SOFA Score Calculator (Sequential Organ Failure Assessment)
The SOFA (Sequential Organ Failure Assessment) score quantifies the degree of organ dysfunction across six systems in critically ill patients. Each system is scored 0 to 4, giving a total of 0 to 24. Higher scores correlate with greater organ failure and higher ICU mortality. Enter the worst values recorded within the past 24 hours to get the total score, an estimated mortality risk, and a breakdown by organ system.
What is the SOFA score?
The Sequential Organ Failure Assessment (SOFA) score was developed by Jean-Louis Vincent and colleagues in 1996, originally called the Sepsis-related Organ Failure Assessment. It quantifies the degree of organ dysfunction across six systems: respiratory, coagulation, hepatic, cardiovascular, neurological (central nervous system), and renal. Each system is scored on a 0 to 4 scale using readily available bedside and laboratory values, giving a total score of 0 to 24. The SOFA score is used routinely in intensive care units worldwide to describe organ failure severity, track patient trajectory, and estimate prognosis. It was also incorporated into the 2016 Sepsis-3 consensus definitions, where an acute increase in SOFA score of 2 or more points from baseline is used to identify organ dysfunction attributable to suspected infection.
How each organ system is scored
Respiratory function is assessed using the PaO2/FiO2 (P/F) ratio: a ratio above 400 mmHg scores 0, while 100 mmHg or below with ventilatory support scores 4. Coagulation uses platelet count: 150 x10^3/uL or above scores 0; below 20 scores 4. Liver function uses total bilirubin: below 1.2 mg/dL scores 0; 12 mg/dL or above scores 4. Cardiovascular status combines mean arterial pressure and vasopressor requirements: MAP at or above 70 mmHg without vasopressors scores 0, while high-dose vasopressor requirements score 4. Neurological status uses the Glasgow Coma Scale: a GCS of 15 scores 0; below 6 scores 4. Renal function uses serum creatinine or urine output: creatinine below 1.2 mg/dL scores 0; creatinine at or above 5.0 mg/dL or urine output below 200 mL per day scores 4. Clinicians use the worst value recorded in each 24-hour period.
Serial SOFA scoring and clinical trajectory
A single SOFA value is informative, but serial measurements reveal more about prognosis and treatment response. Data from prospective ICU studies show that patients whose SOFA score increases over the first 48 hours of ICU admission face mortality rates above 50%. Those with an unchanged score face mortality of roughly 27-35%, and those with a decreasing score have mortality below 27%. This is why many guidelines and protocols recommend recalculating SOFA every 24 to 48 hours rather than relying on a single admission value. The delta SOFA (change from baseline) is also used to define the presence of sepsis-associated organ dysfunction under the Sepsis-3 criteria.
SOFA, qSOFA, and Sepsis-3
The 2016 Sepsis-3 task force introduced two scoring tools alongside the new sepsis definition. The full SOFA score requires laboratory values and is designed for ICU use. The quick SOFA (qSOFA) is a simplified bedside screen using only respiratory rate, altered mentation, and systolic blood pressure - it can be applied outside the ICU without labs. A qSOFA score of 2 or more should prompt consideration of organ dysfunction and potential sepsis. However, SOFA remains the primary tool for confirming organ dysfunction in suspected sepsis: an acute increase in SOFA of 2 or more points over baseline in a patient with suspected infection meets the Sepsis-3 definition of sepsis. Septic shock is identified when sepsis is present and vasopressors are needed to maintain MAP at or above 65 mmHg alongside a serum lactate above 2 mmol/L despite adequate fluid resuscitation.
SOFA Score: Mortality Risk Stratification
| SOFA Score | Estimated ICU Mortality | Risk Level |
|---|---|---|
| 0-6 | <10% | Low |
| 7-9 | 15-20% | Moderate |
| 10-12 | 40-50% | High |
| 13-14 | 50-60% | Very High |
| 15-24 | >80% | Severe |
Approximate ICU mortality rates by maximum SOFA score. Based on Vincent et al. (1996) and Ferreira et al. (2001). Values represent population-level risk and should not replace clinical judgment.
Frequently asked questions
What SOFA score indicates sepsis?
Under the Sepsis-3 definition (2016), sepsis is identified when a patient with suspected infection has an acute increase in total SOFA score of 2 or more points from their baseline. Since most patients without pre-existing organ dysfunction have a baseline SOFA of 0, a score of 2 or more on presentation is commonly used as the threshold. A score of 2 corresponds to an estimated mortality risk of approximately 10%, which the task force used to define clinically significant organ dysfunction.
What is the difference between SOFA and qSOFA?
SOFA requires laboratory values (PaO2, platelets, bilirubin, creatinine) and is best suited to ICU and monitored settings. qSOFA (quick SOFA) is a three-variable bedside screen - altered mental status, respiratory rate 22 breaths/min or above, and systolic blood pressure 100 mmHg or below - that can be applied anywhere without labs. qSOFA is used to quickly flag patients outside the ICU who may have sepsis, while SOFA is used to confirm and quantify organ dysfunction once a patient is being closely monitored.
Can the SOFA score predict mortality accurately for an individual patient?
No. The mortality percentages associated with SOFA scores are population-level estimates derived from large ICU cohort studies. They describe what happened to groups of patients with similar scores, not what will happen to any specific individual. A patient with a SOFA of 12 does not have a 45% personal probability of dying - the actual outcome depends on the underlying diagnosis, the speed and quality of treatment, comorbidities, and many other factors. SOFA should be interpreted alongside the full clinical picture, not used as a standalone mortality prediction.
Which values should I use - the worst or the current?
Always use the worst value recorded for each organ system within the preceding 24-hour period. For example, if a patient's creatinine peaked at 3.0 mg/dL during the day but is now 2.5 mg/dL, you use 3.0 for the renal sub-score. This convention ensures that the score captures the maximum degree of dysfunction experienced, which is the value validated in the original prognostic studies.
How do I score the cardiovascular component if a patient is on multiple vasopressors?
Use the agent requiring the highest dose category. Dopamine above 15 mcg/kg/min, epinephrine above 0.1 mcg/kg/min, or norepinephrine above 0.1 mcg/kg/min each score 4 - the maximum. If a patient is on a combination, select the category that best reflects the overall vasopressor burden. Dobutamine at any dose scores 2 alongside dopamine at or below 5 mcg/kg/min.
Does SOFA apply outside the ICU?
SOFA was validated primarily in ICU populations and its mortality estimates are derived from those settings. Outside the ICU, the score may still be calculated, but the mortality thresholds may not apply with the same accuracy. For ward or emergency department screening, qSOFA is typically preferred as a rapid initial tool. A patient with a high qSOFA should be evaluated for sepsis and may warrant urgent ICU review, at which point full SOFA scoring becomes appropriate.