The molar ionic conductivity of each ionic species is proportional to its electrical mobility (μ), or drift velocity per unit electric field, according to the equation
where z is the ionic charge, and F is the Faraday constant.
The limiting molar conductivity of a weak electrolyte cannot be determined reliably by extrapolation. Instead it can be expressed as a sum of ionic contributions, which can be evaluated from the limiting molar conductivities of strong electrolytes containing the same ions. For aqueous acetic acid as an example, 
Values for each ion may be determined using measured ion transport numbers. For the cation:
and for the anion:
Most monovalent ions in water have limiting molar ionic conductivities in the range of . For example:
The order of the values for alkali metals is surprising, since it shows that the smallest cation Li moves more slowly in a given electric field than Na, which in turn moves more slowly than K. This occurs because of the effect of solvation of water molecules: the smaller Li binds most strongly to about four water molecules so that the moving cation species is effectively . The solvation is weaker for Na and still weaker for K. The increase in halogen ion mobility from F to Cl to Br is also due to decreasing solvation.
Exceptionally high values are found for H () and OH (), which are explained by the Grotthuss proton-hopping mechanism for the movement of these ions. The H also has a larger conductivity than other ions in alcohols, which have a hydroxyl group, but behaves more normally in other solvents, including liquid ammonia and nitrobenzene.
For multivalent ions, it is usual to consider the conductivity divided by the equivalent ion concentration in terms of equivalents per litre, where 1 equivalent is the quantity of ions that have the same amount of electric charge as 1 mol of a monovalent ion:  mol Ca,  mol ,  mol Al,  mol , etc. This quotient can be called the equivalent conductivity, although IUPAC has recommended that use of this term be discontinued and the term molar conductivity be used for the values of conductivity divided by equivalent concentration. If this convention is used, then the values are in the same range as monovalent ions, e.g.  for  Ca and  for  .
From the ionic molar conductivities of cations and anions, effective ionic radii can be calculated using the concept of Stokes radius. The values obtained for an ionic radius in solution calculated this way can be quite different from the ionic radius for the same ion in crystals, due to the effect of hydration in solution.