Blanks say 4.7 why cant we use 4.7?



if the blanks say they hold 4.7 gigs…then why can we only use 4.444 or so??? where does this other 250 MB go???


Try reading this thread.



ummm i read…and it made me even more confused…maybe it was a bad question to ask…way to confusing…


There are 2 definitions of gigabyte:

  1. 2^30 (2 to the 30th power) bytes (1,073,741,824) - this is the definition that your computer uses (the “true” definition)

  2. 1 billion bytes (1,000,000,000) - this is what hard drive manufacturers and DVD-recordable disc makers use

4,700,000,000 / 1,073,741,824 = 4.377 “true” gigabytes on a DVD-recordable disc

It is just a difference in how you define gigabyte, and it’s also a marketing technique.


Actually, that’s the thing… there is no “true” definition because half the industry uses one standard while the other half uses another. The technical definition of gigabyte is one billion bytes (in base 10 that’s 10^9), but since computers count in base 2, a gigabyte is 2^30 (or 1,073,741,824 bytes). That’s why the IEEE is trying to adopt the IEEE 1541 Standard which has different names for base 2 sizes. For example, 2^30, commonly referred to as gigabyte, would now be called gibibyte (abbreviation “GiB”). The rest is outlined in the link.

Incidentally, this is the result you get if you look up the definition of gigabyte at The definitions all contradict each other. Until this is all resolved, people will continue to be confused.



Being a born cynic I wonder if the disk manufacturers would be so keen to be accurate, if the result indicated a smaller size. :bigsmile:

It reminds me of the “confusion” with output, quoted for audio speakers … “How many watts per channel ?” … is that RMS, PMPO into 8ohms or 6 ohms ? :wink: … continuous sine … what’s that ? … a marketeers dream :wink:


yes i once had a car audio amp that had 1600 watts on the front of it,but in reality it only produced 300 watts… very very sneaky…