Print File Size

You can keep your output consistent with how Windows represents file sizes by using the inbuilt function;StrFormatByteSize

The following code will dump the files from the root of C:\, Call getFilesAndSizes from a button click or wherever you want.

<System.Runtime.InteropServices.DllImport("shlwapi", CharSet:=System.Runtime.InteropServices.CharSet.Auto)> _
Private Shared Function StrFormatByteSize( _
     ByVal fileSize As Long, _
     ByVal buffer As System.Text.StringBuilder, _
     ByVal bufferSize As Integer
    ) As Long
End Function

Private Sub GetFilesAndSizes()
    dirFiles("C:\")
End Sub

Private Sub dirFiles(ByVal path As String)

    Dim fi As System.IO.FileInfo
    Dim sb As New System.Text.StringBuilder
    Dim files() As String
    Try
        files = System.IO.Directory.GetFiles(path)

        For Each file In files
            fi = New System.IO.FileInfo(file)
            StrFormatByteSize(fi.Length, sb, 128)

            Debug.WriteLine(file & " : " & sb.ToString)
        Next

    Catch ex As Exception
        Debug.WriteLine("Error with: " & path)
    End Try

End Sub

The output generated on my laptop was;

C:\autoexec.bat : 24 bytes
C:\bootmgr : 374 KB
C:\BOOTSECT.BAK : 8.00 KB
C:\config.sys : 10 bytes
C:\hiberfil.sys : 2.24 GB
C:\pagefile.sys : 2.99 GB