Volume is a proxy for biomass in hard-bodied arthropods. We constructed a highly significant overall equation relating biomass and volume for Neotropical dung beetles (Scarabaeidae). In addition, we constructed separate equations for 12 Neotropical genera of scarabs, of which 11 were highly significant. In general, linear functions explained the relationship between biomass and volume equally well as log-transformed data. In addition, we tested the effects of alcohol storage on volume over the course of a year and found no significant change in dung beetle volume. Because scarab volume is not affected by alcohol storage up to a period of 1 yr, the biomass–volume equations we have provided for fresh specimens may be valid to quantify biomass of specimens stored in alcohol.