Ryobi ZRP421 One+ 18V Cordless 4-1/2″ Angle Grinder Review

By Tool Scout | Angle Grinder Reviews

Ryobi ZRP421 One+ 18V Cordless 4-1/2

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Quick Overview





  • Affordable
  • 3-position side handle
  • Lightweight
  • Compatible with all P100 series batteries
  • Easy to use


  • Low power

Ryobi is known for making high-quality, durable power tools, particularly the cordless variety, that can get the job done no matter what. This One+ series of 4-1/2” cordless angle grinder is an excellent buy if you have small- and medium-sized DIY home projects to complete.

It's a portable battery-power so you can take your work anywhere you want. So, if you need a reliable power tool that can help you complete a wide range of projects at home, this angle grinder should definitely make it to your list, more so if you already own Ryobi ONE+ battery-powered tools.

Ryobi ZRP421 One+ 18V Cordless 4-1/2" Angle Grinder

What we have here is a compact yet highly efficient cordless tool suitable for all kinds of applications. It has some useful features that will help you finish any grinding, cutting, sanding, sharpening, and polishing DIY jobs at home. It's not the most powerful angle grinder on the market, but it's still powerful enough to cut metal, ceramic tiles, grind off rust and corrosion, and so much more. The tool doesn't come with a One+ battery, but it works with all Ryobi P100 series of batteries.

What to expect

Ryobi has a long tradition in power tools, so they know precisely what a useful tool looks like. This particular cordless angle grinder is suitable for all kinds of small and mid-level home projects. It's good for beginners because it's effortless to master and use. Furthermore, since there are no cables, you won't have to step over them and watch your footing all the time. The motor can produce up to 6,500 RPM, and the work time depends on the battery you buy. All in all, it's a great little tool to use for DIY projects, even in remote locations.

The downside is that there are no batteries included. Also, if you're looking for a fearless professional tool that can take on anything, this could be the wrong choice. Battery-powered devices have a limited run time, so you can't use them for a long time without running out of batteries. It has a 6,500 no-load RPM, which won't be enough for heavy-duty professional applications. The fact that it doesn't come with batteries or a charger can complicate things further if you don't already own a Ryobi One+ tool.

What's included?

Sadly, this tool doesn’t come with a battery or a charger. You will have to buy a P100 series battery (the bigger, the better) and the One+ fast charger. However, the purchase does include a side handle, one grinding wheel, and a spanner wrench for quick wheel changes. You get everything you need, except the battery, but if you already own any cordless Ryobi tools, that may not be a problem.

Features overview

When compared to similar tools, this Ryobi cordless angle grinder has only the basic features without any extras or complications. It delivers up to 6,500 RPM, enough for small to medium home projects. You can move the guard without any extra tools. There's an onboard wrench storage compartment for the tool you need to change the wheel.

The GripZone over-mold provides a secure grip and improves comfort. The tool has an ergonomic design, so you won't feel much fatigue even after prolonged use. The side handle has three available positions, so you can switch to either one, depending on the task at hand. You also have a trigger switch that's very easy to use.

When you let go of it, the motor will stop the wheel in a second. The tool weighs 4.6 pounds without the battery. Get a bigger one if you don't want to think about your battery level all the time. You can use this cordless angle grinder for a wide range of materials and home improvement jobs.

How to use

Using this power tool is very straightforward. You only need to pair it with an 18V One+ battery, and you're ready to go. Press the finger trigger, and the wheel will start turning. You can use the tool for all kinds of tasks. Just make sure that the batteries are charged before you use it because it takes about two hours to charge in full. You can switch the position of the handle and the guard, so the angle grinder can fit either of your hands.


Since this tool comes without a battery, you’ll have to spend extra on one. Furthermore, it works at only 6,500 RPM, which is good for a cordless power tool but not enough for heavy-duty tasks and projects. If you want to buy an angle grinder that can cope with anything you throw at it, you’ll need something like the WEN 4-1/2-Inch Angle Grinder.

It's an AC-powered unit that produces up to 11,000 RPM, which should be all you need for any task. It also comes with a bunch of useful accessories and other features designed to make the toughest jobs more manageable.


There's not much to this Ryobi cordless angle grinder. It's a bare tool with essential features like a 3-position handle and a trigger switch that's straightforward to use, so it's suitable for beginners. It won't help you if you have a lot of grinding and cutting to do, but it will prove its worth on small DIY home projects and other jobs. You need to own a One+ battery, or you'll have to buy it separately for use with this tool.

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