Approximately 2000 species and ecological communities are listed as threatened in Australia. Significant adverse impacts on these can trigger the requirement to offset those impacts. Best practice offsetting requires that both the losses and the expected gains for those biodiversity features must be measured, to ensure that impacts are fully counterbalanced. The units, or currency, in which they are measured must therefore be direct measures, or effective proxies, for the biodiversity features in question. Different currencies are suitable for use in calculations of impacts and benefits (losses and gains) for different species – for some, area x habitat condition indices are suitable proxies for benefit to a species; for others, population size or density may be a more appropriate and direct way to measure losses and gains. Here, we develop a framework for determining which types of currencies are most appropriate for measuring losses and gains in an offsets context.