Why can't i fit 4.7Gb on DVD

Everytime i try to burn data onto a dvd, i can never fit the full 4.7 Gb of data on a disk, its always a few hundread Megabytes less, can anyone tell me why?

They count the bytes differently.
They assume 1,000 bytes is 1 KB, 1,000 KB = 1MB and so on, while in fact it is 1,024 bytes in 1 KB, 1,024 KB in a MB etc.

(in this forum more detailed discussions on this subject can be found)

It is the same with hard drives.
As stated, the manufactures count with 1000, Windows does with 1024.

When e.g. Verbatim says that you can store 4,7Gb they actually mean 4700000000 bytes and 1000 bytes = 1kb

Windows does calculate 10[B]24[/B] bytes = 1kb, so for Windows 4700000000 bytes are 4,37Gb