bytes to human readable string

Question

I am using the following code to convert bytes to human readable file size. But it's not giving accurate result.

public static class FileSizeHelper
{
    static readonly string[] SizeSuffixes = { "bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
    public static string GetHumanReadableFileSize(Int64 value)
    {
        if (value < 0) { return "-" + GetHumanReadableFileSize(-value); }
        if (value == 0) { return "0.0 bytes"; }

        int mag = (int)Math.Log(value, 1024);
        decimal adjustedSize = (decimal)value / (1L << (mag * 10));

        return string.Format("{0:n2} {1}", adjustedSize, SizeSuffixes[mag]);
    }
}

Usage:

FileSizeHelper.GetHumanReadableFileSize(63861073920);

It returns 59.48 GB
But if I convert the same bytes using google converter it gives 63.8GB.
Any idea what is wrong in the code?

Goolge screenshot:

@René Vogt and @bashis thanks for explanation. finally get it working using following code

public static class FileSizeHelper
{
    static readonly string[] SizeSuffixes = { "bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
     const long byteConversion = 1000;
    public static string GetHumanReadableFileSize(long value)
    {

        if (value < 0) { return "-" + GetHumanReadableFileSize(-value); }
        if (value == 0) { return "0.0 bytes"; }

        int mag = (int)Math.Log(value, byteConversion);
        double adjustedSize = (value / Math.Pow(1000, mag));


        return string.Format("{0:n2} {1}", adjustedSize, SizeSuffixes[mag]);
    }
}

Answer 1

There is always a little confusion about how to display bytes. Your code is correct if the result is what you are trying to achieve.

What you showed from Google is a decimal representation. So just as you say 1000m = 1km, you can say 1000byte = 1kB.

On the other hand, there is the binary representation where 1k = 2^10 = 1024. These representations are called kibiBytes, Gibibytes etc.

Which representation you choose is up to you or the requirements of your customers. Just make obvious which you use to avoid confusion.