A recent morphometric model that estimates endocranial volume from 3 linear dimensions taken on the outside of the braincase has increased dramatically both the number and the taxonomic breadth of fossil and extant members of the Carnivora with endocranial volume estimates. I present a similar model for the Artiodactyla, relating volume of the endocranial cavity to braincase height, width, and length. Using Akaike information criterion–based modeling methods, I derived a set of predictive equations with respect to a recent supermatrix phylogeny of the Artiodactyla. Three distinct allometric equations are reconstructed: for Bovidae, nonbovid ruminants, and nonruminant artiodactyls. This model accurately predicted endocranial volumes for artiodactyls (R²  =  0.942), and can be used to expand the available sample of fossil and extant taxa for which endocranial volume estimates exist. This will permit reconstruction of the plesiomorphic scaling of brain volume relative to body mass and testing of hypotheses of the evolution in brain size within the artiodactyl clade and coevolutionary arms races between carnivore and ungulate communities.