# exponent The exponent of the floating-point value. ``` var exponent: Int { get } ``` ## Discussion The *exponent* of a floating-point value is the integer part of the logarithm of the value’s magnitude. For a value `x` of a floating-point type `F`, the magnitude can be calculated as the following, where `**` is exponentiation: ``` x.significand * (F.radix ** x.exponent) ``` In the next example, `y` has a value of `21.5`, which is encoded as `1.34375 * 2 ** 4`. The significand of `y` is therefore 1.34375. ``` let y: Double = 21.5 // y.significand == 1.34375 // y.exponent == 4 // Double.radix == 2 ``` The `exponent` property has the following edge cases: - If `x` is zero, then `x.exponent` is `Int.min`. - If `x` is +/-infinity or NaN, then `x.exponent` is `Int.max` This property implements the `logB` operation defined by the [IEEE 754 specification](http://ieeexplore.ieee.org/servlet/opac?punumber=4610933). --- 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)