Buying guide
String Trimmer Buying Guide
How to choose a battery string trimmer: voltage platforms, line systems, swath width, and the decision framework.
Voltage platform: the battery decision comes first
Battery trimmers are sold into platforms: 20V (DeWalt, Worx), 40V (Black+Decker), 56V (EGO). Higher voltage generally means more torque at the head. But the platform decision is also economic: if you already own batteries for a platform, the bare-tool price of a compatible trimmer is far lower than a kit. Check your garage before you check the specs.
Line system: bump, button, or automatic
Bump feed (DeWalt DCST922B) advances line when you tap the head on the ground: cheap and reliable, but it interrupts the cut. Button feed (Worx Command Feed) advances line on demand. Automatic systems (EGO Powerload plus Line IQ) wind and feed line without your involvement. Automatic is the best experience; bump feed is the cheapest to manufacture.
Swath and line diameter
Swath (12 to 15 inches here) determines passes per session; line diameter (0.065 to 0.095 inch) determines what you can cut. Match both to your vegetation: lawn grass only needs 12 inches and thin line, while weeds need 13-plus inches and 0.080-inch line or thicker.
Decision framework: buy this type if, avoid if
Buy a 56V-class trimmer (EGO) if your yard is a quarter acre or larger, you cut weeds regularly, or you hate line maintenance. Avoid it if your yard is small or you already own another battery platform. Buy a 20V-class trimmer (DeWalt, Worx) if you own the batteries, your yard is small, or budget rules. Avoid 20V if you fight thick weeds weekly. Buy 40V (Black+Decker) if you want the middle ground: more torque than 20V without the 56V price.
Questions, answered
How long does a battery last while trimming?
Runtime depends on battery amp-hours and how hard you push the tool. As a rule of thumb, a 4.0 to 5.0Ah battery handles a typical suburban yard on one charge; thick weeds drain it faster. Two batteries cover large properties.
What line diameter should I buy?
Match the line your trimmer's head is designed for: 0.065 inch for the Worx, 0.080 for DeWalt and Black+Decker, 0.095 for the EGO. Using line thicker than the head rating strains the motor.
Do I need a shoulder strap?
For trimmers over about 9 pounds with battery, yes for sessions longer than 20 minutes. The EGO ships with one; lighter 20V models are usually fine without.
Can I use a trimmer as my only yard tool?
For the lawn edges, fence lines, and around obstacles, yes. But a trimmer does not replace a mower for open grass or a blower for cleanup; it is a complement, not a substitute.