Best 6-Inch Angle Grinders: Corded Power vs Cordless Convenience

Introduction

Six-inch grinders occupy a useful middle ground: more disc real estate and material removal than a typical 4-1/2 to 5-inch tool, without stepping up to the genuinely unwieldy 9-inch class. To find out where the value sits today, four large grinders went head to head: a top-tier corded Metabo as the benchmark, plus three cordless contenders from Bosch, Milwaukee, and DeWalt. Each was measured on real power output under load, speed, runtime, vibration, weight, and kit price.

How They Were Evaluated

Power was measured on a dynamometer that tracks RPM and output under progressively heavier grinding loads, starting at a light-to-normal grinding task and building up to a full stall-level push. Runtime was tested with an equivalent 8.0Ah (roughly 144Wh) battery on each cordless tool under the same moderate grinding load, so efficiency is compared fairly rather than inflated by bigger packs. Vibration was measured with both grinding and cutting discs, and every kit was weighed and priced as tested.

One thing worth flagging early: even the best cordless tools were pushed to their limits trying to match what a 14.5-amp corded grinder pulls from a standard wall outlet, so the comparison is closer than you might expect, but not in every category.

The Corded Benchmark: Metabo

The Metabo is their highest-rated 14.5-amp, 6-inch corded model, and on the dyno it was simply a monster. Under a 300W-equivalent load it held 8,560 RPM, and it kept pulling until the load rig reached a channel-record 1,010W output, roughly 1,310W coming out of the grinder itself. When pushed hard, it drew up to about 2,100W and 20 amps from the wall, which is effectively the ceiling of a standard US outlet.

It is also genuinely smooth. Vibration measured just 9 m/s² with a 5-inch grinding wheel and only 7 m/s² with a 6-inch disc, impressive for an AC tool. As a corded model it does not score on battery runtime, and its $290 price as tested puts it right up against the cordless kits. It is the tool to beat if you have power always available.

Bosch ProFactor GWS 18V-13 CN

The Bosch ProFactor GWS 18V-13 CN is the step up to 6 inches in Bosch’s ProFactor line in the US, and the cheapest way to buy it as a kit with the ProFactor 8.0Ah battery came to $320, purchased piece by piece. The complete package weighs 7 lb 2 oz, heavier than the corded Metabo but far from the heaviest here.

Despite an 8,500 RPM rating on the label, free speed measured closer to 7,000 RPM and dropped to about 6,360 RPM under load, suggesting extra gear reduction for grunt when pushed. On the dyno with the 8.0Ah ProFactor battery it managed 760W, quite strong, though some lighter 4-1/2 inch grinders have produced more. With a 4.0Ah battery that figure falls to 560W.

Where the Bosch shines is comfort and efficiency. Vibration measured just 5 m/s² with a grinding wheel and 6 m/s² with a cutting disc, the lowest here alongside its smooth feel, and in the runtime test it lasted a full 19 minutes on an equivalent battery, longer than almost anything previously tested at that load. If you value efficiency and a pleasant tool to hold over raw peak power, this is a strong pick.

Milwaukee M18 2980

The Milwaukee M18 2980 is rated at 9,000 RPM and, kitted with an XC 6.0 battery, came to $335 as tested. Milwaukee’s newer Forge battery swaps into that price equation, adding a bit of cost but improving both weight and performance, and it scores best with the Forge pack fitted.

Under load it spun the dyno at about 7,960 RPM, well above the Bosch, and it put out up to 960W with the XC 6.0, dipping slightly to 900W with the XC 8.0 due to cell differences. With the Forge battery it climbed to 8,230 RPM under load and, when pushed to the limit, crested 1,150W, surpassing even the corded Metabo drawing 2,000W from the wall. That is the high-water mark for 18V-class performance here.

The trade-offs show up in runtime and vibration. On an equivalent battery it ran about 13.5 minutes, and it measured 12.32 m/s² of vibration, similar to its own 4-1/2 inch sibling. Compared against Milwaukee’s ~670W 4-1/2 to 5-inch model, though, this 6-inch package is a dramatic improvement and earns a clear thumbs-up.

DeWalt FlexVolt DCG418

The DeWalt FlexVolt DCG418 is a 60V FlexVolt tool with proportions that put all the mass up front around the motor, and it is the most powerful grinder measured here. It barely drops RPM under load, holding 8,380 RPM at the first load stage and refusing to fall further even as another 100 to 200W was stacked on. It maxed out a three-load test rig and required a fourth stage, ultimately producing 1,270W. After extended use, the takeaway is simple: you would have to do something very aggressive to slow this tool down.

It also came in as the cheapest kit on the day at $290, including a 9.0Ah FlexVolt battery, which is arguably the brand’s best-performing pack. Runtime was the shortest of the three cordless tools at 11.5 minutes standardized, and it is programmed for constant speed regardless of battery voltage. Vibration with a grinding disc was a buttery 4 m/s², but with a 6-inch cutting disc the free-spinning head developed a noticeable wobble and higher vibration, which disappeared once the disc was actually cutting, and the included handle is the most basic of the group, with no vibration damper. As tested, it scored 234.0 against the Metabo’s 222.0, the Bosch’s 168.0, and the M18’s 182.5.

Buying Advice

If you always have an outlet nearby, the corded Metabo is the outright power and smoothness benchmark, and it makes the strongest argument that corded is still the reference point in this size class. Among cordless options, the DeWalt FlexVolt DCG418 is the value and power leader: lowest kit price, the brand’s best battery included, and the highest measured output, provided you accept its shorter runtime and fussier behavior with free-spinning cutting discs. The Milwaukee M18 2980 is the balanced performer, especially with a Forge battery, while the Bosch ProFactor is the efficiency and comfort pick, offering the longest equivalent runtime and the lowest vibration. Note also that a recent DeWalt corded 6-inch model bought for comparison failed within a day of testing and produced significantly less power, so DeWalt’s strength here is clearly in the FlexVolt platform.

Conclusion

In this 6-inch class there is no single winner for everyone. The Metabo proves corded still sets the power and smoothness bar, the DeWalt FlexVolt delivers the most measured power at the lowest kit price, the Milwaukee offers the best all-round cordless package, and the Bosch rewards efficiency-focused buyers with unmatched runtime per charge and the gentlest handling. Match the tool to how you actually grind, and each of these earns its place.