SIRS Criteria for Sepsis Calculator
Check four binary SIRS criteria to determine if a patient meets the threshold for systemic inflammatory response syndrome.
Use the SIRS Criteria for Sepsis Calculator
SIRS Criteria Input
Check each criterion that applies. Two or more criteria met = SIRS present.
Criterion 1 — Temperature
Abnormal body temperature
Met if >38°C (100.4°F) or <36°C (96.8°F)
Criterion 2 — Heart Rate
Tachycardia
Met if >90 bpm
Criterion 3 — Respiratory Rate / PaCO2
Tachypnea or hypocapnia
Met if RR >20/min OR PaCO2 <32 mmHg
Criterion 4 — WBC Count
Abnormal white blood cell count
Met if WBC >12,000/mm³ or <4,000/mm³ or bands >10%
Enter values and press Calculate to see the SIRS score and interpretation.
SIRS Score
—
out of 4 criteria
Criteria Breakdown
| Criterion | Value | Met |
|---|
Sepsis Context
For educational purposes only. Clinical decisions require assessment by qualified healthcare providers. SIRS criteria predate Sepsis-3 (2016); current guidelines use SOFA/qSOFA for sepsis identification.
| Criterion | Threshold (met if...) |
|---|---|
| Temperature | >38°C (100.4°F) or <36°C (96.8°F) |
| Heart Rate | >90 bpm |
| Respiratory Rate / PaCO2 | >20 breaths/min OR PaCO2 <32 mmHg |
| WBC Count | >12,000/mm³ or <4,000/mm³ or >10% band forms |
Interpretation: 0–1 criteria = SIRS not met. 2–4 criteria = SIRS present. SIRS + suspected/confirmed infection = historical sepsis definition (Bone et al., 1992; ACCP/SCCM Consensus).
Summary
SIRS (Systemic Inflammatory Response Syndrome) criteria define a non-specific systemic response to infection, trauma, or other insults. A patient meets SIRS when two or more of four criteria are present: abnormal temperature, tachycardia, tachypnea or low PaCO2, and abnormal WBC count. When SIRS occurs alongside suspected or confirmed infection, it historically qualified as sepsis under pre-Sepsis-3 definitions. Sepsis-3 (2016) replaced SIRS with SOFA/qSOFA for sepsis identification, but SIRS criteria remain widely taught and used in initial triage.
How it works
- Review the patient's current vital signs and lab values.
- Check each of the four SIRS criteria: temperature, heart rate, respiratory rate (or PaCO2), and WBC count.
- Each criterion that is met adds 1 point to the SIRS score.
- A total of 2 or more points indicates SIRS is present.
- If SIRS is met alongside suspected or confirmed infection, consider sepsis workup.
- Note: Sepsis-3 guidelines use SOFA/qSOFA; consult your institution's protocol.
Use cases
- Initial triage screening for patients with suspected infection.
- Teaching clinical decision-making for medical and nursing students.
- Reviewing historical sepsis cases that predate Sepsis-3 criteria.
- Quick bedside checklist in emergency or ICU settings.
- Continuing medical education on sepsis definitions and evolution.
- Protocol review comparing SIRS-based versus SOFA-based sepsis identification.