This extension method humanizes the file size (FileInfo.Length is long but we need to make it into a decimal to get decimal places (long / long = long).

public static class Extensions

{

	public static readonly long Kb = 1024;

	public static readonly long Mb = 1024 * 1024;

	public static readonly long Gb = 1024 * 1024 * 1024;

	public static string FileSize(this long length)

	{
		decimal size = Convert.ToDecimal(length);

		if (size > Gb)
			return string.Format("{0:#.##} Gb", size / Gb);
		else if (size > Mb)
			return string.Format("{0:#.##} Mb", size / Mb);
		else if (size > Kb)
			return string.Format("{0:#.##} Kb", size / Kb);
		else
			return string.Format("{0} b", size);
	}

}