Kilobyte

The kilobyte is a multiple of the unit byte for digital information. The International System of Units (SI) defines the prefix kilo as a multiplication factor of 1000 (103); therefore, one kilobyte is 1000 bytes. The internationally recommended unit symbol for the kilobyte is kB. In some areas of information technology, particularly in reference to solid-state memory capacity, kilobyte instead typically refers to 1024 (210) bytes. This arises from the prevalence of sizes that are powers of two in modern digital memory architectures, coupled with the coincidence that 210 differs from 103 by less than 2.5%. A kibibyte is defined by IEC 80000-13 as 1024 bytes. In the International System of Units (SI) the prefix kilo means 1000 (103); therefore, one kilobyte is 1000 bytes. The unit symbol is kB. This is the definition recommended by the International Electrotechnical Commission (IEC). This definition, and the related definitions of the prefixes mega (1 000 000), giga (1 000 000 000), etc., are most commonly used for data transfer rates in computer networks, internal bus, hard drive and flash media transfer speeds, and for the capacities of most storage media, particularly hard drives, flash-based storage, and DVDs. It is also consistent with the other uses of the SI prefixes in computing, such as CPU clock speeds or measures of performance. The IEC 80000-13 standard uses the term 'byte' to mean eight bits (1 B = 8 bit). Therefore, 1 kB = 8000 bit. One thousand kilobytes (1000 kB) is equal to one megabyte (1 MB), where 1 MB is one million bytes. The term 'kilobyte' has traditionally been used to refer to 1024 bytes (210 B). The usage of the metric prefix kilo for binary multiples arose as a convenience, because 1024 is approximately 1000. The binary interpretation of metric prefixes is still prominently used by the Microsoft Windows operating system. Metric prefixes are also used for random-access memory capacity, such as main memory and CPU cache size, due to the prevalent binary addressing of memory.