# exponentBitCount The number of bits used to represent the type’s exponent. ``` static var exponentBitCount: Int { get } ``` ## Discussion A binary floating-point type’s `exponentBitCount` imposes a limit on the range of the exponent for normal, finite values. The *exponent bias* of a type `F` can be calculated as the following, where `**` is exponentiation: ``` let bias = 2 ** (F.exponentBitCount - 1) - 1 ``` The least normal exponent for values of the type `F` is `1 - bias`, and the largest finite exponent is `bias`. An all-zeros exponent is reserved for subnormals and zeros, and an all-ones exponent is reserved for infinity and NaN. For example, the `Float` type has an `exponentBitCount` of 8, which gives an exponent bias of `127` by the calculation above. ``` let bias = 2 ** (Float.exponentBitCount - 1) - 1 // bias == 127 print(Float.greatestFiniteMagnitude.exponent) // Prints "127" print(Float.leastNormalMagnitude.exponent) // Prints "-126" ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)