Objective The aim of the present study was to determine the potential demand for publicly and privately funded bariatric surgery in Australia. Methods Nationally representative data from the 2011-13 Australian Health Survey were used to estimate the numbers and characteristics of Australians meeting specific eligibility criteria as recommended in National Health and Medical Research Council guidelines for the management of overweight and obesity. Results Of the 3352037 adult Australians (aged 18-65 years) estimated to be obese in 2011-13, 882441 (26.3%; 95% confidence interval (CI) 23.0-29.6) were potentially eligible for bariatric surgery (accounting for 6.2% (95% CI 5.4-7.1) of the adult population aged 18-65 years (n=14122020)). Of these, 396856 (45.0%; 95% CI 40.4-49.5) had Class 3 obesity (body mass index (BMI) ≥40kgm-2), 470945 (53.4%; 95% CI 49.0-57.7) had Class 2 obesity (BMI 35-39.9kgm-2) with obesity-related comorbidities or risk factors and 14640 (1.7%; 95% CI 0.6-2.7) had Class 1 obesity (BMI 30-34.9kgm-2) with poorly controlled type 2 diabetes and increased cardiovascular risk; 458869 (52.0%; 95% CI 46.4-57.6) were female, 404594 (45.8%; 95% CI 37.3-54.4) had no private health insurance and 309983 (35.1%; 95% CI 28.8-41.4) resided outside a major city. Conclusion Even if only 5% of Australian adults estimated to be eligible for bariatric surgery sought this intervention, the demand, particularly in the public health system and outside major cities, would far outstrip current capacity. Better guidance on patient prioritisation and greater resourcing of public surgery are needed. What is known about this topic? In the period 2011-13, 4million Australian adults were estimated to be obese, with obesity disproportionately more prevalent in areas of socioeconomic disadvantage. Bariatric surgery is considered to be cost-effective and the most effective treatment for adults with obesity, but is mainly privately funded in Australia (>90%), with 16650 primary privately funded procedures performed in 2015. The extent to which the supply of bariatric surgery is falling short of demand in Australia is unknown. What does this paper add? The present study provides important information for health service planners. For the first time, population estimates and characteristics of those potentially eligible for bariatric surgery in Australia have been described based on the best available evidence, using categories that best approximate the national recommended eligibility criteria. What are the implications for practitioners? Even if only 5% of those estimated to be potentially eligible for bariatric surgery in Australia sought a surgical pathway (44122 of 882441), the potential demand, particularly in the public health system and outside major cities, would still far outstrip current capacity, underscoring the immediate need for better guidance on patient prioritisation. The findings of the present study provide a strong signal that more funding of public surgery and other effective interventions to assist this population group are necessary.