One of the challenges of international alcohol research and policy is the variability in and lack of knowledge of how governments in different nations define a standard drink and low-risk drinking. This study gathered such information from governmental agencies in 37 countries. A pool of 75 countries that might have definitions was created using World Health Organization (WHO) information and the authors' own judgement. Structured internet searches of relevant terms for each country were supplemented by efforts to contact government agencies directly and to consult with alcohol experts in the country.

Results - Most of the 75 national governments examined were not identified as having adopted a standard drink definition. Among the 37 that were so identified, the modal standard drink size was 10 g pure ethanol, but variation was wide (8–20 g). Significant variability was also evident for low-risk drinking guidelines, ranging from 10–42 g per day for women and 10–56 g per day for men to 98–140 g per week for women and 150–280 g per week for men.

Conclusions - Researchers working and communicating across national boundaries should be sensitive to the substantial variability in ‘standard’ drink definitions and low-risk drinking guidelines. The potential impact of guidelines, both in general and in specific national cases, remains an important question for public health research.