Average Propensity to Consume is the ratio between total consumption (C) and total income (Y).
APC= C / Y
Marginal Propensity to Consume (MPC) is the ratio between change in consumption ($\Delta C$) and change in income ($\Delta Y$).
MPC= $\Delta C$ / $\Delta Y$
APC can be greater than one in a situation when C>Y.