What does kilobyte mean?
A kilobyte is a unit of digital information, conventionally equal to 1,000 bytes. It is used to describe the size of files, documents, images, web pages, and other computer data. The abbreviation KB is common, although the technically preferred symbol under the International System of Units is kB. In earlier computing environments, a kilobyte often meant 1,024 bytes because that number is a power of two and therefore convenient for binary storage. Modern standards reserve the term kibibyte (KiB) for exactly 1,024 bytes, helping to distinguish binary storage measurements from decimal ones. The word is useful in technical contexts because it provides a familiar intermediate measure between individual bytes and larger units such as the megabyte and gigabyte. Although everyday references may still treat it as synonymous with 1,024 bytes, current standards normally define one kilobyte as 1,000 bytes.
nounA unit of information equal to 1,000 bytes in the decimal system. Historically, the term was also sometimes used for 1,024 bytes, especially in computer-memory contexts.
- A unit of digital information equal to 1,000 bytes in the decimal system.
- An older or informal unit equal to 1,024 bytes, particularly in contexts describing computer memory.
"The compressed document is only twenty kilobytes, so it should upload quickly."
"Each page adds roughly two kilobytes to the size of the file."
"The old system reported its available memory in kilobytes rather than megabytes."
Use the plural when referring to multiple units or an unspecified quantity of data.
"The report contains only a few kilobytes of text."
One kilobyte is 1,000 bytes today, but generations of computers treated it as 1,024—the number that makes binary arithmetic convenient.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kilobyte come from?
Kilobyte was formed in the twentieth century by combining the metric prefix kilo-, derived from Greek meaning “thousand,” with byte, the fundamental unit of digital information. The two elements reflect the word's original sense of a thousand units of computer memory or data, while its later history reflects the traditional binary meaning of 1,024 bytes.
How kilobyte is actually used
Under the International System of Units, the standard symbol is kB and represents exactly 1,000 bytes. The capitalized abbreviation KB is widespread but less precise. Computer professionals and older software sometimes use the term for 1,024 bytes, a usage now formally distinguished by the kibibyte, or KiB.
Easily confused with kilobyte
A kilobyte is conventionally 1,000 bytes, whereas a kibibyte is exactly 1,024 bytes.
A kilobyte contains 8,000 bits, while a kilobit contains 1,000 bits.