Data size converter - bytes, MB, GB, TB and binary units

Decimal storage prefixes use powers of 1,000. One kilobyte (KB) is 1,000 bytes, one megabyte (MB) is 1,000,000 bytes, and one gigabyte (GB) is 1,000,000,000 bytes. A terabyte (TB) contains 1,000 GB. Storage manufacturers commonly use these decimal definitions when advertising the capacity of a drive.

For example, a drive labelled 1 TB has 1,000,000,000,000 bytes. Dividing that by 1,000,000 gives 1,000,000 MB. The converter uses these standard factors to make large values easier to compare. Bits and bytes are different: one byte contains eight bits, so an internet speed measured in megabits per second cannot be read as megabytes per second without converting and accounting for time.

Binary prefixes use powers of 1,024. One kibibyte (KiB) is 1,024 bytes; one mebibyte (MiB) is 1,048,576 bytes; one gibibyte (GiB) is 1,073,741,824 bytes. These names distinguish binary values from decimal kilobytes, megabytes and gigabytes. The difference grows with each unit: one GiB is about 1.074 GB.

Some software has historically displayed binary quantities using labels such as KB or GB. As a result, a file manager and a drive package may show different-looking capacities for the same number of bytes. The physical data has not changed; the programs are dividing by different factors or rounding the display. Use KiB, MiB and GiB when the binary convention is intended, and KB, MB and GB for decimal quantities.

A file size records an amount of data, while a transfer rate records data per unit of time. To estimate a download duration, convert the file size to bits, then divide by the connection rate in bits per second. For instance, a 100 MB decimal file contains 800 megabits; at a steady 20 Mbps, the ideal transfer time is 40 seconds. Real downloads take longer because of protocol overhead, server performance and network variation.

Drive capacity shown by an operating system can also differ from the number printed on the product box due to decimal versus binary units and space used for formatting or system partitions. This converter helps explain unit math but does not inspect a file, measure a connection or guarantee a download time. Always compare values using the same prefix system and distinguish MB from Mb.