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If you need to grind welds, cut steel, strip rust, or polish a surface, an angle grinder is the tool. We compare models from DeWalt, Milwaukee, Makita, Bosch, Ryobi, and Craftsman using manufacturer data sheets and aggregated user reviews. Need a compact 4.5-inch for detail work? A balanced 5-inch for general tasks? A 7-inch that won't quit on sustained grinding? We break down disc size, power source, and features so you can pick the right one.
An angle grinder is a handheld power tool with a rotating abrasive disc set at 90 degrees to the motor. Disc diameter runs 4.5, 5, 7, or 9 inches, and it determines your cutting speed and the jobs the tool can handle. The 4.5-inch is portable and built for detail work. A 5-inch adds reach while staying manageable. The 7-inch is the industry standard for metalworking. And a 9-inch handles sustained grinding on thick material and concrete.
You'll find two main types: corded (120V/240V AC) and cordless (18V/20V Li-ion). Corded models deliver constant power at consistent RPM. Cordless models trade runtime for portability, giving you 15-45 minutes per battery. The discs are swappable: grinding discs remove material gradually, cutting discs slice through metal faster, and flap discs polish and finish surfaces.
Features to pay attention to: kickback brake (stops the disc in 2-3 seconds if it binds), RPM rating (higher for small discs, lower for large), variable speed (lets you match RPM to your material), and switch type (paddle vs. slide). Weight, vibration control, and dust collection vary by model. Serious users tend to own at least two, one set up for cutting and one for grinding.
For detailed reviews of the best angle grinders, including specs, prices, and pros/cons, see our best angle grinders guide.
A 4.5-inch disc is compact, light, and built for detail work and cutouts. The 5-inch gives you slightly more reach and cutting speed while staying portable. A 7-inch covers grinding, cutting, and polishing in one tool, which is why it's the shop standard. The 9-inch handles sustained grinding on thick material and concrete. For residential and DIY work, 4.5 to 5-inch is the default. In professional metal shops, 7-inch dominates.
Smaller discs (4.5-inch) run 10,000-13,000 RPM to maintain cutting speed. Larger discs (7-inch) run 6,000-9,000 RPM to prevent binding and vibration. Variable-speed grinders let you drop RPM for heat-sensitive materials like aluminum and copper, or push it higher for steel and cast iron. Higher RPM means faster material removal but also more heat and sparks. Match your RPM to the disc size and material you're working.
Corded (120V/240V) grinders deliver constant power at stable RPM under load. Cordless (18V/20V Li-ion) give you portability and quick setup. Runtime depends on disc size: 4.5-inch grinders get 20-45 minutes per battery, while 5-7 inch grinders get 15-30 minutes. Go corded for all-day grinding. Go cordless if you're bouncing between locations or working in spots without power.
An electric brake stops the disc within 2-3 seconds if it suddenly binds or catches. This prevents violent wrist rotation and hand injuries. Professional-grade grinders include them as standard. Budget models sometimes skip them. Check the spec sheet before buying. A grinder without a kickback brake is riskier, especially for cutting where binding happens more often.
4.5-inch cordless grinders weigh 3-5 lbs. 5-inch models run 4-6 lbs. 7-inch corded grinders land at 7-10 lbs. Lighter is easier to control and less tiring for overhead work. Heavier gives you stability for sustained grinding and dampens vibration. Some people prefer lighter for precision; others like the heft for power delivery. Try holding one before you commit if the store lets you.
A paddle switch on the side gives you instant on/off with your fingers while gripping the tool. A slide switch on the handle is safe too, just slower to toggle. Pros prefer paddle switches on kickback-equipped models. Either one works for occasional DIY use. If you can, test both at a store. Comfort matters when you're running the tool for extended stretches.
Angle grinders come in 4.5-inch, 5-inch, 7-inch, and 9-inch sizes. The 4.5-inch is compact and portable, built for detail work and tight spots. A 5-inch gives you a bit more reach without getting unwieldy. The 7-inch is the standard for general grinding, cutting, and polishing. And a 9-inch is heavy-duty, built for sustained metal grinding and concrete work. If you're doing DIY or residential projects, go with a 4.5 or 5-inch. Professionals lean toward 7-inch for the range it covers.
A kickback brake (also called an electric brake) stops the disc within 2-3 seconds if it suddenly binds or catches. It prevents violent wrist rotation and hand injuries from uncontrolled spin-down. Professional-grade grinders include kickback brakes as standard. Budget models sometimes skip them. If you're grinding metal or cutting, you want one. Wear safety gloves and a face shield either way.
4.5-inch to 5-inch grinders run 10,000-13,000 RPM at no-load. 7-inch models run 6,000-9,000 RPM. Higher RPM means faster grinding and cutting, but it also means more heat and vibration. Disc size and task dictate the right speed: thin discs need higher RPM, while thick discs run lower to prevent binding. Variable-speed grinders let you dial in the right RPM for your material and disc, which is worth paying for if you work with different metals.
Corded angle grinders (120V/240V) deliver constant power, never lose speed under load, and cost less ($50-$150). Cordless models (18V-20V Li-ion) give you portability and no cord management, which matters on job sites and in tight spaces. Expect 15-45 minutes per battery on a 4.5-inch cordless grinder. Pick corded for heavy sustained work. Pick cordless if you move between locations a lot or hate extension cords.
Angle grinders handle both well. A grinding disc removes rust, welds, and sharp edges. A cutting disc (thinner, reinforced) slices through steel, rebar, and pipes. Keep a few of each on hand if you do mixed work. A variable-speed model with decent power covers the widest range. Worth noting: angle grinders are slower than band saws for metal cutting, but they're faster to grab and more portable for field work.
You need safety glasses or a face shield because debris flies hard. Cut-resistant gloves protect against hot material and the spinning disc. Closed-toe shoes are non-negotiable since metal chips burn. Hearing protection is smart too; grinders run 90+ dB, which adds up fast. An apron or heavy clothing reduces spark burns. Never wear loose clothing, ties, or dangling sleeves that could catch the disc, and keep long hair tied back.
A paddle switch sits on the side or handle and lets you cut power instantly with your fingers while gripping the tool. A slide switch on the handle is safe too, just a bit slower to toggle. Pros prefer paddle switches on kickback-protected models because you can shut off the grinder the instant it binds. Slide switches are fine for occasional use. It comes down to feel, but paddle is becoming the industry default.