Wheel Diameter
Affiliate link — we may earn a commissionWheel diameter is the size of the grinding, cutting, or flap disc the tool accepts. The most common size for handheld angle grinders is 4-1/2 inches (115 mm). Larger grinders accept 5-inch, 6-inch, 7-inch, or 9-inch wheels. A 4-1/2-inch grinder handles metal cutting, weld grinding, rust removal, and light concrete work. It cuts steel up to about 1-1/2 inches thick in a single pass. A 7 or 9-inch grinder handles large concrete cuts, heavy structural steel, and industrial grinding. Bigger wheels also spin at lower RPM for safety.
Why It Matters
The wheel size limits your cut depth and grinding coverage per pass. A 4-1/2-inch grinder covers 90% of what most people need. If you're cutting rebar, heavy pipe, or concrete, step up to a 7-inch. Don't put a larger wheel on a smaller grinder. The tool can't handle the forces.