Simple linear approximations to the specific conductance of a mixture can be written in terms of various solute fractions (molar, equivalent, or ionic strength) and the specific conductances of its constituent binary systems. These binary conductances are evaluated at some type of "constant" concentration which characterizes the mixture (constant total molarity, constant total equivalents, or constant total ionic strength). These expressions can be made exact for fitting experimental data by including a correction term. General forms have been derived for transforming these binary approximations for the specific conductance and their corresponding correction terms to the analogous binary approximations for "concentration conductances" such as molar, equivalent, or ionar (ionic strength) conductance. Conversely, simple binary approximations for any concentration conductance in terms of arbitrary fractions for an arbitrary binary evaluation strategy lead to binary approximations for the specific conductance. In both cases, simpler forms result when "natural" fractions or "natural" binary evaluation strategies are used. The specific conductance is the basic physical property. The NaCl-MgCl2-H2O system is used as an example.