# Determining number of electrons transferred

When determining the number of electrons transferred in a redox reaction is it the total in both half equations?

For example:

$$\ce{2I- + Zn^2+ -> I2 + Zn}$$

First we split it up into the two half-reactions and get the following

$$\ce{2I -> I2 + 2e-}$$

$$\ce{Zn^2+ + 2e- -> Zn}$$

So would the number of electrons transferred in the redox reaction be two or four?

In the total redox reaction that is properly balanced, the number of electrons transferred is equal to the stoichiometric coefficient of the $\ce{e-}$ species in either balanced half-reaction.