if it can hold A LOT more...it must be larger than 512mb. like I sd it depends on the length and bit rate of the MP3 file itself... but if it holds MANY more than that it will be bigger than 512mb. I am an electronics freak.... I KNOW MY STUFF... just saying....I use the basic rule of 1 minute per 1 MG. Therefore a 1 GB player will hold around 1000 minutes. Average 4 minutes per song = 250 songs. I always look at it by number of cd's I can fit. If a cd averages 60 minutes (1 hour), then you can fit 16-17 cd's on a 1 GB player .....so 512 would be approximately half that... nice listing tho.