# Sepsis Calculator (SIRS Criteria and Sepsis Screening)

URL: https://speedycalculator.com/calculators/health/sepsis/
Last updated: 2026-10-30

> The sepsis calculator checks the SIRS criteria – temperature, heart rate, respiratory rate or PaCO₂ and white cell count – together with suspected infection, and shows whether a patient meets the classic sepsis definition and needs urgent assessment.

## Inputs

- Temperature above 38 °C or below 36 °C
- Heart rate above 90 bpm
- Respiratory rate above 20/min or PaCO₂ below 32 mmHg
- WBC above 12,000 or below 4,000/µL, or more than 10% bands
- Suspected or confirmed infection
- New organ dysfunction or hypotension

## Results

- SIRS criteria met
- Screen

## Formula

```
Score = sum of the points for each item
```

## Explanation

Systemic inflammatory response syndrome (SIRS) criteria were used to define sepsis from 1991 to 2016. Sepsis-3 now defines sepsis as life-threatening organ dysfunction due to infection (SOFA increase ≥ 2), but SIRS remains a sensitive screening tool used in many hospitals.

### How to use the Sepsis Calculator

- **Temperature above 38 °C or below 36 °C**
- **Heart rate above 90 bpm**
- **Respiratory rate above 20/min or PaCO₂ below 32 mmHg**
- **WBC above 12,000 or below 4,000/µL, or more than 10% bands**
- **Suspected or confirmed infection**
- **New organ dysfunction or hypotension**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Each answer carries the points shown in the published score. The calculator adds them up and maps the total to the published interpretation.

### Scoring table

ItemAnswers and pointsTemperature above 38 °C or below 36 °CNo = 0; Yes = 1Heart rate above 90 bpmNo = 0; Yes = 1Respiratory rate above 20/min or PaCO₂ below 32 mmHgNo = 0; Yes = 1WBC above 12,000 or below 4,000/µL, or more than 10% bandsNo = 0; Yes = 1Suspected or confirmed infectionNo = 0; Yes = 1New organ dysfunction or hypotensionNo = 0; Yes = 1

### Inputs explained

FieldWhat to enterTemperature above 38 °C or below 36 °CChoose one: No, YesHeart rate above 90 bpmChoose one: No, YesRespiratory rate above 20/min or PaCO₂ below 32 mmHgChoose one: No, YesWBC above 12,000 or below 4,000/µL, or more than 10% bandsChoose one: No, YesSuspected or confirmed infectionChoose one: No, YesNew organ dysfunction or hypotensionChoose one: No, Yes
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Temperature above 38 °C or below 36 °C: Yes; Heart rate above 90 bpm: Yes; Respiratory rate above 20/min or PaCO₂ below 32 mmHg: No; WBC above 12,000 or below 4,000/µL, or more than 10% bands: No; Suspected or confirmed infection: Yes; New organ dysfunction or hypotension: No.

Results — **SIRS criteria met = 2 of 4**; Screen = Possible sepsis – assess for organ dysfunction (SOFA).

## Key terms

- **SIRS**: Systemic inflammatory response syndrome.

## FAQ

**What are the SIRS criteria?**
Temperature, heart rate, breathing rate/PaCO₂ and white cell count; 2 or more is SIRS.

**What is the current sepsis definition?**
Sepsis-3: life-threatening organ dysfunction (SOFA rise ≥ 2) caused by infection.

**What should happen if sepsis is suspected?**
Rapid antibiotics, cultures, lactate and fluids according to the hour-1 bundle.


## Sources

- [Bone RC et al. Definitions for sepsis and organ failure (ACCP/SCCM). Chest, 1992](https://pubmed.ncbi.nlm.nih.gov/1303622/)
- [Evans L et al. Surviving Sepsis Campaign 2021 guidelines. Crit Care Med, 2021](https://pubmed.ncbi.nlm.nih.gov/34605781/)