Objective Long-acting reversible contraception (LARC) is the most effective form of reversible contraception, but its use in Australia is low compared with other countries. The aim of this study was to evaluate the economic effect of an increase in LARC uptake to international rates. Methods An economic model was designed to assess two scenarios, namely increasing the current rate of LARC uptake of 12.5% to the international benchmark of 14.8% among: (1) women currently using the oral contraceptive pill (OCP); and (2) women at risk of pregnancy and not using contraception. Model inputs included cost of contraceptive methods, discontinuation rates and abortion and miscarriage costs associated with unintended pregnancies. Results Women who switch from an OCP to LARC would save A$114-157 per year. Those not currently using any contraception who adopt LARC would incur costs of A$36-194 per year, but would reap savings from the reduction in unintended pregnancies. Over 5 years there would be a net saving of A$74.4 million for Scenario 1 and A$2.4 million for Scenario 2. Conclusion Greater use of LARC would result in a net gain in economic benefits to Australia. These benefits are largely driven by women switching from an OCP to LARC who have reduced costs, as well as women wishing to avoid pregnancy who choose to use LARC rather than no method. This evidence will support women making an informed contraceptive choice and policy makers in increasing the accessibility of LARC. What is known about the topic? LARC is the most effective form of reversible contraception, but uptake in Australia is relatively low. What does this paper add? There are economic benefits to society for women who switch from an OCP to LARC, as well as for women who switch from no contraception to LARC. What are the implications for practitioners? The findings of this study will support women in making an informed contraceptive choice and policy makers in increasing the accessibility of LARC.