Background: Alcohol labeling provides a relatively low-cost, population-level approach to providing information about alcohol's content and harms.

Method: We conducted an online between-subjects experiment with two tasks to examine the impact of alcohol labels (n = 1884). In one task, participants were randomized to view one of four different unit labels (including labels currently used by the alcohol industry and novel labels which provide more information about how the number of units relates to recommended drinking guidelines). We assessed participants' accuracy of estimating weekly serving limits of alcohol. In a second task, participants were randomized to view one of eight health warnings (which varied according to message content, specificity, and framing). We assessed the motivation to quit after viewing the health warning.

Results: Accuracy of estimating weekly serving limits of alcohol was greater for participants who viewed novel unit labels compared to the industry standard labels. Motivation to drink less was higher amongst participants who had viewed both cancer and negatively framed messages, compared to mental health and positively framed messages.

Conclusion: Existing unit labels used by the alcohol industry can be improved; the inclusion of unit information per serving and how these relate to low-risk drinking guidelines may be important for facilitating consumer understanding. Health warning labels should be included alongside units to provide consumers with information about the harms associated with alcohol and discourage riskier drinking behavior.