rpmodel provides an implementation of the P-model (Prentice et al., 2014; Wang et al., 2017; Stocker et al., 2019) for predicting acclimated photosynthetic parameters, assimilation, and dark respiration rates as a function of the environment. The main function is rpmodel() which returns a list of variables that are mutually consistent within the theory of the P-model. Further functions used within rpmodel() are also provided through the package.