Ryobi 18-Volt ONE+ 4-1/2 in. Angle Grinder (Tool-Only)-P421 - The Home Depot
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Model # P421

Internet # 100519983

Store SKU # 152332

18-Volt ONE+ 4-1/2 in. Angle Grinder (Tool-Only)

Ryobi 18-Volt ONE+ 4-1/2 in. Angle Grinder (Tool-Only)

This item has been discontinued.
The Home Depot no longer carries this specific product.

$39.97 / each
  • Over 50 great ONE+™ tools work with the same 18V battery platform
  • Any 18V ONE+™ blue or green tool works with any 18V ONE+™ battery
  • Up to 6,500 RPMs enable fast and precise work


Model # P421

Internet # 100519983

Store SKU # 152332

The RYOBI 18-Volt ONE+ 4-1/2 in. Angle Grinder offers cordless convenience and the power of 6500 RPM for fast and precise work. This tool offers a host of user-friendly features, such as onboard wrench storage, a comfortable overmolded grip and a 3-position side handle to help reduce fatigue. It also has an intuitive trigger switch.

California residents: see  Proposition 65 information

Info & Guides

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Assembled Depth (in.) 
13.7 in 
Assembled Height (in.) 
5.443 in 
Assembled Width (in.) 
5.669 in 
Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Wheel Diameter (in.) 
4.5 in 
Amperage (amps) 
Arbor Size 
5/8 x 11 UNC 
Batteries Included 
Battery Power Type 
Lithium Ion 
Battery Size 
Lithium Ion 
Charger Included 
Color Family 
Cordless Tool Type 
Angle Grinder 
Grinding Wheel Included 
Maximum Speed (rpm) 
Power Tool Product Type 
Product Weight (lb.) 
6.18 lb 
Side Handle 
Spindle Lock 
Tools Product Type 
Power Tool 
Variable Speed 
Voltage (volts) 
Warranty / Certifications
Certifications and Listings 
1-UL Listed 
Manufacturer Warranty 
3 Year Limited Warranty 


Rated 4.3 out of 5 by 97 reviewers.
Rated 4.0 out of 5.0 by Handy grinder I have used this grinder to sharpen my lawnmower blade wihout removing it from the lawnmower and it did a good job. I have also installed a steel cut off blade to cut through metal closet door hardware and it worked great. December 26, 2008
Rated 5.0 out of 5.0 by Great grinder. Little bit of a battery hog. I love this grinder. It's a 5/8 spindle 11UNC. So it's easy to find wheels for. It only takes type 27, and not flat wheels, so make sure you get the right type. But slap a battery in this sucker and it's off to the races. Battery life is as to be expected..about 10 minutes on a compact lithium ion battery. I have 3, so I can get some solid work done while charging one. I'll be looking at a couple 4ah in the future. Overall, great grinder. Comfortable. Good balance. My hands never got tired. Has the fit and finish to last a good long time, and enough beans to knock down a weld. May 18, 2015
Rated 4.0 out of 5.0 by Good tool for smaller jobs I have been using this tool to open up some cracks in my garage floor in order to fill them and resurface the floor. The tool is great and does its job with a decent diamond blade. However you NEED to buy the high capacity battery for it or else you only get about 5-10 minutes of real working time. Good tool, but chews up battery quick. For bigger jobs a corded tool is better, or dish out the cash for a high capacity battery. May 7, 2014
Rated 5.0 out of 5.0 by High quality and unexpensive RYOBI cordless tools get proffesional work done I have been doing commercial HVAC since mid 2010 and I have used this grinder ever since. The grinder is not as fast as my corded Dewalt. But, in reality, no cordless grinder is going to be as fast as a corded one (regardless of brand name). However, this cordless RYOBI grinder gets the job done. It's supposed to be a DO-IT-YOURSELFER tool, but as a professional HVAC installer, I have used this grinder for professional uses. I have built ductwork in new hospitals, schools, apartment buildings, and super stores (a couple WALMARTS). I would recommend this Ryobi grinder (and any other Ryobi cordless tool) to DO-IT-YOURSELFERS and professionals as well. January 28, 2014
Rated 4.0 out of 5.0 by Works well for ordinary use Some reviewers have had problems with this 4 1/2" angle grinder, including one man in the store who had just returned one that never worked. My experience is different, though. I had to reduce the size of some t-bar metal fence posts and this tool worked well. I used it for about 45 minutes (and drained the 4ah battery) with no signs of problems. The handle remained cool, the job was completed, and only a battery recharge was needed. This is not an industrial angle grinder, but for home, hobby, or as an alternative when electricity or compressed air is not available, it does the job at a slightly slower pace but gets the job done. No regrets at all. April 27, 2015
Rated 5.0 out of 5.0 by 18 volt angle grinder i really like the features on this angle grinder. The guard rotates without being removed and the grinder has plenty of power. October 29, 2014
Rated 5.0 out of 5.0 by Great little grinder. I've used grindes a lot. I use to be a TIG welder back in the '70s and used a grinder a few hours every working day back then and still use them regularly these days. I've used this grinder maybe 20 times so far and ad usual with Ryobi its a great value. So far its had plenty of power ( using the 2x Lion batt ) seems well put together, the trigger and safty work welln easy to swap disc's and I love the lt green color of these tools, makes them easy to see on the job or in the box. I buy tools that are a good value for my regular use, Ryobi over the past 10 years has earned my first consideration when I'm shopping for a new tool. October 1, 2013
Rated 4.0 out of 5.0 by Paint removal on a bicycle frame. Using this in conjunction with the drill for paint removal on a bicycle that I am redoing for a friend. Seems to work well for the purpose for which I bought it May 19, 2015
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