If you want to display the size of a file to the user simply doing the following will result in the size of the file in bytes:

new FileInfo(PathToMyFile).Length

However that's fairly useless in today's world of bigger and bigger files so along comes this neat bit of code:

public static string GetFileSizeAsString(long size)
{
    double s = size;
    string[] format = new string[] { "{0} bytes", "{0} KB",  "{0} MB", "{0} GB", "{0} TB", "{0} PB", "{0} EB", "{0} ZB","{0} YB" };
    int i = 0;
    while (i < format.Length-1 && s >= 1024)
    {
       s = (int)(100 * s / 1024) / 100.0;
       i++;

    }
    return string.Format(format[i], s.ToString("###,###,###.##"));           
}

This will return you the following strings (depending on how big the file is...)

• 160 bytes
• 345 KB
• 34.7 MB
• 1.2 GB
• 1.76 TB
• 8.19 PB and so on...

If you get a file bigger than an 1,024 Yottabytes (YB) then tough! I'm sure you'll agree its not really that much of a limitation!