Key Features

Compact PowerThe DeWALT DCG402B 20V MAX ATOMIC 4.5-in. Angle Grinder puts up to 760 MWO and 11,000 RPM in a smaller body, so you can grind and cut in tight spots without giving up real jobsite performance. More ControlThe ANTI-ROTATION system and electronic brake are there for the moments that matter. If the wheel binds, the tool reacts faster to help reduce kickback and bring the wheel to a stop quickly after trigger release. Faster SetupQuick guard conversion, a spindle lock for wheel swaps, and a slim grip help you spend less time fiddling with the tool and more time cutting, grinding, and cleaning up metal.

Overview

The DeWALT DCG402B 20V MAX ATOMIC 4.5-in. Angle Grinder is a cordless 4-1/2 inch angle grinder built for metal cutting, grinding, and cleanup work where size matters just as much as output. This is an angle grinder designed for tight-space metalworking and general jobsite grinding. Model Number: DCG402B. Sold as a tool-only configuration, it is aimed at users already on the DeWALT 20V MAX battery platform who want a more compact grinder without stepping down to a light-duty tool.

On the numbers that matter, this grinder delivers up to 760 MWO and 11,000 RPM no-load speed from a brushless motor. That matters because a compact grinder only earns its keep if it can still remove material quickly, cut cleanly, and keep pace on steel fabrication, pipe work, weld cleanup, and general punch-list grinding. The brushless setup also helps with efficiency and runtime compared to brushed designs, especially when you are doing repeated short cuts and touch-up passes throughout the day.

Where this tool separates itself is control. DeWALT built in its ANTI-ROTATION System, which is designed to quickly stop the wheel when a pinch, stall, or bind-up event is detected. In plain terms, if the wheel gets hung up, the tool is designed to react faster to help reduce the sudden twist that can catch you off guard. There is also an electronic brake that stops the wheel within about 1.25 seconds after the trigger is released. That is not a throwaway feature on a grinder. It means less waiting between cuts, safer repositioning, and better control when you are moving around material or working overhead.

The body design is built for access. DeWALT calls out the slim, ergonomic grip and smaller gripping diameter, and that is exactly the kind of detail that matters on an angle grinder. When you are reaching into corners, working between installed materials, or making controlled passes on pipe and tube, a bulky housing gets in the way fast. The compact ATOMIC form factor makes this a better fit for fabricators, maintenance techs, mechanical contractors, and anyone doing metal work where a full-size grinder can feel clumsy.

Jobsite practicality is strong here too. The lock-off paddle switch with no-lock-on design is the right move for a grinder meant for control-first work. The forward exhaust system directs air away from the user and helps manage motor heat, which matters when sparks, dust, and hot metal are part of the day. DeWALT also made guard and wheel changes less of a chore. You can convert the included standard Type B guard to a Type A guard with the clip-on guard, and the spindle lock makes wheel swaps faster without juggling extra wrenches.

If you are already invested in DeWALT cordless tools, the platform fit is straightforward. This grinder runs on the DeWALT 20V MAX battery system and is sold as a bare tool, so batteries and charger are not included. It is also TOOL CONNECT CHIP READY, which means users who need asset tracking and jobsite location features can add the optional chip separately. That will matter more to fleet users and larger crews than to a one-man shop, but it is a useful option to have.

Who should buy it? If you need a compact cordless angle grinder for steel pipe, strut, weld cleanup, maintenance work, field fabrication, or general metal cutting, this one makes a lot of sense. If your work is mostly quick cuts, touch-ups, overhead use, or tight access, the smaller ATOMIC package is the real selling point. If you spend all day leaning on a grinder for heavy stock removal, you may still prefer a larger-body model. But for mobility, access, and control on the DeWALT 20V MAX platform, this is the kind of grinder that earns a spot in the truck fast.

Built for Tight-Space Metal Work

This is where a compact cordless grinder pays off. The shorter, slimmer body is easier to position on pipe, tubing, and installed steel when a larger grinder starts fighting you for space.

• 4-1/2 in. angle grinder format for common cutting and grinding tasks
• Slim ergonomic grip helps with control in confined work areas
• Brushless motor delivers up to 760 MWO for real cutting and grinding output

Control When the Wheel Binds

Grinders get sketchy fast when a wheel pinches. DeWALT added features here that are meant to help you keep command of the tool instead of reacting after the fact.

• ANTI-ROTATION system helps reduce reactionary torque during pinch, stall, or bind-up events
• Electronic brake stops the wheel within about 1.25 seconds after trigger release
• Lock-off paddle switch and no-lock-on design favor control-first use

Quick Changes Keep You Moving

Small details matter on a grinder you use all day. Fast wheel swaps and easy guard changes save time, especially when you move between cutting and grinding work.

• Spindle lock simplifies wheel changes
• Included Type B guard converts to Type A with the clip-on guard
• Forward exhaust helps direct air away from the user and manage motor heat

What’s in the Box

• (1) DeWALT DCG402 ATOMIC 20V MAX 4.5 in. Angle Grinder
• (1) Type B Guard with Type A Clip-on Guard
• (1) Type 27 Grinding Wheel
• (1) Wrench
• (1) Side Handle

Battery and charger are not included.

Key Specifications

Compatibility

Battery Platform Part of the DeWALT 20V MAX system. Battery and charger are sold separately. Jobsite Tracking TOOL CONNECT CHIP READY for use with the optional DeWALT TOOL CONNECT chip and app. Guard Setup Includes a standard Type B guard and a Type A clip-on guard for quick conversion.

Built For

MetalworkingConstructionGeneral ContractingMechanical TradesWeld CleanupPipe CuttingJobsite GrindingMaintenance Work

Pro Tip

If you are bouncing between cutting and grinding, keep the included guard setup sorted before you start the job. The quick guard conversion and spindle lock save real time, but only if you set the tool up for the right wheel before climbing the ladder or heading into a tight mechanical room.

Warranty & Support

3 Year Limited Warranty, 1 Year Free Service, and 90 Day Satisfaction Guaranteed.

Tool Nut’s Take

Tool Nut’s Take

DeWALT DCG402B 20V MAX ATOMIC 4.5-in. Angle Grinder That Actually Makes Compact Worth It

This is the kind of grinder that makes sense for guys who want cordless mobility and tight-access control without ending up with a watered-down tool.

• Who it’s for: Metalworkers, mechanical contractors, maintenance crews, and DeWALT 20V MAX users who need a compact grinder for pipe, weld cleanup, and quick field cuts.
• Why it stands out: You get 11,000 RPM, brushless performance, fast brake response, and the ANTI-ROTATION system in a smaller ATOMIC body that is easier to handle in awkward spots.
• Worth knowing: It is a bare tool, so plan on bringing your own battery and charger. If your work is nonstop heavy grinding, a larger grinder may still be the better pick.

Common Questions

• Is this a cordless or corded grinder? It is a cordless angle grinder powered by the DeWALT 20V MAX battery platform.
• What size wheel does it use? This model is a 4-1/2 inch angle grinder.
• How fast does it run? The no-load speed is 11,000 RPM.
• Does it have a brake? Yes. It uses an electronic brake designed to stop the wheel within about 1.25 seconds after the trigger is released.
• Can it be tracked with DeWALT’s app? It is TOOL CONNECT CHIP READY, which means it can work with the optional TOOL CONNECT chip and app.