Sofa Score Calculator
Calculate Sequential Organ Failure Assessment score for sepsis and organ dysfunction. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateSepsis-3 Interpretation
SOFA < 2 does not meet Sepsis-3 organ dysfunction threshold.
SOFA Mortality Scale
Formula
Six organ systems are each scored 0-4 based on degree of dysfunction. Total score ranges from 0 to 24. Higher scores indicate greater organ dysfunction and higher ICU mortality. SOFA ≥2 with suspected infection meets the Sepsis-3 definition of sepsis.
Last reviewed: January 2026
Worked Examples
Example 1: Mild Organ Dysfunction
Example 2: Severe Multi-Organ Failure
Background & Theory
The Sofa Score Calculator applies the following established principles and formulas. Health and medicine calculators are grounded in validated physiological measurement methods established through decades of clinical research. Body Mass Index, or BMI, is calculated by dividing weight in kilograms by height in meters squared (kg/m²), a formula originating from Adolphe Quetelet's 19th-century statistical work and later codified by the WHO into standard classifications: underweight below 18.5, normal weight 18.5 to 24.9, overweight 25 to 29.9, and obese at 30 and above. Basal Metabolic Rate quantifies the minimum energy required to sustain life at rest. The Mifflin-St Jeor equation, published in 1990 and widely regarded as the most accurate for most adults, calculates BMR as (10 × weight in kg) + (6.25 × height in cm) − (5 × age) ± sex adjustment. The older Harris-Benedict equations, revised in 1984 by Roza and Shizgal, remain in common use. Total Daily Energy Expenditure is derived by multiplying BMR by a physical activity factor ranging from 1.2 for sedentary individuals to 1.9 for extremely active ones, following the methodology validated by doubly labeled water studies. Body fat percentage can be estimated without laboratory equipment using the U.S. Navy circumference method, which uses neck, waist, and hip measurements, or via BMI-derived equations adjusted for age and sex. The Jackson-Pollock skinfold method offers higher precision with calipers. Blood pressure classification, according to the American College of Cardiology and the 2017 ACC/AHA guidelines, defines normal as below 120/80 mmHg, elevated as 120 to 129 systolic, and hypertension stage 1 as 130 to 139 systolic or 80 to 89 diastolic. Target heart rate zones for aerobic exercise are derived from maximum heart rate estimates, most commonly using the formula 220 minus age in years, with moderate-intensity training typically defined as 50 to 70 percent of maximum heart rate and vigorous intensity at 70 to 85 percent, consistent with CDC and American Heart Association guidelines. These thresholds guide safe and effective cardiovascular conditioning.
History
The history behind the Sofa Score Calculator traces back through the following developments. The history of health measurement stretches back to ancient Greece, where Hippocrates around 400 BCE laid the foundation for observational medicine by systematically recording patient symptoms, diet, and environment. His humoral theory, though scientifically superseded, established the principle that the body operates as an interconnected system subject to measurable imbalance. The transformation toward modern medicine accelerated in the 19th century. Louis Pasteur and Robert Koch developed germ theory in the 1860s and 1870s, identifying microorganisms as disease agents and enabling targeted interventions. Florence Nightingale, working during the Crimean War in the 1850s, introduced statistical analysis to nursing practice, demonstrating through data visualization that sanitation reduced mortality. Her work is foundational to evidence-based health measurement. The discovery of vitamins in the early 20th century, beginning with Casimir Funk's coinage of the term in 1912 and culminating in the isolation of vitamins A through K, created the field of nutritional science and gave rise to dietary reference intake frameworks. The World Health Organization, founded in 1948, subsequently established global standards for health metrics, disease classification through the International Classification of Diseases, and recommended daily allowances. The BMI as a clinical screening tool gained traction in the 1970s through Ancel Keys' large-scale epidemiological work, which validated Quetelet's index as a population-level obesity indicator. Through the 1980s and 1990s, the Framingham Heart Study produced landmark data linking cholesterol, blood pressure, and lifestyle factors to cardiovascular disease risk, directly shaping the numeric thresholds still used in health calculators. The evidence-based medicine movement, formalized by Gordon Guyatt and colleagues at McMaster University in the early 1990s, demanded that all health recommendations derive from systematically graded clinical evidence. The digital health era beginning in the 2000s brought these formulas to consumer devices, wearable sensors, and smartphone applications, expanding access to health self-monitoring on a global scale and enabling population-level data collection that continues to refine clinical reference ranges.
Frequently Asked Questions
Sources & References
Formula
SOFA = Respiration(0-4) + Coagulation(0-4) + Liver(0-4) + Cardiovascular(0-4) + CNS(0-4) + Renal(0-4)
Six organ systems are each scored 0-4 based on degree of dysfunction. Total score ranges from 0 to 24. Higher scores indicate greater organ dysfunction and higher ICU mortality. SOFA ≥2 with suspected infection meets the Sepsis-3 definition of sepsis.
Worked Examples
Example 1: Mild Organ Dysfunction
Problem: ICU patient with mild hypoxia (PaO2/FiO2 350), slightly low platelets (130k), alert, normal BP, normal renal function.
Solution: Respiration: 1 (PaO2/FiO2 301-400)\nCoagulation: 1 (Platelets 100-149)\nLiver: 0\nCardiovascular: 0\nCNS: 0\nRenal: 0\nTotal SOFA = 2\nMortality: ~3-5%
Result: SOFA 2 — Low-Moderate severity, meets Sepsis-3 threshold if infection present
Example 2: Severe Multi-Organ Failure
Problem: Septic shock patient: PaO2/FiO2 80 on ventilator, platelets 18k, bilirubin 8.5, on norepinephrine 0.3, GCS 7, creatinine 4.2.
Solution: Respiration: 4\nCoagulation: 4\nLiver: 3\nCardiovascular: 4\nCNS: 3\nRenal: 3\nTotal SOFA = 21\nMortality: >80%
Result: SOFA 21 — Critical, multi-organ failure with very high mortality
Frequently Asked Questions
What is the SOFA score?
The Sequential Organ Failure Assessment (SOFA) score is used to track a patient's status in the ICU by assessing the extent of organ dysfunction across six organ systems: respiratory, coagulation, liver, cardiovascular, central nervous system, and renal. Each system is scored 0-4, giving a total range of 0-24. Higher scores indicate greater organ dysfunction and higher mortality risk. It is also a key component of the Sepsis-3 definition.
How does SOFA relate to sepsis diagnosis?
Under the Sepsis-3 definition (2016), sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Organ dysfunction is identified as an acute change in total SOFA score ≥2 points consequent to the infection. A SOFA score ≥2 in the setting of suspected infection has a mortality of approximately 10% or greater.
What is the qSOFA score?
The quick SOFA (qSOFA) is a bedside screening tool using three criteria: altered mental status (GCS <15), systolic BP ≤100 mmHg, and respiratory rate ≥22. Two or more qSOFA points should prompt further assessment for organ dysfunction (full SOFA score), increased monitoring, and consideration of infection. qSOFA is not a diagnostic tool but a screening prompt.
How often should SOFA be calculated?
SOFA should be calculated at ICU admission and then every 24-48 hours to track organ dysfunction trends. The change in SOFA (delta-SOFA) over time is more predictive of outcome than a single measurement. An increasing SOFA score suggests worsening organ dysfunction and carries a worse prognosis, while a decreasing score suggests recovery.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
Why might my result differ from another tool or reference?
Differences typically arise from rounding conventions, the specific version of a formula (for example, simple vs compound interest), or unit inconsistencies between inputs. Check that both tools are using the same formula variant and the same units. The References section links to the authoritative source behind the formula used here.
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy