---
title: significandWidth
framework: swift
role: symbol
role_heading: Instance Property
path: swift/double/significandwidth
---

# significandWidth

The number of bits required to represent the value’s significand.

## Declaration

```swift
var significandWidth: Int { get }
```

## Discussion

Discussion If this value is a finite nonzero number, significandWidth is the number of fractional bits required to represent the value of significand; otherwise, significandWidth is -1. The value of significandWidth is always -1 or between zero and significandBitCount. For example: For any representable power of two, significandWidth is zero, because significand is 1.0. If x is 10, x.significand is 1.01 in binary, so x.significandWidth is 2. If x is Float.pi, x.significand is 1.10010010000111111011011 in binary, and x.significandWidth is 23.

## See Also

### Working with Binary Representation

- [bitPattern](swift/double/bitpattern.md)
- [significandBitPattern](swift/double/significandbitpattern.md)
- [exponentBitPattern](swift/double/exponentbitpattern.md)
- [significandBitCount](swift/double/significandbitcount.md)
- [exponentBitCount](swift/double/exponentbitcount.md)
- [radix](swift/double/radix.md)
- [init(bitPattern:)](swift/double/init(bitpattern:).md)
- [init(sign:exponentBitPattern:significandBitPattern:)](swift/double/init(sign:exponentbitpattern:significandbitpattern:).md)
- [init(nan:signaling:)](swift/double/init(nan:signaling:).md)
- [Double.Exponent](swift/double/exponent-swift.typealias.md)
- [Double.RawSignificand](swift/double/rawsignificand.md)
- [Double.RawExponent](swift/double/rawexponent.md)