What Do You Mean a 4.7 GB DVD Won’t Hold 4.7 Gigabytes?
With computers, memory and disk size are commonly expressed in terms such as kilobyte,
megabyte, and gigabyte. Technically, a kilobyte should represent 1000 bytes, but due to
the binary numbering system computers use, a kilobyte actually represents 1024 bytes.
Similarly, a megabyte represents 1,048,576 bytes (and not 1,000,000 bytes) and a gigabyte
represents 1,073,741,824 bytes (and not 1,000,000,000 bytes).
Unfortunately, with DVD discs the terms megabyte and gigabyte do not use the same
binary-based standard; they literally refer to the technically accurate 1,000,000 bytes for
a megabyte and 1,000,000,000 bytes for a gigabyte. This means that a 4.7 GB DVD disc
will actually hold only 4.37 binary-based gigabytes. While the difference is not large
(relatively speaking), it must be accounted for if you intend to come close to filling the
Planning Your Project
When displaying estimated sizes, DVD Studio Pro uses the “1000 bytes equals
a kilobyte” system. This means that the estimated sizes refer to the amount of space they
will require on the DVD and will be a bit larger than the file sizes shown in the Finder.
While the Finder shows binary-based file sizes, you can use its File > Get Info command
to see both the binary-based file size and, in parentheses, the “1000 bytes equals a kilobyte”