The published literature does not provide a consensus regarding maximum body sizes of North America's largest wild freshwater turtles (genus Macrochelys). The largest known wild M. suwanniensis (Suwannee Alligator Snapping Turtle) currently exists as a curated specimen measuring 713 mm straight-midline carapace length, 801 mm maximum carapace length, 619 mm maximum carapace width, and 236 mm maximum head width. The turtle was never weighed, but we used morphometric data from our studies in the Santa Fe and Suwannee rivers to estimate that it weighed ∼76.4 kg (168 lbs) when captured. Our 95% prediction interval (67.6–86.3 kg [149–190 lbs]) suggests that speculative estimates and anecdotal reports of M. suwanniensis that weigh ≥90 kg (≥200 lbs) are dubious.