test machine, researchers varied line length, engine speed and handle material, and all three changed hand vibration. The lowest reading, 2.76 m/s2, came with a 100 mm line, about 3000 rpm and a plastic handle (1). That is one machine, so I read it as one more reason to keep the line at the maker’s length, not as a length to copy.

Safety Rules That Do Not Change With Width

Width changes how much ground the line sweeps. It does not change what the line throws, and a wider circle puts more line in motion at once.

Eyes, Hearing and Bystanders

Eye injuries lead the numbers. US emergency departments treated an estimated 81,907 lawn trimmer injuries from 2000 to 2009, the eye accounted for 42.5 percent of them, and most came from foreign objects (2). Case reports describe injuries to bystanders as well as operators (3). Wear eye protection marked ANSI Z87.1, as the EGO, Milwaukee and Greenworks manuals require, along with hearing protection, heavy long pants, long sleeves, sturdy slip-resistant boots and gloves.

• Bystanders: Milwaukee and Greenworks say 50 feet, and DeWalt, Craftsman and EGO’s ST1521S manual say 100 feet. Follow the distance in your own manual, and stop the trimmer when someone comes closer.
• The guard: it stays on at every width. Never run a trimmer without it.
• Blades: use only a blade the maker lists for that exact tool, with the blade guard, the handle with barrier bar and the harness its manual requires, and keep the harness worn and fastened whenever a blade is fitted. Nylon line is the default.
• Debris: clear stones, glass and wire before you start.

Vibration and noise follow the tool more than the swath. In a laboratory test, a grass trimmer gave 3.5 to 5.8 m/s2 at the gloved hand, the highest of the grounds equipment tested (4). Two petrol grass-trimmer engines measured about 100 and 105 dB(A) at the operator (5). NIOSH sampling of landscaping workers found significantly more noise and carbon monoxide with fuel-powered string trimmers than with battery versions (6).

Gas Trimmers at Any Width

Refuel outdoors with the engine off and cool, away from flames, and move away from the fuel spot before you start. A gas trimmer never runs in a shed or garage, even with the door open. Mix regular gasoline with two-stroke oil at 50:1, or at the ratio and oil grade your manual names. My list of the best gas trimmers shows the weight and warranty of each gas model.

Pick the Width for the Strip You Trim Most

Three checks before you buy. Read the maker’s figure for your exact model. Know that a wider swath shortens run time on a battery tool. Keep the line at the length the cut-off blade sets.

Before a long edge I walk the strip once with nothing in my hands, count the walks a swath would need, and decide whether a wider one saves enough to matter. Choose the string trimmer cutting width that fits the strips you trim most, and confirm the maker’s figure for that exact model. My ranking of the best overall string trimmers shows the swath of each pick for every yard.

Frequently Asked Questions

How long should trimmer line be sticking out?

Trimmer line should stick out about 5 inches on each side right after you load the head, according to the manuals for the Greenworks Pro 60V, the Husqvarna 130L and the Echo SRM-3020T, and EGO shows 5.5 inches on its POWERLOAD head. From there the blade on the guard keeps the line at the maker’s swath. Line longer than that swath loads the motor.

How to get more string out of a trimmer?

To get more string out of a trimmer, use the feed method your head has: on a bump head, tap it on bare ground while it runs at normal speed, and on an automatic head let it feed itself, since Greenworks says bumping its 40V model will damage the trimmer. If the line is too short to feed, switch off, wait for the head to stop and take out the battery, or pull the spark plug wire on a gas model, or unplug a corded one. Then pull the line out by hand as your manual shows.

What are the common cutting swath widths for string trimmers?

The common cutting swath widths for string trimmers run from 11 to 20 inches. Small battery and corded models cut 11 to 13 inches, most battery trimmers cut 14 to 16, and gas straight shafts reach 17 to 20 inches. Your manual gives the exact figure for your model.

What is the cutting swath width of an electric string trimmer?

The cutting swath width of an electric string trimmer runs from 11 to 17 inches among the models in this guide. The Craftsman CMCST930 offers 11 or 13, the WORX WG163 and the Craftsman CMEST900 cut 12 inches, the DeWalt DCST970 cuts 15, the EGO ST1623T cuts 16, and the DeWalt DCST972 reaches 17 with its blade in the second slot. Your manual gives the figure for your exact model.

What is the cutting swath width of a Husqvarna string trimmer?

The cutting swath width of a Husqvarna string trimmer is 18 inches on the 130L, and 17 inches on the 122LK and on the 122RJ with its string head, according to Husqvarna. The cut-off blade on the guard holds the line to that width. Check the manual for your model before you trim.

References

1. Mallick Z. Optimization of the operating parameters of a grass trimming machine. Appl Ergon. 2010;41(2):260-265. doi:10.1016/j.apergo.2009.07.010
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. 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
4. 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.
5. Mallick Z, Badruddin IA, Khaleed Hussain MT, Salman Ahmed NJ, Kanesan J. Noise characteristics of grass-trimming machine engines and their effect on operators. Noise Health. 2009;11(43):98-102. doi:10.4103/1463-1741.50694
6. 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.