binary to decimal vba code

how to convert binary to decimal in vba code

Sub bd()
Funcion Bin2Dec(binVal As String) As Long
Dim binary As Double
Dim iLen As Integer
binVal = Range("c4").Value

iLen = Len(binVal) - 1
For binary = 0 To iLen
    bin2dec = bin2dec + _
      Mid(binVal, iLen - x + 1, 1) * 2 ^ x
Next

End Function
End Sub