Verdict first: if you mainly edge a lawn and knock down weeds along fences, beds and ditches, a string trimmer is the right tool, and a heavy-duty straight-shaft model running thick line will handle tall grass and tough weeds. If you regularly clear brambles, dense brush, woody weeds or saplings, or you are reclaiming an overgrown lot, you need a true brush cutter: a straight solid driveshaft, a gearbox head, a bike or loop handle with a harness, and a metal blade. Between the two sits the heavy-duty trimmer that accepts a manufacturer-approved blade, which is a good compromise for occasional thick growth, but it is not a substitute for a brush cutter on serious clearing. Here is how to decide.
In this guide
- Side-by-Side Comparison
- What a String Trimmer Does Well
- What Makes a True Brush Cutter Different
- The Middle Ground: Heavy-Duty Trimmers With Blades
- Choosing a Blade
- Decision Factors
- Safety Differences
- How to Clear Overgrowth With a Brush Cutter
- Maintenance Differences
- Which Should You Choose?
- Frequently Asked Questions
Key Takeaways
- String trimmers use nylon line and suit grass, light weeds and edging.
- Brush cutters use metal blades, a gearbox head, a solid driveshaft and a harness for thick brush and small saplings.
- Only fit a blade to a trimmer if the manufacturer approves it and supplies the right guard and handle.
- Never put a blade on a curved-shaft trimmer.
- Blades cut harder and throw debris further, so wear a face shield, eye and hearing protection, long pants and boots.
Side-by-Side Comparison
| Feature | String trimmer | Heavy-duty trimmer with blade | True brush cutter |
|---|---|---|---|
| Cutting head | Nylon line | Line or approved blade | Metal blade; line head optional |
| Shaft | Curved or straight; often flexible cable drive | Straight, sometimes solid drive | Straight, solid steel driveshaft |
| Head | Direct drive | Often gearbox | Gearbox |
| Handle | Loop or D-handle | Loop with barrier bar, or bike handle | Bike handle with barrier bar |
| Harness | Rarely | Shoulder strap | Full double-shoulder harness |
| Typical power | Small gas or battery | Larger gas or high-output battery | Largest gas engines; some high-voltage battery |
| Best for | Lawn edges, grass, light weeds | Tall grass, thick weeds, light brush | Brambles, dense brush, saplings |
| Weight | Lightest | Medium | Heaviest |
What a String Trimmer Does Well
A string trimmer, also called a weed eater or weed wacker, spins nylon line fast enough to cut grass and soft-stemmed weeds. It is the right tool for trimming around trees, fences and beds after mowing, edging along sidewalks and driveways, and keeping a ditch or fence line tidy. Lighter models, both curved-shaft and straight-shaft, are comfortable to use for an hour, and battery versions are quiet and low maintenance. If you are still choosing between types, our guide to types of string trimmers explains the options.
Line has a natural limit. Once stems get thick and woody, line wraps, frays and breaks. Thicker line helps: moving from .065 or .080 inch to .095 or .105 inch line on a trimmer rated for it noticeably improves performance on tough weeds. See what size trimmer line to use for matching line to your machine.
What Makes a True Brush Cutter Different
A brush cutter is built for the torque and shock loads of a metal blade hitting woody stems. The key differences are mechanical:
- Solid steel driveshaft: transmits power without the flex of a cable drive and holds up to blade impacts.
- Gearbox head: angles the blade and multiplies torque, so the blade keeps cutting through thick growth.
- Bike handle and barrier bar: give leverage for sweeping cuts and keep the blade away from your legs.
- Double-shoulder harness: carries the weight on your shoulders and hips so you can swing the head smoothly for long periods.
- Blade guard: larger and stronger than a trimmer guard, designed for metal blades.
Brush cutters also usually have larger engines. That extra power keeps blade speed up in dense growth, which is safer and cleaner cutting than bogging down.
The Middle Ground: Heavy-Duty Trimmers With Blades
Many professional-grade straight-shaft trimmers can be converted to run a grass or weed blade, sometimes marketed as trimmer/brush cutter combos. This works well for tall grass, thick weeds, cattails and light, green brush. Before you do it, check three things in the operator’s manual:
- The model is approved for blade use, and which blades are approved.
- The correct blade guard is installed; trimmer line guards are not designed to contain blade debris.
- A barrier bar or bike handle and a shoulder strap are fitted, as specified.
Never put a blade on a curved-shaft trimmer or any model the manufacturer has not approved. Many battery trimmers are not rated for blades. Our roundup of string trimmer blades covers blade types and compatibility.
Choosing a Blade
| Blade type | Typical teeth | Best for |
|---|---|---|
| Grass or weed blade | 3 or 4 teeth | Tall grass, thick weeds, soft growth |
| Brush blade | 8 or more teeth | Brambles, briars, dense brush |
| Saw or chisel-tooth blade | Many small teeth | Small saplings and woody stems |
| Mulching or knife blade | Varies | Chopping thick vegetation into small pieces |
Saw blades are for brush cutters with full harnesses and bike handles. They can cut small saplings that would otherwise need a chainsaw, but follow the manufacturer’s stated maximum stem diameter. For trees beyond that, use a chainsaw or pole saw.
Decision Factors
What you are cutting
Grass and soft weeds: trimmer. Tall, thick grass and fibrous weeds: heavy-duty trimmer with thick line or an approved grass blade. Blackberry canes, multiflora rose, sumac, saplings and woody weeds: brush cutter.
How much area and how often
A few hundred feet of fence line weekly is trimmer work. Clearing an acre of overgrowth once or twice a year, maintaining a pasture edge or trail system, or cutting firebreaks calls for a brush cutter’s power and harness. For large open overgrown areas, a walk-behind brush mower or a tractor-mounted rotary cutter may be faster still; our guide to brush hog vs finish mower covers that tier.
Power source
Gas still dominates true brush cutters because of power and runtime, but high-voltage battery brush cutters with solid shafts and bike handles are now available from major brands and are much quieter. For lawn trimming, battery models are often the better choice. If you are weighing engine types, see 2-stroke vs 4-stroke trimmers and gas vs battery string trimmers.
Weight and comfort
Brush cutters are heavy, but the harness makes them comfortable for long sessions. A heavy-duty trimmer without a proper harness can be more tiring for big jobs than a brush cutter. If you have back or shoulder issues, a well-fitted harness is worth more than a lighter tool.
Attachment systems
Split-shaft or multi-tool systems let one power head run a trimmer, edger, pole saw and sometimes a brush cutter attachment. They are space-efficient, but brush cutter attachments on these systems usually lack a full bike handle and harness, so treat them as heavy trimmers rather than dedicated brush cutters.
Safety Differences
Blades cut harder and fling debris farther than line, and they can kick sideways, called blade thrust, if they hit a solid stem or object in the wrong part of the blade. Cut with the left side of the blade (about the 8 to 12 o’clock position for most counterclockwise-rotating heads, as the manual shows), keep the harness adjusted so the head floats just above the ground, and keep bystanders at least 50 feet away. Wear a face shield over safety glasses, hearing protection, gloves, long pants or chaps and sturdy boots. Clear the area of rocks, wire and debris before you start, and inspect blades for cracks before every use.
How to Clear Overgrowth With a Brush Cutter
Good technique makes a brush cutter safer and far less tiring. Start by walking the area and flagging stumps, rocks, wire, irrigation heads and anything else the blade could hit. Cut tall growth in two passes: take the top half down first, then cut near the ground, so long stems do not wrap the head or fall back on you. Work with a steady side-to-side sweep from right to left, letting the harness carry the weight and the blade do the cutting, rather than pushing into thick growth. For saplings, approach from the side so the stem meets the cutting zone of the blade, and cut low in one smooth motion. Rake or fork the cut material out of the way as you go so you can see the ground.
Maintenance Differences
- Line heads: refill or replace line, clean grass wrapped under the head, and replace worn eyelets.
- Blades: sharpen with a flat file to the original angle, keep teeth even so the blade stays balanced, and replace any blade that is cracked, bent or missing teeth.
- Gearbox: many brush cutter gearboxes need periodic grease through a fill port; check the manual for the interval and grease type.
- Air filter and spark plug: on gas models, clean the filter after dusty jobs and replace the plug each season.
- Fuel: use fresh fuel mixed at the correct ratio for 2-stroke engines, and run the tank dry or add stabilizer before storage. Our guide on storing a gas trimmer covers end-of-season steps that apply to brush cutters too.
Which Should You Choose?
- If you have a typical suburban lawn: a string trimmer. See our picks for best string trimmers and best cordless string trimmers.
- If you have a larger property with tall grass, ditches and thick weeds: a heavy-duty straight-shaft trimmer with thick line and an approved grass blade.
- If you need to clear brambles, brush or saplings regularly: a dedicated brush cutter with harness and bike handle.
- If you mow rough, open areas of tall grass: consider a wheeled trimmer; see best wheeled string trimmers.
- If you only clear brush once in a while: rent a brush cutter for the day rather than buying one.
For the rest of the yard-care routine, from mowing heights to overseeding, see our lawn care guide.
Frequently Asked Questions
Can I put a blade on my string trimmer?
Only if the manufacturer approves blade use for that model and you install the specified blade, guard and handle. Never fit a blade to a curved-shaft trimmer or a model not rated for it.
What is the difference between a brush cutter and a weed eater?
A weed eater or string trimmer uses nylon line for grass and light weeds. A brush cutter has a solid driveshaft, gearbox head, bike handle, harness and metal blade for thick brush and small saplings.
Can a brush cutter cut small trees?
With a saw or chisel-tooth blade, a brush cutter can cut small saplings up to the diameter the manufacturer states. Larger trees need a chainsaw.
What line size is best for heavy weeds?
Thicker line, such as .095 or .105 inch, handles tough weeds better than .065 or .080 inch, but only use line sizes your trimmer is rated for.
Are battery brush cutters any good?
High-voltage battery brush cutters with solid shafts and bike handles can handle many brush-clearing jobs and are quieter than gas. For all-day clearing, gas models still offer longer runtime.