ABSTRACT Calculation of autoecological data, such as optima and tolerance ranges to environmental variables, can be useful to establish the distribution and abundance of the species. These calculations, although mathematically not complex, can be prone to error when using a large database. We present an R package (“optimos.prime”) that uses species’ abundance data and environmental data to calculate the optimum value and tolerance range of each species to each environmental factor, by weighted average. Additionally, the package can create caterpillar plots to show the results. Using sample data from a phytoplankton database, we exemplify the use of the R package and its functions. A stand-alone version for Windows is also provided, and source code and documents are freely available on GitHub to encourage collaborative work.