Injury Severity Score Calculator

The Injury Severity Score, or ISS, summarizes the overall anatomical severity of injuries across the body. It is derived from the Abbreviated Injury Scale, a standardized system in which trained coders assign injuries scores from 1 for minor injury through 6 for currently untreatable injury. A value of 0 indicates no injury in the region. ISS is used in trauma registries, research, quality assessment, triage discussions, and comparisons of patient groups, but it does not describe every clinical priority. For ISS calculation, injuries are grouped into six regions: head and neck, face, chest, abdomen or pelvic contents, extremities or pelvic girdle, and external injuries. Enter the highest AIS score present in each region. The calculator selects the three highest regional scores, squares each one, and adds the squares. For example, regional highs of 4, 3, and 2 produce 16 plus 9 plus 4, for an ISS of 29. Multiple injuries in one region do not occupy multiple positions because only that region's highest AIS score is used. The ordinary score ranges from 1 to 75. Under the established convention, any AIS 6 injury automatically makes the ISS 75 regardless of other regional values. Broad descriptive bands are often presented as 1 to 8 minor, 9 to 15 moderate, 16 to 24 serious, 25 to 49 severe, and 50 to 75 critical. These labels are convenient summaries rather than universal treatment rules. An ISS above 15 is frequently used to identify major trauma, though protocols and study definitions can differ. ISS has important limits. It requires accurate AIS coding after injuries have been identified, so it is not a substitute for the initial airway, breathing, circulation, disability, and exposure assessment. It does not incorporate age, physiology, comorbidities, response to resuscitation, or the timing of care. Squaring emphasizes severe anatomical injuries but can underrepresent several injuries within the same region. Related systems such as the New Injury Severity Score and combined physiological models address some limitations. Use this calculator only with valid AIS codes assigned by qualified personnel, and rely on emergency and trauma specialists for real-time care and mortality assessment.