Key Features
Compact PowerThe brushless motor delivers 755 MWO and 12,500 no-load RPM, so this 4-inch angle grinder has the output for demanding grinding and cutoff work without dragging an air hose around. More ControlThe anti-rotation system and electronic brake are there for the moments that matter. If the wheel pinches, stalls, or binds, the tool reacts fast to help cut down reaction torque and stop the wheel quickly. Tight-Space DesignThe slim ergonomic body is built for access where larger grinders get awkward. That matters when you are working inside steel framing, around equipment, or anywhere clearance is limited.
Overview
The DeWALT DCG400B ATOMIC 20V MAX 4-in. Angle Grinder, Tool Only is a compact cordless grinder built for high-power cutting and grinding where a full-size tool or air setup gets in the way. This is a cordless angle grinder designed for metal cutting, grinding, and tight-space fabrication work. Model Number: DCG400B. If you want pneumatic-like performance without the hose, this is the point of this tool.
What makes this grinder matter on the job is the combination of size and output. DEWALT rates it at 755 MWO with a 12,500 RPM no-load speed, which gives it the kind of fast wheel speed you want for cutoff wheels and light grinding. That means quicker cuts, less waiting on the wheel, and a tool that feels ready the second you lean into the work instead of feeling like a compromise just because it runs on a battery.
The compact ATOMIC layout is the real selling point. DEWALT built this 4-inch angle grinder to work in ultra-tight areas, and the slim body plus paddle switch format help it fit where larger grinders start fighting you. If you do metal framing, fab work, mechanical repair, punch-list cutting, or field modifications, that smaller footprint is not a minor detail. It is the difference between getting the cut done cleanly and wasting time changing your angle or reaching for another tool.
Control features are strong here, and on a grinder that matters more than on most tools. The DEWALT anti-rotation system is designed to sense a pinch, stall, or bind-up event and stop the wheel quickly to reduce reactionary torque. On top of that, the electronic brake is designed to stop the wheel within 1.15 seconds after the trigger is released. In real use, that means less waiting for the wheel to coast down and better control when you are repositioning between cuts.
DEWALT also made the tool easier to live with day to day. The spindle lock speeds up wheel swaps without needing multiple wrenches, and the clip-on guard setup lets you quickly convert the included Type B guard into a Type A guard. The forward exhaust system helps direct air away from the user while helping the motor manage heat. These are the kinds of details that do not sound flashy, but they save aggravation when the tool is being used all day.
On compatibility, the DCG400B runs on the DEWALT 20V MAX platform and is sold as a tool only, so battery and charger are separate. It is compatible with standard 4-inch accessories using 3/8-inch and 5/8-inch arbor sizes, which matters because it keeps you in common wheel sizes instead of locking you into something odd. It is also listed as TOOL CONNECT Chip Ready, so users already working inside that DEWALT system can add tracking capability with the chip sold separately.
Who should buy it? Contractors, metalworkers, maintenance crews, remodelers, and serious DIY users who need a cordless cutoff and grinding tool that works in places a larger grinder will not. If you mostly work on open benches with plenty of room, a bigger grinder may still make sense. But if access is tight and mobility matters, the DeWALT DCG400B ATOMIC 20V MAX 4-in. Angle Grinder, Tool Only is the kind of compact grinder that earns its keep fast.
Cut and Grind in Tight Spaces
This grinder is built for the jobs where space is the real problem. The compact body and cordless design make it easier to get the wheel where you need it without wrestling a hose or oversized housing.
- Slim ergonomic design for access into ultra-tight spaces
- 13% lighter than a competitive pneumatic angle grinder in use, according to DEWALT
- Paddle switch with lock-off and no-lock-on design for controlled operation
Built for Fast, Controlled Operation
The control package here is stronger than what you usually get on a compact grinder. DEWALT focused on reducing downtime between cuts and helping the tool react when the wheel gets into trouble.
- Electronic brake designed to stop the wheel within 1.15 seconds after trigger release
- Anti-rotation system helps reduce reactionary torque during pinch, stall, or bind-up events
- Clip-on guard setup allows quick guard changes between applications
Compact Tool, Serious Output
Small only helps if the grinder still has the speed to do the work. This one does. The brushless motor gives it the wheel speed and output needed for cutoff work and light grinding without feeling underpowered.
- Brushless motor rated at 755 MWO
- 12,500 RPM no-load speed for aggressive cutting and grinding
- Forward exhaust system helps direct air away from the user and manage motor heat
What’s in the Box
- (1) DCG400 ATOMIC 20V MAX 4 in. Angle Grinder
- (1) Wrench
- (1) Type B Guard with Type A Clip-on Guard
- (1) 1/16 in. Type 1 Wheel
- (1) 1/8 in. Type 1 Wheel
Battery and charger are sold separately.
At a Glance
12,500No-Load RPM755MWO4 in.Wheel Size4.34 lbsTool Weight
Key Specifications
| Voltage (V) | 20 V |
|---|---|
| No-Load Speed (RPM) | 12,500 RPM |
| Power Output | 755 MWO |
| Wheel Diameter | 4 in. |
| Arbor Sizes | 3/8 in. and 5/8 in. |
| Power Source | Battery |
| Weight (lbs) | 4.34 lbs |
| Tool Only | Yes |
Compatibility
Battery Platform Part of the DEWALT 20V MAX system. Battery and charger are sold separately. Accessory Fit Compatible with standard 4 in. accessories using 3/8 in. and 5/8 in. arbor sizes. Tool Tracking TOOL CONNECT Chip Ready. The chip is sold separately for jobsite asset management and tool location features.
Built For
MetalworkingFabricationConstructionGeneral ContractingMaintenanceRemodelingCutoff WorkGrinding in Tight Spaces
Pro Tip
Use the included 1/16 in. Type 1 wheel when you want faster cutoff speed, and switch to the 1/8 in. wheel when you need a little more wheel life. On a compact grinder like this, matching the wheel to the job makes a noticeable difference.
Warranty & Support
3 Year Limited Warranty, 1 Year Free Service, 90 Day Satisfaction Guaranteed.
Tool Nut’s Take
Tool Nut’s Take
DeWALT DCG400B ATOMIC 20V MAX 4-in. Angle Grinder, Tool Only is the right call when access matters as much as power
This is a smart grinder for guys who are tired of choosing between a bulky cordless model and an air tool tied to a hose.
- Who it’s for: Pros and serious DIY users doing metal cutting, fabrication, repair, and field work in cramped areas.
- Why it stands out: You get real speed at 12,500 RPM, strong control features, and a compact body that is actually useful in places larger grinders struggle.
- Worth knowing: It is sold as a bare tool, so plan on a 20V MAX battery and charger if you are not already on the platform.
Common Questions
- Is this a cordless or corded angle grinder? It is a cordless angle grinder powered by a DEWALT 20V MAX battery.
- Does it come with a battery and charger? No. The DCG400B is a tool-only version.
- What accessory sizes does it accept? It is compatible with standard 4 in. accessories using 3/8 in. and 5/8 in. arbor sizes.
- Does it have a brake? Yes. It features an electronic brake designed to stop the wheel within 1.15 seconds after the trigger is released.
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