Lawn Trimmer vs Edger | One Job Each, But Which Do You Need?

String trimmers cut horizontally with a rotating nylon line to trim grass and weeds, while edgers cut vertically with a metal blade to carve a deep, clean border between the lawn and hardscape.

Standing in the power-equipment aisle, the two tools look nearly identical. Both have a long shaft, a small motor, and a spinning head. But swap the cutting head from line to blade and you’ve changed the tool’s entire purpose. Picking the wrong one means either fighting to maintain a crisp edge with a line trimmer or destroying your string in minutes trying to cut tall weeds with an edger. Here’s how to tell them apart and which one your yard actually needs.

What a String Trimmer Actually Does

A string trimmer uses a fast-spinning nylon line to cut horizontally, making it the tool for trimming grass to the same height along fences, around trees, against walls, and under shrubs. The line is flexible, so it bounces off hard surfaces without damaging them. This makes it the general-purpose tool for every mowing finish-up task. Most trimmers handle light brush and tall weeds too, which an edger cannot do safely.

What a Lawn Edger Does

An edger uses a notched metal blade that spins vertically instead of horizontally, cutting a deep slice into the turf along sidewalks, driveways, and flower beds. The vertical blade can cut up to 4.5 inches into the soil, which is what creates that defined, clean separation between grass and pavement. Edgers cannot trim grass height or cut weeds. They are single-purpose tools optimized for one thing: making edges look professional.

Can One Tool Do Both?

Some string trimmers accept an edging attachment that rotates the head 90 degrees so the line cuts vertically. This works for maintaining an existing edge, but it does not match the depth or precision of a bladed edger. The line wears down fast against soil and concrete, and you will not get the deep, crisp cut that a dedicated edger delivers. A trimmer-with-edging-attachment is fine for light maintenance, but if you need to carve a new edge or reclaim an overgrown border, you want a bladed edger.

String Trimmer vs Edger: How They Compare

How to Choose Based on Your Yard

Lawn size is the first filter. If your yard is half an acre or smaller, a 20–40V cordless trimmer handles the trimming job easily. For yards between half an acre and a full acre, step up to a 40–80V cordless or a gas trimmer for the runtime needed. Anything over an acre almost demands a gas trimmer for sustained power. The same sizing principle applies to edgers — a gas edger like the Echo PE-225 is the standard when you have long driveways or extensive border lines to maintain.

If you are already sure you need a dedicated gas-powered tool for heavy edge work, our roundup of the top gas edgers on the market covers the models that deliver the best cut depth and durability for larger lawns.

When You Should Buy Both Tools

Most homeowners with a lawn larger than a quarter acre end up with both. A string trimmer handles the weekly cleanup around obstacles, and a bladed edger delivers the sharp border that makes the yard look finished. If you have to pick one first, buy the string trimmer — it does more jobs, and you can add an edging attachment as a stopgap. But the first time you see the deep, professional edge a bladed edger cuts, you will wonder why you waited.

Common Mistakes to Skip

Using an edger to cut weeds is dangerous — the metal blade grabs and kicks. Using a string trimmer to carve a new edge into soil just wears out the line without getting the depth you need. And buying a 20V trimmer for a one-acre yard means stopping to swap batteries every ten minutes. Match the tool to the task and the size, and you avoid every one of these.

Key Differences at a Glance

Final Decision: Which Tool Goes in Your Shed First?

Start with a string trimmer if you only maintain what already exists — it handles the most jobs around a lawn. Add a bladed edger when you want the crisp, deep edge that makes the whole yard look intentional. For anyone starting from scratch or reclaiming a neglected yard, buy both: the trimmer for the weeds and the edger for the borders. The two tools together cost about the same as a good self-propelled mower, and they are what separates a decent lawn from a great one.