---
title: significand
framework: swift
role: symbol
role_heading: Instance Property
path: swift/float/significand
---

# significand

The significand of the floating-point value.

## Declaration

```swift
var significand: Float { get }
```

## Discussion

Discussion The magnitude of a floating-point value x of type F can be calculated by using the following formula, 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 If a type’s radix is 2, then for finite nonzero numbers, the significand is in the range 1.0 ..< 2.0. For other values of x, x.significand is defined as follows: If x is zero, then x.significand is 0.0. If x is infinite, then x.significand is infinity. If x is NaN, then x.significand is NaN. note: The significand is frequently also called the mantissa, but significand is the preferred terminology in the IEEE 754 specification, to allay confusion with the use of mantissa for the fractional part of a logarithm.

## See Also

### Querying a Float

- [ulp](swift/float/ulp.md)
- [exponent](swift/float/exponent-swift.property.md)
- [nextUp](swift/float/nextup.md)
- [nextDown](swift/float/nextdown.md)
- [binade](swift/float/binade.md)