Data Storage Converter

Digital data is measured in bits and bytes, with multiples such as kilobytes, megabytes, gigabytes and terabytes. This converter also supports the binary IEC units: kibibytes, mebibytes and gibibytes.

It is useful for understanding file sizes, storage capacity and the difference between decimal and binary measurements.

There are two competing definitions of the storage prefixes, and the mismatch between them is the single most common source of confusion about file sizes.

Drive manufacturers use decimal SI prefixes, where a terabyte is 1,000,000,000,000 bytes. Windows reports using binary multiples of 1,073,741,824 bytes while still labelling them GB. Nothing is missing. The two are counting in different bases.

• 1 kB decimal = 1,000 bytes; 1 KiB binary = 1,024 bytes (2.4% larger).
• 1 MB decimal = 1,000,000; 1 MiB binary = 1,048,576 (4.9% larger).
• 1 GB decimal = 1,000,000,000; 1 GiB binary = 1,073,741,824 (7.4% larger).
• 1 TB decimal = 1,000,000,000,000; 1 TiB binary = 1,099,511,627,776 (10% larger).

The gap widens with each step, which is why a 1 TB drive shows as roughly 931 GB in Windows and about 1 TB on macOS, which switched to decimal reporting. This converter uses decimal SI prefixes throughout.