It says 512 MB, but when I first put mine in it said 468 MB or something, either way, this is still a GREAT memory stick for the price. ( I can't believe it's so cheap on Amazon, at best buy mine was 80 bucks. ) Definite must buy for anybody with a PSP that wants to take full advantage of its capabilities. Notes: I have about 6 spongebob squarepants episodes on my PSP. ( 11 minutes or so long ) and there is still PLENTY of space left on my memory stick. I had 95 songs on this memory stick and had PLENTY of space left. You should have absolutely no problem getting 120 or so songs on this thing, assuming they are 2-4 minutes in length. So think about this: An Ipod Shuffle holds about 100 and it costs 100 dollars, or you can buy a memory stick that is 50 dollars or so that can hold 120 or more. BUY IT!! IT WORKS GREAT!!