# Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) vs Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only): specs and price compared

A sourced, side-by-side comparison of the Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) (Ryobi) and Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) (Ridgid) among angle grinders. Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) is the cheaper of the two at $49.97.

## Side by side

| Spec | Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) | Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) |
| --- | --- | --- |
| US price | $49.97 | $99 |
| Brand | Ryobi | Ridgid |
| Disc size (in) | 4.5 in | 4.5 in |
| Power source | cordless | cordless |
| Amps or voltage | 18 V | 18 V |
| Max (rpm) | 6500 | 9000 |
| Brushless | No | No |
| Switch type | trigger | slide |
| No volt release | — | — |
| Weight (lb) | 4.8 | 4.5 |

## Key differences

- Max (rpm): Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) 6500 vs Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) 9000
- Switch type: Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) trigger vs Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) slide
- Weight (lb): Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) 4.8 vs Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) 4.5

## What reviewers say

**Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only)** — Only one whitelisted tester, Pro Tool Reviews, hands-on tested this exact R86040B. PTR scored it 8.2/10, praising cordless mobility and strong cutting torque, but flagged fast battery drain (6-7 cuts per charge) and a single fixed speed with no variable control. (1 sourced review.)

## Sources

- Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only): https://www.ryobitools.com/products/33287139576 (ryobitools.com, verified 2026-06-20)
- Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only): https://www.homedepot.com/p/RIDGID-X4-18-Volt-Lithium-Ion-Cordless-4-1-2-in-Angle-Grinder-R86040B/203930490 (homedepot.com, verified 2026-06-20)

Canonical: https://frontdeskreview.com/gear/angle-grinders/ryobi-p421-vs-ridgid-r86040b/
Cite: Per The Front Desk Review, Ryobi P421 18V ONE+ 4-1/2 in. Cordless Angle Grinder (Tool Only) ($49.97) vs Ridgid R86040B 18V X4 4-1/2 in. Cordless Angle Grinder (Tool Only) ($99) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/angle-grinders/ryobi-p421-vs-ridgid-r86040b/
License: CC BY 4.0.