Higher scores obtained using diet quality and variety indices are indicators of more optimal food and nutrient intakes and lower chronic disease risk. The aim of this paper is to describe the overall diet quality and variety in a sample of Australian adults who completed an online diet quality self-assessment tool, the Healthy Eating Quiz. The Healthy Eating Quiz takes approximately five minutes to complete online and computes user responses into a total diet quality score (out of a maximum of 73 points) and then categorizes them into the following groups: 'needs work' (<33), 'getting there' (33-38), 'excellent' (39-46), or 'outstanding' (47+). There was a total of 93,252 first-time respondents, of which 76% were female. Over 80% of respondents were between 16-44 years of age. The mean total score was 34.1 ± 9.7 points. Females had a higher total score than males ( < 0.001) and vegetarians had higher total scores than non-vegetarians ( < 0.001). Healthy eating quiz scores were higher in those aged 45-75 years compared to 16-44 years ( < 0.001). When comparing Socioeconomic Indices for Areas deciles, those most disadvantaged had a lower total score than those least disadvantaged ( < 0.001). Repeat measures showed that those who scored lowest (needs work) in their first completion increased their total score by 3.2 ± 7.4 at their second completion ( < 0.001). While the Healthy Eating Quiz data indicates that individuals receiving feedback on how to improve their score can improve their diet quality, there is a need for further nutrition promotion interventions in Australian adults.