qSOFA Calculator
The formula
What the qsofa tells you
Three bedside variables — fast breathing, altered mentation, low systolic pressure — that approximate SOFA anywhere a blood gas is not.
Calculation: qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk. Enter your inputs and every substitution is shown below the result.
Reading the result
High specificity makes a positive useful for escalation; mediocre sensitivity makes a negative worthless for exclusion.
Rules of thumb: Used in ED triage, wards and pre-hospital; ≥2 = trigger pathway
Limitations and best practice
Later trials showed qSOFA is no better than simple clinical gestalt or SIRS for screening — the 2021 SSC guidance downgraded it deliberately.
This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Frequently asked questions
Does qSOFA replace SIRS?
What counts as altered mentation?
Source & methodology
Seymour JAMA 2016; SSC 2021 guidance.
qSOFA: what this tool answers
You are here because you need a specific number, and you want to see how it was produced before you rely on it. qSOFA is the kind of number people argue about from memory. This page ends that argument with arithmetic you can watch happen: enter your figures, get qSOFA in real time, and see every substitution printed below.
People rarely disagree about arithmetic; they disagree about assumptions that were never written down. Printing the substitution and the sensitivity ranking removes that category of disagreement for qSOFA.
It helps to separate the mechanics from the interpretation. The mechanics are fixed: qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk. Anyone, anywhere, entering the same inputs will get the same 1. The interpretation is where experience counts: whether 1 is good, normal or alarming depends on comparisons covered below, and that is the part most articles about qSOFA never explain.
Nothing below is stock text pasted around a number: the worked example computes qSOFA = 1 from this tool’s own defaults. Work down the page and by the end you could re-derive the result in a spreadsheet from memory.
The qSOFA formula, explained
Here is the complete model this tool runs — qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk — with each input explained below. If a competitor’s page gives you a different answer from the same inputs, this is the text that settles which of you is right.
Respiratory rate ≥22? (0/1) (example value 1) is a quantity rather than a category — precision here is cheap and worth having. Rates are the most mis-transcribed input on any page like this; copy it from the document rather than retyping from memory.
Altered mentation? (0/1) (example value 0) is a quantity rather than a category — precision here is cheap and worth having. The example value is there to demonstrate the mechanics, not to describe your situation — overwrite it.
Systolic BP ≤100? (0/1) (example value 0) is a quantity rather than a category — precision here is cheap and worth having. If you are unsure what belongs in this field, look at the printed steps: the substitution shows exactly how the engine uses it.
The default qSOFA calculation, written out in full
Rather than describe the calculation, here it is end to end — every substitution in order, starting from the inputs above. Starting figures: Respiratory rate ≥22? (0/1), Altered mentation? (0/1), Systolic BP ≤100? (0/1). The endpoint of that chain is 1 of qSOFA, sitting in the “A qSOFA of 1 does not flag, but absence of criteria never rules sepsis out” band.
- RR≥22: yes · Mentation: normal · SBP≤100: no
- Count = 1; threshold ≥2 for concern
- qSOFA is a bedside screen for wards and EMS — not a diagnostic criterion
Criteria met — 1 of 3. This is the number experienced users quote when the headline alone would mislead.
Full-SOFA equivalence — screen negative. This is the number experienced users quote when the headline alone would mislead.
Sensitivity of qSOFA — low (~50–60%). Read next to the headline, this is the figure that shows the shape of the trade-off.
Specificity of qSOFA — high (~80–90%). Read next to the headline, this is the figure that shows the shape of the trade-off.
Keep this worked example open while you enter your own figures: matching the shape of the substitution is the fastest way to spot a unit or convention mistake.
Interpreting the qSOFA verdict
Nobody acts on a bare figure — they act on a figure with a comparison attached. On the example inputs the band reads “A qSOFA of 1 does not flag, but absence of criteria never rules sepsis out”; your own figures place you on a different rung of the same ladder. The practical reading rules: read the band as a starting hypothesis, then test it: change the two dominant inputs by ten percent and see whether the verdict survives. Verdicts that survive stress are the ones worth acting on.
The comparison worth making is not with somebody else’s qSOFA but with the version of your own situation measured last quarter — same formula, same conventions, different inputs.
Common mistakes with qSOFA (and the fix)
Later trials showed qSOFA is no better than simple clinical gestalt or SIRS for screening — the 2021 SSC guidance downgraded it deliberately. This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Comparing a qSOFA computed here with a figure from another source that uses different conventions. Same name, different denominator — the disagreement is usually in the definitions, not the data.
Another is comparing across contexts: a qSOFA computed with one set of conventions should never be lined up against a figure computed with another. Check the inputs behind both before ranking them.
qSOFA verification checklist
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- State, in one sentence, which convention each rate, unit or period in the form is using.
- Confirm the inputs are dated — a qSOFA figure should carry the date it was computed.
- Recompute once with the dominant input deliberately set low, and see whether the decision changes.
- Confirm the example values are plausible for your own situation before replacing them.
- Run the ±10 % stress on the top two levers and check that your conclusion survives both.
How to use the qSOFA tool properly
Using a calculator well sounds trivial, but the difference between a decision-grade figure and a throwaway one lives entirely in the routine. The routine for qSOFA takes a minute to learn and applies to every input above.
Step 1 — start from evidence. The inputs behind qSOFA are respiratory rate ≥22? (0/1), altered mentation? (0/1), systolic bp ≤100? (0/1). Write them down with their source next to each one; if you cannot name where a figure came from, that is the input most likely to be wrong. Comparisons are cheap: run the identical calculation for the alternative and look at the gap.
Step 2 — compute the version you would not be embarrassed by. If a stranger audited your inputs, which set would you hand over? Enter that set, read the result, and treat everything else as upside. Suspiciously tidy answers deserve the same scrutiny as untidy ones.
Step 3 — isolate your variables. Change one field, observe, revert. The live sensitivity list does the ranking for the default inputs; verify it against your own, because dominance shifts when the starting point shifts. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
Step 4 — stress before you commit. A decision that survives a ten-percent squeeze on its two biggest inputs needs no luck to be sound. One that does not survive is a decision about hope, not about arithmetic. Numbers are cheap to produce and expensive to retract; the extra minute is the cheapest insurance available.
Step 5 — schedule the next run. In Health & Medical the inputs drift quietly. Put a reminder a quarter out, re-enter the same fields, and read the change rather than the level. A figure nobody can reproduce is a figure nobody will act on twice.
Where qSOFA matters in practice
Most Clinical Calculators disagreements are arithmetic disagreements in disguise. When qSOFA of 1 sits on the table with its working shown, the conversation stops being about who sounds more confident and starts being about which input is wrong. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
The companion outputs — Criteria met and Full-SOFA equivalence — exist for the second stage of that screen: the headline sizes the prize, while the companions describe the trade-off you are accepting to get it. Re-running a number costs seconds; retracting a decision costs considerably more.
Re-running this page costs nothing and catches the slow drifts that never announce themselves. In Health & Medical the expensive mistakes are rarely sudden; they are small changes in Respiratory rate ≥22? (0/1) that nobody recalculated for a year. If the answer changes your behaviour, it deserves a second run with different assumptions.
Quick answers: what searchers ask about qSOFA
What is a typical qSOFA?
With the example inputs on this page the result is 1, labelled “A qSOFA of 1 does not flag, but absence of criteria never rules sepsis out”. “Typical” varies with situation, which is why every result here ships with its verdict band and its sensitivity list: they turn one figure into a range you can locate yourself inside.
How do I calculate qSOFA by hand?
Three steps: write the formula (qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk), insert your values, and simplify. The worked example section shows exactly that chain for the default inputs; replicating it once on paper teaches you more about qSOFA than any number of calculator runs.
Is the qSOFA result of 1 good or bad?
Neither, on its own — the label “A qSOFA of 1 does not flag, but absence of criteria never rules sepsis out” is the band this figure falls in for the example inputs, and your own inputs will place you elsewhere on the same ladder. Judge the number against your history and your alternatives.
How accurate is qSOFA for me personally?
The formula encodes averages; body-composition and measurement error typically shifts results by a few percent in either direction. Use ranges and trends, and treat any single 1 as approximate.
How often should I check qSOFA?
Whenever an input changes by more than a few percent, and otherwise on the rhythm of your decisions — before a purchase, a review, a renewal. qSOFA is a snapshot, not a subscription; stale snapshots are the most common silent error in Health & Medical planning.
Does qSOFA replace SIRS?
It was proposed to, but the 2021 Surviving Sepsis Campaign recommends against using it alone for screening.
What counts as altered mentation?
Any acute GCS drop below baseline — the same definition used elsewhere.
Do I need an account to use this qSOFA calculator?
No, and no data leaves the tab. The engine runs in the page itself, which is why the worked example, the bands and the sensitivity ranking all respond instantly to your keystrokes.
The vocabulary of qSOFA
- Criteria met
- 1 of 3 on the example inputs — a companion figure printed beside the headline of qSOFA so that no result is read in isolation.
- Full-SOFA equivalence
- screen negative in the default qSOFA calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Sensitivity of qSOFA
- low (~50–60%) for the qSOFA worked case; it sits next to the main result because it carries context the headline leaves out.
- qSOFA
- The primary output of this tool: 1 for the default inputs, computed exactly from qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk.
- Worked example
- The step-by-step substitution printed above, so the arithmetic can be re-derived by hand or in a spreadsheet.
- Verdict band
- The interpretation attached to a result (“A qSOFA of 1 does not flag, but absence of criteria never rules sepsis out” on these inputs), which turns a bare number into a position on a scale.
Method, sources and what this tool cannot tell you
Everything above runs on one stated formula, applied without hidden coefficients: qSOFA = count of the three bedside criteria (0–3); ≥2 flags poor outcome risk. Source of record: Seymour JAMA 2016; SSC 2021 guidance. Specialist software layers extra coefficients on top of the same algebra; none are hidden here, and that transparency is what makes a disagreement traceable to a specific input instead of a black box.
Nothing here replaces a qualified professional, and nothing here is approximate either — the arithmetic is exact, and the honesty is in the inputs you supply. Every intermediate value is printed so that the result can be checked line by line rather than accepted or rejected wholesale.
Next steps after the calculation
Save the number together with its inputs and today’s date; a qSOFA figure without context is unusable the moment an input changes.
This page was written for people who need one trustworthy number before their next decision, and the promise is that nothing above required trust. Bookmark the tool, re-run it whenever an input moves by more than a few percent, and keep the date with the number.