DVDs only 4.5 GBs?

Hello all, I am experienceing some really weird dvd issues on my imac G3 500mhz with external firewire dvd drive. It only recognizes my dvds as 4.5 Gbs when they are 4.7 plus this never happened when I had panther. Not only is this the case finder but also in Toast 6.1.1 what is the deal?

Take whatever size they are telling you and multiply it by 1.024 and you should come up with 4.7gb's. DVD's are the same as hard drives, the advertised size is always more then it really is

Aren't the dual layer ones more?

The dual layer should be double the size of a regular DVD, about 8.5GB.

You see, your DVD will need to give up some space for the sake of storing information on the data structure on the disc, file system information and such. So you cannot use all 4.7GB ever, even on a way much cooler windows peesee.