Input Box Valdation

In what format will it be entered?

As a number followed by %
just as a number without the %

You will need to test for several different entries

With Me.TextBox1
   If .Value = "" Then
      Exit Sub
   End If
   If Not Right(.Value, 1) = "%" Then
      Exit Sub
   End If
   If Not IsNumeric(Left(.Value, Len(.Value) - 1)) Then
      Exit Sub
   End If
End With

In the above code a space between the number & the % symbol will test as a valid entry. A space anywhere else will not pass the test

If you want to test for a space between the number & the % then also use

   If InStr(.Value, " ") > 0 Then
      Exit Sub
   End If

before the End With command