SIRS Calculator

Patient group

Important: SIRS is a measure of systemic inflammation and is not synonymous with sepsis. Infection must be assessed separately.

Patient information

Age

years

Temperature measurement

Clinical measurements

Temperature

°C

Heart rate

beats/minute

Respiratory rate

breaths/minute

PaCO₂

mmHg — adult criterion only

White blood cell count

×10³/µL (×10⁹/L)

Immature / band neutrophils

% of WBC

Result

SIRS criteria met

0 / 4

Enter patient measurements

The calculator will assess each criterion automatically.

Reference thresholds

Criterion	SIRS threshold	Interpretation
Temperature	>38°C or <36°C	Abnormal temperature
Heart rate	>90 beats/min	Tachycardia
Respiratory rate	>20 breaths/min	Tachypnoea
PaCO₂	<32 mmHg	Alternative respiratory criterion
WBC	>12,000 or <4,000 /µL	Leukocytosis or leukopenia
Immature/band forms	>10%	Counts as WBC criterion

Age	Heart rate	Respiratory rate	WBC
0 days–1 week	>180 or <100	>50	>34
1 week–1 month	>180 or <100	>40	>19.5 or <5
1 month–1 year	>180 or <90	>34	>17.5 or <5
1–5 years	>140	>22	>15.5 or <6
6–12 years	>130	>18	>13.5 or <4.5
13–17 years	>110	>14	>11 or <4.5

Pediatric temperature criterion: >38.5°C or <36°C. More than 10% immature neutrophils also satisfies the leukocyte criterion.

Clinical interpretation

SIRS ≥2: The patient meets the SIRS definition when the required criteria are present. This does not by itself establish sepsis.

Consider the clinical context: infection, trauma, burns, pancreatitis, surgery, ischemia, malignancy, medications, transfusion reactions and other inflammatory conditions can produce SIRS.

Do not use SIRS alone to rule out sepsis. A patient can have serious infection or organ dysfunction without meeting SIRS thresholds.

References

Bone RC, Balk RA, Cerra FB, et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Chest. 1992;101(6):1644–1655.
PubMed
Goldstein B, Giroir B, Randolph A. International pediatric sepsis consensus conference: definitions for sepsis and organ dysfunction in pediatrics. Pediatric Critical Care Medicine. 2005;6(1):2–8.
PubMed
Schlapbach LJ, Watson RS, Sorce LR, et al. International Consensus Criteria for Pediatric Sepsis and Septic Shock. JAMA. 2024;331(8):665–674.
PubMed
Pediatric SIRS age-specific criteria are reproduced from the International Pediatric Sepsis Consensus definitions.
Pediatric SIRS criteria – PMC

Calculator purpose: educational and clinical decision-support aid. It does not replace clinical assessment, local protocols, or specialist advice. Thresholds should be checked against the guideline adopted by your institution.