Sepsis-3 Calculator (sepsis and septic shock criteria from SOFA change)

Understanding the Sepsis-3 calculator — concept and principle

This calculator checks the Sepsis-3 (2016) criteria: whether a suspected infection is accompanied by a rise of 2 or more points in the SOFA organ-failure score, which defines sepsis, and whether vasopressor need and raised lactate also meet the definition of septic shock.

SOFA rise with infection: with the default inputs the result is Sepsis met (septic shock not met).

How it is calculated

Sepsis = suspected or confirmed infection AND current SOFA − baseline SOFA ≥ 2

Septic shock = sepsis AND vasopressors needed to keep mean arterial pressure ≥ 65 mmHg AND lactate > 2 mmol/L, despite adequate fluids

Baseline SOFA is assumed to be 0 unless the person already had known organ dysfunction.

The principle

The Third International Consensus defined sepsis as life-threatening organ dysfunction caused by a dysregulated response to infection. Organ dysfunction is measured by the SOFA score, and a rise of 2 points was associated with a hospital mortality of about 10% in the data used. Septic shock is the subset with circulatory and cellular failure; its mortality exceeds 40%. The older SIRS criteria, based on fever and white cell count, were dropped because they also flagged many people with uncomplicated infection.

Worked example

Default inputs: infection yes, baseline SOFA 0, current SOFA 4, no vasopressors, lactate 2.6 mmol/L.

Change in SOFA = 4 − 0 = 4.
Infection and rise ≥ 2 → sepsis Met.
No vasopressors → septic shock Not met (lactate alone does not meet it).
Reason: Sepsis: infection with SOFA rise of 2 or more.

Each point is the calculator re-run with only “Current SOFA score” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Current SOFA score	Change in SOFA (points)
1	1
2	2
3	3
4	4
5	5
6	6
8	8

How to read the result

Where does your result fall?

Meeting the sepsis criteria means a high-risk infection that needs urgent treatment: antibiotics, fluids and source control according to sepsis guidelines. Septic shock needs intensive care. Not meeting the criteria does not mean the infection is harmless; patients can deteriorate quickly.

Common mistakes

Using a high SOFA that was already present before the infection as a "rise".
Diagnosing septic shock without adequate fluid resuscitation first.
Waiting for criteria to be met before treating a seriously ill patient.

Keep in mind: Sepsis is a medical emergency. This page checks published criteria only and is not a diagnosis or treatment guide.

Frequently asked questions

What is qSOFA?

A quick bedside screen (breathing rate 22 or more, altered mentation, systolic BP 100 or less) to flag patients at risk outside the ICU; it is not a definition of sepsis.

Why was SIRS removed from the definition?

SIRS was too non-specific, flagging many patients with simple infections.

What lactate level counts?

Above 2 mmol/L (18 mg/dL) for septic shock.

Sources: Singer M, Deutschman CS, Seymour CW, et al., "The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)", JAMA 2016;315(8):801–810

Checked 9 Nov 2026. Singer M, Deutschman CS, Seymour CW et al., “The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)”, JAMA 2016;315(8):801–810; criteria as summarised in Whittle J, Walker D, “The new international sepsis guidelines (Sepsis-3): the central message remains”, Br J Hosp Med 2016;77(4):208–211, Table 4.

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