However, one need only select one substance as a reference standard, and tabulate the free energies or voltages for reactions of all other substances with this standard. The free energy of a cell not involving the standard substance then can be found by subtracting one of these reactions from another, and subtracting free energies in the same way. The contribution of the "standard" reaction cancels out.

The standard half-reaction that has been chosen is the oxidation of hydrogen gas to hydrogen ions in solution:

Pairing the zinc, nickel, and copper half-reactions separately with this half-reaction leads to the following tabulation: