Bitlength

Bitlength is the number of bits used to represent a value in a binary encoding, or the length of a bit string or field. It is a fundamental property of data types and data formats, informing how much information a value can convey and how much storage it requires. In practice, fixed-length representations commonly use 8, 16, 32, or 64 bits.

For unsigned integers, n bits can represent 2^n distinct values (0 to 2^n−1). For signed integers in two's complement, the range is −2^(n−1) to 2^(n−1)−1. Bitlength also determines the capacity of bit strings; for example, an n-bit string has 2^n possible patterns.

Some systems support arbitrary-precision integers, whose bitlength grows with the magnitude of the value. In such cases, the storage is not fixed, and the bitlength is a dynamic property of the number.

Bitlength is used in data formats to specify the length of a field or a data unit, and in cryptography to describe key sizes (for example, a 2048-bit RSA key). The term is related to, but not identical with, word size or machine width, which describe the processor’s typical data path size.

Examples: 8-bit characters (ASCII) and 16-bit units in UTF-16; many modern systems use 32-bit or 64-bit representations for Unicode code points in internal formats. Bitlength thus characterizes both the information content and the storage requirements of data.

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