In both an increasingly digital and aging society, natural age-related cognitive changes take place, which may negatively affect performance when using increasingly complex digital interfaces. Obtaining daily needs such as groceries becomes more difficult with age and shopping for groceries online presents a challenge to many older adults. The purpose of this study is to understand how and in what ways age affects online grocery shopping performance. 32 participants were recruited for this study consisting of 17 younger adults and 15 older adults. Participants were presented with sets of tasks which required them to mentally calculate the quantity of food they can purchase within a given budget. Eye tracking and survey methods were used during the study. Our results show that age negatively impacts cognitive load. Cognitive load was found to negatively impact performance in online grocery shopping tasks. Self-efficacy showed to have a mild moderating effect on said relationship.