SOFA Score Calculator

A SOFA score of 2 is not automatically sepsis

The original Sequential Organ Failure Assessment describes dysfunction across six organ systems. It does not identify the organism causing an infection or establish why an organ is impaired. The Sepsis-3 definition ties an acute increase of at least 2 points to infection and the clinical assessment of organ dysfunction. Chronic abnormalities must be considered when determining the baseline. The consensus definition and original criteria appear together in Sepsis-3 [1].

Consider three hypothetical assessments with a current total of 5. Against baseline 0, the change is +5; against baseline 3, it is +2; against baseline 5, it is 0. The current organ scores are identical, but the acute-change statements differ. A baseline chosen merely because it produces a two-point increase reverses the reasoning: the baseline must come from the clinical history and an appropriate assessment period.

The same distinction applies to serial monitoring. Moving from 9 yesterday to 7 today gives a daily change of −2. If the established pre-illness baseline was 0, the current difference from that baseline is still +7. Write down which comparison you mean. A falling total also does not tell you which organ improved unless you retain the individual subscores.

Six systems, five scoring bands

Each system contributes an integer from 0 to 4, making 24 the maximum total. These are scoring bands, not stand-alone laboratory reference intervals or treatment targets. The table below expresses the original criteria as continuous intervals so a value with more decimal places cannot fall into a gap between printed bands.

*Without qualifying respiratory support, a P/F ratio below 200 remains in the 2-point band. Vasoactive doses are positive infusion rates in µg/kg/min, sustained for at least one hour; choose the highest applicable category. The renal score uses the higher criterion, never their sum. Sources: original SOFA and Sepsis-3 [1, 2].

At exact boundaries, platelet counts of 150, 100, 50 and 20 receive 0, 1, 2 and 3 points respectively. Urine output of exactly 500 mL does not meet the below-500 criterion; exactly 200 meets the below-500 criterion but not below-200. Those distinctions can change the final total by one point without any change elsewhere.

Follow the numbers: a total of 9

The prefilled example is invented for checking the arithmetic. It uses PaO₂ 80 mmHg, FiO₂ 50%, qualifying respiratory support, platelets 90 ×10⁹/L, bilirubin 1.5 mg/dL, MAP 65 mmHg without a qualifying vasoactive infusion, GCS 14, creatinine 1.6 mg/dL and urine output 800 mL/24 h. Assume that these are the appropriate observations from the same window.

1. Respiration: 80 ÷ 0.50 = 160 mmHg. With support, that contributes 3.
2. Coagulation: platelets 90 sit between 50 and 100, contributing 2.
3. Liver: bilirubin 1.5 sits between 1.2 and 2, contributing 1.
4. Cardiovascular: MAP 65 is below 70 without a qualifying infusion, contributing 1.
5. Central nervous system: GCS 14 contributes 1.
6. Renal: creatinine contributes 1; urine output contributes 0. The higher value is 1.

The total is 3 + 2 + 1 + 1 + 1 + 1 = 9/24. If urine output changes to 400 mL/24 h, the renal score rises from 1 to 3 and the total becomes 11. If instead platelets change from 90 to 100, the coagulation score falls from 2 to 1 and the total becomes 8. These are changes in scoring bands, not estimates of how treatment will change survival.

Two very different patterns can total 4: one system scoring 4 and five scoring 0, or four systems scoring 1 and two scoring 0. Keeping the organ breakdown avoids treating those patterns as interchangeable clinical descriptions. A total compresses information; the component scores preserve where the points came from.

Why 50% oxygen must become 0.50

FiO₂ is a fraction in the P/F equation. Dividing 80 by 50 gives 1.6, whereas dividing 80 by 0.50 gives the intended result, 160 mmHg. The percentage input above performs that conversion explicitly. A pulse-oximeter reading such as SpO₂ 96% is a different measurement and cannot replace an arterial oxygen pressure.

Pair PaO₂ with the FiO₂ at the time the blood sample was obtained. With PaO₂ held at 80, a fraction of 0.40 gives a ratio of 200, while 0.50 gives 160. Under the original criteria, with respiratory support, those ratios score 2 and 3 respectively. Combining a morning blood gas with an unrelated afternoon oxygen setting manufactures a ratio that was never measured.

Do not infer the support flag from the P/F ratio itself. A ratio of 90 with qualifying support contributes 4, while the same ratio without it contributes 2 under the original rules. Neither result makes that oxygenation measurement reassuring. Definitions for newer support modalities must be settled by the applicable clinical or research protocol, rather than silently guessed by a calculator.

Use the higher renal criterion; check support separately

Creatinine and urine output both describe the renal component, so they compete for one slot. Creatinine 1.6 mg/dL and urine output 400 mL/24 h produce max(1, 3) = 3, not 4. Creatinine 5 mg/dL and urine output 100 mL/24 h produce max(4, 4) = 4, not 8. The overall total cannot exceed 24.

Use measured urine volume over a complete 24-hour interval. An hourly rate of 40 mL/h would total 960 mL only if that rate persisted for all 24 hours; entering the number 40 in a daily-volume field instead selects the most severe urine-output band. A creatinine clearance calculation answers another question and cannot substitute for the serum creatinine observation required here.

Cardiovascular points likewise require the qualifying support category, not only the resulting pressure. MAP 75 without an infusion scores 0, but MAP 75 while receiving qualifying norepinephrine 0.08 µg/kg/min scores 3. Restored pressure does not erase the support requirement. The mean arterial pressure calculator explains MAP estimation; the SOFA criterion and a resuscitation target are different uses of that measurement.

An empty box is not a normal organ

If five subscores total 7 and the sixth is unavailable, 7 is a known-system subtotal, not a complete SOFA score. This implementation leaves the total and baseline change unavailable until every organ has the required observations. It deliberately requires both renal inputs, even when one known observation would already yield 4 points, to make the assessment-completeness rule consistent.

Sedation and intubation complicate GCS interpretation, while renal replacement therapy alters the values used for renal scoring. A published methods review discusses these problems and the need for explicit measurement rules [3]. An unassessable neurological examination should not silently become either GCS 15 or GCS 3. Record a protocol-supported value or preserve the uncertainty.

Similarly, platelets 90 ×10⁹/L and 90 ×10³/µL describe the same count, but 90,000 entered into a field expecting ×10⁹/L describes something entirely different. Check the printed unit before transcribing. The platelet count calculator gives count-specific context; its bleeding-risk interpretation is separate from the SOFA coagulation subscore.

SOFA-1, SOFA-2 and qSOFA: record the version

SOFA-2 was published in 2025 as an updated assessment of organ dysfunction in adult critical care [4]. This page retains the original SOFA criteria associated with Sepsis-3 and labels them SOFA-1. A change from 5 to 7 is interpretable as a two-point difference only when the measurements use a comparable version and assessment method.

qSOFA is another instrument: three bedside findings, each worth one point. It does not reconstruct the six-system laboratory-based score. The 2026 Surviving Sepsis Campaign recommends NEWS, NEWS2, MEWS or SIRS over qSOFA alone for hospital sepsis screening [5]. Neither a reassuring bedside score nor an incomplete laboratory score should delay evaluation of suspected sepsis.

Mortality is not a seventh component to add to SOFA. A personal percentage would require a separately specified and validated prediction model, a population and an outcome timeframe. For a useful record, retain the version, window, six subscores and the baseline used for comparison. That preserves more actionable information than assigning an unsupported survival percentage to a total of 9.

Sources and implementation notes

1. Singer et al. Sepsis-3 consensus definitions. JAMA, 2016; Table 1 and organ-dysfunction criteria.
2. Vincent et al. The SOFA score to describe organ dysfunction/failure. Intensive Care Medicine, 1996.
3. Lambden et al. SOFA development, utility and challenges of assessment. Critical Care, 2019.
4. SOFA study group: SOFA-2 development and validation publications, 2025.
5. Surviving Sepsis Campaign adult guidelines, 2026: screening recommendations.

Implementation convention: scoring uses unrounded values and continuous bands, including bilirubin ≥12 mg/dL, creatinine ≥5 mg/dL and dopamine ≤5 µg/kg/min. This closes gaps and endpoint ambiguities in rounded reproductions of the original table. No SpO₂ substitution, drug-equivalence conversion or automatic missing-data imputation is performed. Numerical test coverage is not independent clinical validation.