A big desk mat quiets your keyboard more than a small mousepad.

Yes, but mostly for the keyboard, not the mouse.

A small mousepad only sits under your mouse, so your keyboard is still clacking directly on the desk. A full desk mat covers that whole area, adding a layer of felt, foam, or fabric between your keyboard and the hard surface. That soft material absorbs some of the vibration and high-frequency noise, especially if you bottom out your keys.

The difference in mouse click sound is minimal, since your mouse is already on a pad. The bigger change is in the overall reverb — the desk mat kills the echo off the bare desk. If your keyboard is loud, a thick desk mat helps more than a thin one.

That said, if you’re hoping for silent typing, a desk mat alone won’t get you there. You’d need to swap your keyboard switches or add o-rings. The mat just takes the edge off.

Worth trying if your desk is a hard surface and you hate the echo.