Introduction Although the costs for people with haemophilia A (PwHA) in Europe and the United States have been well characterized, to date, there are no cost estimates for PwHA in Australia. The purpose of this study was to estimate direct and indirect costs of moderate and severe haemophilia A (HA) in Australia under current treatment practices. Methods The number of Australian males with moderate or severe HA was projected from Australian Bleeding Disorders Registry (ABDR) data. We estimated the prevalence in 2018 of adults with moderate HA to be 159 people, severe to be 416; and 68 and 283, respectively, in the paediatric (aged < 18 years) population. We used a ‘bottom‐up prevalence based cost of illness approach’ to estimate costs; that is, we estimated the per capita cost for different groups of PwHA; for example, by age and disease severity, and these per capita costs were scaled up to the estimated population with HA. Costs were estimated based on publicly available secondary data and literature review. Results The treatment‐related costs, direct and indirect costs, of moderate to severe HA are significant, totalling over AUD$111M in 2018, equating to a yearly per patient cost of approximately AUD$120 000 (equivalent to ~EUR€74 000 or ~USD$85 000). Conclusion Although HA affects a relatively small number of people within the Australian population, it is associated with high aggregate costs and imposes a high economic burden.