Converting file length into User friendly format (GB, MB, KB, Bytes)

Use following function to convert file length in bytes to user friendly format

 private string FormatByteSize(long length)
        {
            const int KB = 1024;
            const int MB = 1024 * KB;
            const int GB = 1024 * MB;
            if (length > GB)
            {
                return (length / GB).ToString("0.00") + " GB";
            }
            else if (length > MB)
            {
                return (length / MB).ToString("0.00") + " MB";
            }
            else if (length > KB)
            {
                return (length / KB).ToString("0.00") + " KB";
            }
            return length.ToString()+" Bytes";
        }