SOFA Score Calculator
Calculate the SOFA score from PaO₂/FiO₂, platelets, bilirubin, blood pressure support, GCS, creatinine and urine output. Enter your lab values and vasopressor category to get the total and per-organ breakdown.
Score the Six Organ Systems of the Sequential Organ Failure Assessment
SOFA Score Formula
Where:
- \(R\) — respiration score, based on the PaO₂/FiO₂ ratio (mmHg)
- \(C\) — coagulation score, based on the platelet count (×10³/µL)
- \(L\) — liver score, based on total bilirubin (mg/dL)
- \(\text{CV}\) — cardiovascular score, based on mean arterial pressure and vasopressor doses
- \(\text{CNS}\) — central nervous system score, based on the Glasgow Coma Scale
- \(K\) — renal score, based on creatinine (mg/dL) or urine output, whichever is worse
Each organ system is graded from 0 (normal function) to 4 (severe failure), so the total SOFA score ranges from 0 to 24 points. Higher totals indicate more severe organ dysfunction.
The grading thresholds are:
- Respiration (PaO₂/FiO₂, mmHg): ≥400 = 0; <400 = 1; <300 = 2; <200 with respiratory support = 3; <100 with respiratory support = 4
- Coagulation (platelets ×10³/µL): ≥150 = 0; <150 = 1; <100 = 2; <50 = 3; <20 = 4
- Liver (bilirubin, mg/dL): <1.2 = 0; 1.2–1.9 = 1; 2.0–5.9 = 2; 6.0–11.9 = 3; ≥12.0 = 4
- Cardiovascular: MAP ≥70 mmHg without vasopressors = 0; MAP <70 mmHg = 1; dopamine ≤5 or dobutamine (any dose) = 2; dopamine >5, epinephrine ≤0.1 or norepinephrine ≤0.1 µg/kg/min = 3; dopamine >15, epinephrine >0.1 or norepinephrine >0.1 µg/kg/min = 4
- CNS (Glasgow Coma Scale): 15 = 0; 13–14 = 1; 10–12 = 2; 6–9 = 3; <6 = 4
- Renal (creatinine, mg/dL, or urine output): <1.2 = 0; 1.2–1.9 = 1; 2.0–3.4 = 2; 3.5–4.9 or urine output <500 mL/day = 3; ≥5.0 or urine output <200 mL/day = 4
SOFA Score – Calculation Example
Example: an ICU patient on non-invasive respiratory support with FiO₂ 40% has a PaO₂ of 120 mmHg. Platelets are 95 ×10³/µL, total bilirubin 2.5 mg/dL, creatinine 2.2 mg/dL, urine output ≥500 mL/day, and GCS 13. The patient receives norepinephrine at 0.08 µg/kg/min.
\[ \text{PaO}_2/\text{FiO}_2 = 120 / 0.40 = 300 \implies R = 1 \]
\[ \text{PLT} = 95 \implies C = 2, \quad \text{Bili} = 2.5 \implies L = 2 \]
\[ \text{norepinephrine} \le 0.1 \implies \text{CV} = 3, \quad \text{GCS} = 13 \implies \text{CNS} = 1 \]
\[ \text{Cr} = 2.2 \implies K = 2 \]
\[ \text{SOFA} = 1 + 2 + 2 + 3 + 1 + 2 = 11 \]
Result: SOFA score = 11 of 24 points, with reported in-hospital mortality of roughly 40–50% in this range.
How to use the calculator
- Enter the Arterial PaO₂ value and select mmHg or kPa as the unit; the value is converted automatically.
- Enter the Inspired oxygen (FiO₂) as a percentage (room air = 21). A value between 0 and 1, such as 0.4, is read as a fraction.
- Tick Mechanical ventilation / respiratory support if the patient receives any form of respiratory support. SOFA grades 3–4 for respiration formally require it.
- Enter the Platelet count in ×10³/µL (e.g. 95 for 95,000/µL).
- Enter the Total bilirubin and choose mg/dL or µmol/L.
- Select the matching option under Blood pressure support / vasopressors, based on the mean arterial pressure and vasopressor doses in µg/kg/min.
- Enter the Glasgow Coma Scale (3–15). If you need help scoring it, see our Glasgow Coma Scale calculator.
- Enter the Creatinine value with its unit, and select the Urine output category. The renal score is the worse of the two criteria.
The results panel shows each organ subscore, the total SOFA score, and an interpretation with the PaO₂/FiO₂ ratio and converted values actually used.
What is the SOFA score?
The Sequential Organ Failure Assessment (SOFA) score quantifies the severity of organ dysfunction in critically ill patients across six systems: respiration, coagulation, liver, cardiovascular, central nervous system and kidneys. It was introduced by Vincent et al. in 1996 to describe morbidity in ICU populations in a reproducible, repeatable way, using simple bedside measurements and routine lab values.
Each organ is scored 0–4, giving a total of 0–24 points. A score of 0 means normal organ function; higher subscores indicate progressively severe failure of that organ. The total is most informative when tracked over time: a rising SOFA score suggests worsening organ dysfunction, while a falling score suggests recovery. In ICU studies, in-hospital mortality rises from under 10% at scores of 0–6, to roughly 15–20% at 7–9, 40–50% at 10–12, and above 50% beyond 12 points.
The SOFA score is also central to the modern definition of sepsis. Under the Sepsis-3 criteria (2016), a suspected infection together with an acute increase of 2 or more SOFA points from baseline indicates sepsis, and septic shock is defined by vasopressor requirements plus a lactate above 2 mmol/L despite adequate fluid resuscitation. For rapid bedside screening outside the ICU, the qSOFA score uses only three of the SOFA components; the older SIRS criteria remain an alternative screening trigger.
Limitations and practical tips
- The SOFA score was designed for ICU patients. Applied to general ward populations, it can underestimate risk because many patients never develop measurable organ dysfunction there.
- The score describes current organ function, not prognosis for an individual. The mortality figures attached to score ranges are population averages from observational studies, not personal predictions.
- For sepsis diagnosis, the change from the patient's baseline (ΔSOFA) matters more than a single absolute value. If no baseline is known, community patients are often assumed to have a baseline of 0.
- The renal subscore takes the worse of the creatinine and urine output criteria, so a low urine output can raise it even when creatinine is only mildly elevated.
- Respiratory grades 3–4 formally require respiratory support (mechanical ventilation or non-invasive ventilation); the calculator adds a note when your PaO₂/FiO₂ falls below 200 without support flagged.
- Values entered in kPa or µmol/L are converted to mmHg and mg/dL internally using standard factors (1 kPa = 7.50062 mmHg; bilirubin µmol/L ÷ 17.104; creatinine µmol/L ÷ 88.4).
- Related tools: for liver-specific severity in cirrhosis see the Child-Pugh score, and for renal function assessment the eGFR calculator (CKD-EPI 2021).
- This calculator is for information only and does not replace clinical judgment or a medical diagnosis.
Frequently Asked Questions
How do I calculate the SOFA score by hand?
Score each of the six organ systems from 0 to 4 using the PaO₂/FiO₂ ratio, platelet count, bilirubin, vasopressor support, Glasgow Coma Scale, and creatinine or urine output — then add the six subscores together. For example, PaO₂/FiO₂ of 250 mmHg scores 2, platelets of 40 ×10³/µL score 3, and so on. The total ranges from 0 to 24. Scoring by hand takes a few minutes once you know the thresholds; the calculator mainly helps avoid mistakes at the grade boundaries.
What is a normal or good SOFA score?
A total of 0 means all six organ systems are functioning normally, and scores up to about 6 are generally considered mild dysfunction with low associated in-hospital mortality (under 10% in ICU studies). Scores of 7–9 indicate moderate dysfunction, and 10 or more points suggest severe multi-organ involvement. Keep in mind these are population averages from observational studies, not predictions for an individual patient, and the trend over time usually matters more than one value.
How do I convert PaO₂ from kPa to mmHg and bilirubin or creatinine from µmol/L to mg/dL?
Multiply kPa by 7.50062 to get mmHg, so a PaO₂ of 10 kPa equals 75 mmHg. For bilirubin, divide µmol/L by 17.104 to get mg/dL (34 µmol/L ≈ 2.0 mg/dL). For creatinine, divide µmol/L by 88.4 (177 µmol/L ≈ 2.0 mg/dL). The calculator performs these conversions automatically when you select kPa or µmol/L as the unit, so you can enter lab report values directly.
Can I use the SOFA score for patients outside the ICU?
The SOFA score was designed and validated for ICU populations, so it can underestimate risk on general wards, where many patients never develop measurable organ dysfunction despite being seriously ill. For quick bedside screening outside the ICU, qSOFA (respiratory rate ≥22/min, systolic BP ≤100 mmHg, altered mentation) is a simpler alternative, though Sepsis-3 no longer recommends it as a standalone tool. Clinical judgment should always supplement any score.
What is the difference between SOFA, qSOFA and SIRS?
SOFA is the full six-organ assessment used to quantify organ dysfunction and, under Sepsis-3, to define sepsis (an acute rise of ≥2 points with suspected infection). qSOFA is a rapid three-variable screen — breathing rate, blood pressure and mental status — that needs no labs but is less sensitive. SIRS criteria (temperature, heart rate, respiratory rate, white blood cells) are older and more sensitive but less specific. They serve different purposes: screening versus formal assessment.
Why does the renal score use both creatinine and urine output?
The original SOFA definition scores the kidneys by whichever criterion is worse. A patient with modestly elevated creatinine (say 1.5 mg/dL, worth 1 point) but urine output under 200 mL/day receives 4 points, because oliguria signals more severe renal failure than the creatinine alone suggests. In the calculator, select the urine-output category that matches the patient; if urine output was not measured, choose the 'not measured' option and the score relies on creatinine alone.
What are common mistakes when scoring SOFA?
Frequent errors include forgetting to tick respiratory support for PaO₂/FiO₂ below 200 (grades 3–4 formally require it), entering FiO₂ incorrectly (0.4 versus 40), using sedation-adjusted rather than best-observed GCS, ignoring a low urine output that should raise the renal score, and applying the score to ward patients where it underestimates risk. Also remember that for sepsis diagnosis the change from baseline (ΔSOFA) matters, not a single absolute value — assume a baseline of 0 if unknown.