The efficacy of OPC models depends on the ability to determine the physical dimensions of a large variety of photoresist patterns. This ability is impacted by a long observed phenomenon, photoresist shrinkage during CD-SEM metrology. As technology dimensions have scaled, the ability to directly measure the photoresist physical dimensions have diminished, while the need to reduce sources of uncertainty and error have increased. It has therefore become imperative to find other techniques to characterize this effect. In this paper, we compare methods of characterizing photoresist shrinkage of patterns using both etch-based and metrology-based approaches.