How much space to leave in SSD?

Backspace

I have a 500 gig SSD as primary and OS drive. It's the first time I even used one but I have a Seagate Enterprise 1 TB spin drive as a secondary drive. I've read that for the SSD it need some unused space for optimal operations.

I don't think I'll have that problem in that respect as I'm only using 51 gig and I got the Crucial MX500 SSD because it was only $58. Works very good.

So what % of space are you expected to leave free?

EndlessWaves

It depends on the controller and even with drives on the same controller it'll likely vary depending on things like the number of flash chips and whether it has any cache RAM.

But I wouldn't expect it to be much more than 10% on any drive, maybe 20% at the outside. Some drives may be considerably less.

PadPoet

This. As a general rule of thumb if you don't fill it up more than 70-80% you won't notice any real performance loss.