CURB-65 Pneumonia Severity Calculator
Calculate the CURB-65 score for community-acquired pneumonia severity and disposition guidance.
About this calculator
CURB-65 is a five-item pneumonia severity score, derived by Lim and colleagues in a 2003 international study of over 1,000 patients hospitalized with community-acquired pneumonia (published in Thorax). Each of the five criteria -- new Confusion, blood urea above 7 mmol/L, Respiratory Rate at or above 30 breaths/min, low blood pressure (systolic under 90 mmHg or diastolic 60 mmHg or below), and Age 65 or older -- contributes exactly one point if present, so Confusion (the first criterion entered) moves the Total Score by exactly as much as toggling any other single criterion: one point each, with no criterion weighted more heavily than another. The original derivation study reported 30-day mortality rising from 0.7% at a score of 0 up through 3.2%, roughly 13%, 17%, and 41.5% at scores 1 through 4, to 57% at the maximum score of 5 -- the same mortality figures this calculator returns for each score.
Broadly, a score of 0-1 supports outpatient treatment, a score of 2 suggests a short inpatient stay or closely supervised outpatient care, and a score of 3 or higher points toward hospital admission, with scores of 4-5 prompting consideration of ICU care. CURB-65 is a decision-support tool, not a replacement for clinical judgment about comorbidities, social circumstances, or a patient's ability to take oral therapy reliably at home.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
CURB-65 Score
0/ 5
30-Day Mortality
0.7%
Figures current as of 2003. Source: Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital. Thorax. 2003;58:377-382 — adopted in British Thoracic Society pneumonia guidelines.
How to Use This Calculator
- Enter 0 or 1 for each CURB-65 criterion: confusion, BUN > 7 mmol/L, respiratory rate ≥ 30, low BP, and age ≥ 65.
- Review CURB-65 Score and recommended disposition (outpatient, admission, or ICU).
- Score 0–1: outpatient; 2: short inpatient stay or close follow-up; 3+: hospital admission.
What each input means
- Confusion
- New mental confusion (AMT <=8 or disorientation) (+1 point).
- Blood Urea > 7 mmol/L
- BUN > 19 mg/dL or urea > 7 mmol/L (+1 point).
- Respiratory Rate >= 30
- Respiratory rate of 30 breaths/min or more (+1 point).
- Low Blood Pressure
- Systolic BP <90 mmHg or diastolic BP <=60 mmHg (+1 point).
- Age >= 65
- Patient is 65 years or older (+1 point).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersConfusion = 0, Blood Urea > 7 mmol/L = 0, Respiratory Rate >= 30 = 0, Low Blood Pressure = 0 = 5 input(s) provided
- Calculate CURB-65 ScoreCURB-65 Score0 = 0
- Calculate 30-Day Mortality30-Day Mortality0.7 = 0.7%
- Calculate DispositionDisposition1 = 1
Figures and sources
- CURB-65 score (community-acquired pneumonia severity) (2003) — Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital. Thorax. 2003;58:377-382 — adopted in British Thoracic Society pneumonia guidelines.
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What are the five criteria in the CURB-65 score?
Confusion (new mental confusion or disorientation), blood Urea over 7 mmol/L (roughly 19 mg/dL BUN), Respiratory rate of 30 breaths per minute or higher, low Blood pressure (systolic under 90 mmHg or diastolic 60 mmHg or below), and Age 65 or older -- each criterion present adds exactly one point to the Total Score, out of a maximum of 5.
Where do the CURB-65 mortality percentages come from?
They come from Lim et al.'s 2003 derivation and validation study in Thorax, which followed over 1,000 hospitalized community-acquired pneumonia patients and reported 30-day mortality by score: 0.7% at score 0, rising through the low-to-mid teens at scores 1-3, up to 41.5% at score 4 and 57% at the maximum score of 5.
Does the order I enter the CURB-65 criteria change the score?
No. Each of the five criteria -- Confusion, Urea, Respiratory Rate, Blood Pressure, and Age -- adds exactly one point when present, with no criterion weighted more than another, so the Total Score only depends on how many criteria are present, never on which ones or the order they're entered.
What does a CURB-65 score of 2 mean for treatment?
A score of 2 generally suggests a short inpatient stay or hospital-supervised outpatient treatment rather than routine outpatient antibiotics alone. It sits between scores of 0-1, which typically support outpatient care, and scores of 3 or higher, which point more strongly toward hospital admission.
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