Data Storage Converter

Convert between bytes, kilobytes, megabytes, and gigabytes, with the binary vs. decimal prefix confusion explained.

Why a “Gigabyte” Doesn’t Always Mean the Same Number of Bytes

Data storage conversion carries a genuine, long-running source of confusion, because the industry has never fully agreed on whether prefixes like kilo, mega, and giga should mean powers of ten, consistent with every other measurement system, or powers of two, which is more natural for how computers actually organize memory. Under the strict decimal interpretation, a kilobyte is exactly one thousand bytes, consistent with kilo meaning a thousand everywhere else in science. But because computer memory is organized in binary, addressed in powers of two, storage manufacturers and operating systems have historically used “kilobyte” to mean 1,024 bytes instead, since 1,024 is the nearest power of two to one thousand, a convenient but technically inconsistent shortcut that compounds at every larger prefix, meaning a “gigabyte” under the binary interpretation is noticeably larger than a decimal gigabyte. This exact discrepancy is why a storage drive advertised at a round decimal capacity often shows a smaller, less round number once plugged into a computer that reports capacity using the binary interpretation instead, a gap that has caused genuine consumer confusion and even litigation over the years. To resolve the ambiguity, an international standard now defines separate binary prefixes, kibibyte, mebibyte, and gibibyte, specifically meaning the powers-of-two values, though these more precise terms still haven’t fully replaced the older, ambiguous usage in everyday language.