File Size Converter

KB (kilobyte, decimal/SI) equals exactly 1,000 bytes, while KiB (kibibyte, binary/IEC) equals exactly 1,024 bytes — the same pattern continues at every larger unit (MB vs MiB, GB vs GiB, and so on), which is why a "500 GB" hard drive shows up as roughly 465 GiB in your operating system.

Storage manufacturers market capacity in decimal (SI) units because it makes the advertised number look larger and matches the international standard for metric prefixes, while most operating systems (especially older Windows versions) historically reported binary (IEC) units under the same KB/MB/GB labels — causing the mismatch you see between a drive's advertised and reported capacity.

It depends on the context — use decimal (1000-based) if you're matching marketing/storage-vendor conventions or network transfer specs, and binary (1024-based) if you're matching how most operating system file managers and RAM capacities are actually reported; being explicit with IEC unit names (KiB, MiB) in your own UI avoids ambiguity entirely.

Yes — it includes petabyte (PB/PiB) as the largest unit option, and very large or very small results are automatically switched to scientific notation for readability.

Yes — pick any unit as your input (for example, entering 2.5 in the GB/GiB field), and the tool shows the equivalent value in every other unit, both smaller and larger, in both systems simultaneously.