In this work the effect of sub-500nm patterning on exchange bias in thin films has been studied. The experimental results are compared to a theoretical model in which the York Model of Exchange Bias has been modified to take into account grain cutting at the edges of the structures. Exchange bias (Hex) was found to decrease with element size. The form of the variation of Hex with element size matches that of the experiment. Numerical agreement has not been achieved for Hex. However the predictions of the median blocking temperature <Tb> agree with experiment. The disagreement between the experiment and the theory for Hex is attributed to edge roughness of the structures which is not taken into account by the model. This edge roughness will affect the quality of the interface which is dominant in structures of this scale.