Large portion sizes contribute to weight gain in western societies. Portion-size interventions, aids and education can be effective in helping prevent weight gain, but consumers are unsure what appropriate portions are and express confusion about existing guidelines. A lack of clarity about suggested serving size recommendations is a major barrier to food portion-size control. Therefore, standardised measurement units and unambiguous terminologies are required. This position paper summarises the evidence regarding the impact and importance of portion-size education and estimation, and outlines strategies for improving consumer understanding and application of this through the development of an international food measurement system and a range of appropriate portion control tools. In this position paper, the authors call for the standardisation of food volume measurement terminologies, units, implementation recommendations, as well as consumer education. The target audience for this paper includes nutrition and behavioural researchers, policy makers, and stakeholders who potentially influence and implement changes in national food measurement systems, which in turn impact on consumer choice.