AbstractResearch shows that features of food packaging can help to promote healthy food choices. Laboratory‐based studies demonstrate that smart design of packaging facilitates portion control. However, the extent to which consumers notice packaging features for portion control is not known. Therefore, this study investigated how individuals interact with food packaging, how they utilise the on‐pack serving‐size guidelines and how they make portion decisions. To do this, 25 adult participants were recruited to participate in an online semi‐structured interview. Data were analysed using thematic analysis until saturation was achieved. Participants reported that they rarely attend to on‐pack serving recommendations and indicated some resistance to them. Some structural features (small/single serving, pre‐portioned and resealable packaging) were identified as facilitators of portion control. In contrast, the healthiness evaluation of the product from packaging cues was described as a permissive cue to eat more of the product. Participants in this study value their autonomy and control, preferring convenient behavioural choices over recommended portion servings. They also reported future concerns about the effects of their diet on health, but that current context (hunger, convenience) sometimes presented a barrier to healthy eating. Packaging does more than protect its contents, packaging can affect eating decisions to support portion control, and for some, offers permission to overconsume. This study identified ways that participants use packaging to make portion decisions, revealing the role of habits, current context and future health considerations. The interviews revealed the importance of consumer values on food choice in general and portion control in particular. In conclusion, smart food packaging design could use these findings to nudge healthy portion decisions by incorporating consumer values and by recognising consumer needs for habitual, current and future concerns.