I was under the impression that 1 MB = 1024 KB = 1048676 bytes, but when I use Get Info to check video file size I see numbers like "473.9 MB on disk (473,910,856 bytes)". Does Get Info use a different method, where 1 MB = 1000000 bytes?
Mac mini, Mac OS X (10.6.8)
The (decimal) mega prefix has always been 1000 x 1000, although when memory sizes were still fairly small it was also used as a binary prefix. The (binary) mebi prefix (1024 x 1024) has been around for a while and is used more often these days, since there can be a significant difference when discussing larger memory sizes - see http://physics.nist.gov/cuu/Units/binary.html. The Get Info window shows sizes in megabytes, since that is what most disk drive manufacturers use.
For years, like from the beginning of computers, various sizes were based on 1024 (powers of 2).
Then Disk Driver manufactures started reporting storage in 1000 (base 10) units because it made their disk drive look bigger than the competition. I think this started around the time disk drives started having gigabyte sized capacities and the difference between base 10 and powers of 2 reporting became a large number.
But the operating systems kept using powers of 2. And users started to complain that they purchased a drive with 500 gigabytes, and the computer said it only had 465 gigabytes, and they blamed the operating systems.
So the operating system vendors caved in and started reporting disk storage in base 10 units.
At least RAM vendors still report memory in powers of 2, so the 16 gigabytes of RAM you purchased is reported as 16 gigabytes of RAM by the operating system and it is a proper power of 2 or 17,179,869,184 bytes of RAM 🙂
How does Get Info calculate how many bytes in a megabyte?
