A key element for diagnosing cardiac enlargement in an autopsy setting is relevant heart weight references. However, most available references are to a large extent not representative of a medicolegal autopsy population, implying that reference weights are likely lower than those in the relevant population.To establish more applicable heart weight references in a medicolegal autopsy population, we designed a heart weight model that accounts for undiagnosed cardiac enlargement using data from 11,897 nontraumatic Swedish medicolegal autopsy cases autopsied between 2010 and 2019. The model was validated in 296 nonobese young adult suicidal hanging cases.For a decedent of average height (174 cm), the evidence that a heart weight was enlarged reached weak support at approximately 430 g, substantial support at approximately 480 g, and strong support at 520 g. The modeled prevalence of cardiac enlargement was very high among elderly and obese decedents.We believe that our model is more applicable in a medicolegal setting than those previously published. The presented quantification of the degree of uncertainty regarding diagnosis can help the pathologist in diagnosing cardiac enlargement. To facilitate the use of this model, we also made it available through a simple online tool (https://formedum.shinyapps.io/HeartWeightCalc/).