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# maximumFileSizeInBits

The minimum number of bits needed to represent, as a signed integer value, the maximum size of a regular file allowed in the volume.

```
optional var maximumFileSizeInBits: Int { get }
```

## Discussion

The maximum file size is `2^(maximumFileSizeInBits - 1)`.

|Maximum file size (bytes) |Maximum (in hex)    |Unsigned bits|Signed bits|
|-------------------------:|-------------------:|------------:|----------:|
|65,535                    |`0xFFFF`            |16           |17         |
|2,147,483,647             |`0x7FFFFFFF`        |31           |32         |
|4,294,967,295             |`0xFFFFFFFF`        |32           |33         |
|18,446,744,073,709,551,615|`0xFFFFFFFFFFFFFFFF`|64           |65         |

Implement at least one of [`maximumFileSize`](/documentation/FSKit/FSVolume/PathConfOperations/maximumFileSize) or `maximumFileSizeInBits`.
FSKit automatically converts from one to another if needed.
If you implement both, FSKit uses only the `maximumFileSizeInBits` implementation.

---

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