We propose limits to the contributions to the total inner membrane potential by lipid head group components and by the orientation of water.  These assessments are based on electrostatic calculations that were an integral part of our explanation of the photogating of ionic currents across the lipid bilayer.  Our purpose is to describe an easy, fast method to calculate and examine the electrostatic consequences of various membrane structures and orientations, not to get embroiled in controversies regarding membrane structure.  We do show how variations in these membrane dimensions and structures affect the dipole potential of the membrane by using a range of values quoted in the literature.   The averages of these ranges are used as the parameters to calculate the total membrane potential.