The Sequential Organ Failure Assessment (SOFA) score is a validated intensive-care tool that grades dysfunction across six organ systems — respiratory, coagulation, liver, cardiovascular, central nervous system, and renal — and sums them into a single 0-to-24 score. Introduced by Vincent and colleagues in 1996, it was designed to describe organ dysfunction objectively and to track how it evolves over an ICU stay, and it now underpins the Sepsis-3 definition of sepsis.
How the SOFA score works
Each of the six organ systems is graded from 0 (normal function) to 4 (most severe dysfunction) using a specific clinical or laboratory variable: the PaO₂/FiO₂ ratio for respiration, platelet count for coagulation, bilirubin for the liver, mean arterial pressure or vasopressor dose for the cardiovascular system, the Glasgow Coma Scale for the central nervous system, and creatinine or urine output for the kidneys. The six subscores are added together, so the total ranges from 0 to 24.
The variables were chosen to be simple, objective, and routinely available in the ICU, so the score can be computed daily from data that is already collected. Because each subscore uses the worst value in the scoring window, SOFA reflects the peak severity of organ dysfunction over that period.
Reading the score and mortality bands
Higher SOFA scores are associated with higher mortality. Using the maximum (highest) SOFA score during an ICU stay, approximate mortality is under 10% for scores of 0–6, 15–20% for 7–9, 40–50% for 10–12, 50–60% for 13–14, over 80% at 15, and over 90% for 16–24. These figures come from validation cohorts and are population averages, not predictions for any individual patient.
SOFA is most valuable as a trend. A score that climbs over the first 24–48 hours predicts worse outcomes, while a falling score suggests the patient is responding to treatment. This is why the calculator emphasizes serial scoring rather than a single reading.
Limits and how it should be used
The SOFA score describes organ dysfunction; it does not diagnose its cause, and it was not designed to guide moment-to-moment treatment decisions on its own. Its mortality estimates are statistical associations derived from specific patient populations and may not transfer precisely to every setting, comorbidity profile, or care pathway. Some subscore inputs — particularly vasopressor dosing and the choice between creatinine and urine output — require clinical judgment to apply consistently.
This calculator is for education and clinical decision support only. It supports, but never replaces, a clinician's complete assessment of the patient, and it should not be used as the sole basis for prognosis or goals-of-care decisions.