In this study, we determined how well the snout–vent length (SVL) of anurans estimated their mass for 36 species in the New World. Linear regressions of log-mass on log-SVL were highly significant for all species, explaining more than 75% of the mass variation in most species, and over 50% of the mass variation in all species. We also investigated differences in the mass/SVL relationship within species, comparing juveniles to adults, females to gravid females, and males to females, to determine the importance of developing separate regressions for sex or life-stage classes. Three of six tests between juveniles and adults, and two of nine tests between females and gravid females, indicated statistically significant differences, although these differences had only minor effects on mass estimates. More statistical differences in regression equations occurred between males and females; again, these differences were unimportant for estimates of mass in some cases, but they were important where there was strong sexual size dimorphism within a species. Continued collection of both SVL and mass data in new field studies of anurans will provide broader analyses of mass/SVL regressions. These species regressions along with data on density can be used to determine anuran community biomass.