<p>Cognitive Appraisal Theory (CAT) explains subjective evaluations of threats and fairness informs perceptual and behavioral responses. Value is derived through the appraisal of events. During economic fluctuations, like inflationary times, many consumers have demonstrated a willingness to accept product downsizing while being sold at the same price (i.e., shrinkflation). Certain customers are more acutely aware of exchange equity. Wherein, there presents a methodological gap in measuring these consumers across monetary and non-monetary contexts. This study psychometrically developed the exchange sensitivity scale (ESS) and how these consumers respond to shrinkflation. The ESS demonstrated satisfactory validity and reliability. Moderated mediation pathway analysis of survey data (<i>N</i> = 914) showed exchange sensitivity related to greater shrinkflation acceptance. Exchange sensitivity related to less perceived inflation (mediator) and thereby less shrinkflation acceptance. At low levels of psychological inflexibility (moderator), exchange sensitivity indirectly reduces perceived inflation which increases shrinkflation acceptance. Findings add insights to the broader perceived fairness of shrinkflation by showing how individual differences influence consumer acceptance. Theoretically, product changes should account for cognitive appraisals to retain consumer support. The ESS provides a useful tool to enhance marketing analytical models to account for this facet of consumer psychology. Future research utilizing the ESS can explore shrinkflation acceptance across different economic environments.</p>