Editverse · Clinical Decision Tools
Free CURB-65 Calculator (2026)
CURB-65 is a five-criterion clinical prediction rule that estimates 30-day mortality risk in adults with community-acquired pneumonia, and is one of the most widely used tools for deciding whether a patient can be safely treated as an outpatient, needs a short inpatient stay, or requires more intensive hospital care. It scores one point each for new-onset Confusion, elevated blood Urea, elevated Respiratory rate, low Blood pressure, and Age 65 or older — hence the name CURB-65. Each criterion is either present or absent, so the total score runs from 0 to 5, and higher scores track a substantially higher approximate 30-day mortality: roughly 1.5% at a score of 0–1, 9.2% at 2, and 22% at 3 or above. The calculator below produces that total, an approximate mortality band, and a plain-language site-of-care suggestion clinicians can use alongside — not instead of — their own bedside judgment. It is built for emergency physicians, hospitalists, primary care clinicians, and trainees who need a fast, citable severity estimate at the point of a pneumonia diagnosis. Enter the five criteria below to calculate a patient’s CURB-65 score instantly.
Clinical decision-support aid, not a substitute for clinical judgment. These tools implement published scoring criteria for education and workflow support. They are not a medical device and have not been reviewed by the FDA or any regulatory body. Every result should be interpreted by a qualified clinician in the context of the full clinical picture, not used as a standalone diagnostic or treatment decision.
Pneumonia severity
CURB-65
Estimates 30-day mortality risk in community-acquired pneumonia from five bedside-available criteria, to help guide the site-of-care decision.
Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377–382.
A fully worked example
Consider a 72-year-old brought in with new confusion and a respiratory rate of 32 breaths per minute. Blood pressure and urea are both within normal limits, so those two criteria are not met. Scoring CURB-65: confusion present (+1), urea normal (0), respiratory rate ≥30/min present (+1), blood pressure normal (0), and age ≥65 present (+1) — a total of 3 out of 5. A score of 3 falls in the high-risk band, with an approximate 30-day mortality around 22%, which typically warrants hospital admission and, if the score reaches 4 or 5, consideration of ICU-level assessment. These same three criteria are already loaded as the calculator’s defaults above — try toggling them to see the readout change.
Methods, assumptions, and when not to use CURB-65
For a manuscript methods section, CURB-65 can be cited in a single sentence: “Pneumonia severity was assessed using the CURB-65 score, a five-item rule (Confusion, Urea, Respiratory rate, Blood pressure, Age ≥65) validated to stratify 30-day mortality risk in community-acquired pneumonia (Lim et al., Thorax 2003).” Because CURB-65 is a fixed, published point-score rather than a fitted or site-specific model, citing its derivation and validation study is sufficient methodological documentation.
CURB-65 was derived and validated specifically for community-acquired pneumonia, and it estimates mortality risk to help triage site-of-care — it is not a diagnostic test for pneumonia itself, and it should not override clinical judgment about factors it does not capture: hypoxemia and oxygen requirement, decompensated comorbidities such as unstable heart failure or poorly controlled diabetes, or social circumstances like a patient’s ability to reliably take oral antibiotics, attend follow-up, or manage safely at home. A low CURB-65 score in a hypoxic or socially vulnerable patient does not, by itself, make outpatient treatment appropriate; the score is one input alongside a full clinical assessment, not a replacement for one.
What do the five CURB-65 criteria mean?
CURB-65 stands for Confusion (new disorientation to person, place, or time, often approximated with an Abbreviated Mental Test Score of 8 or below), Urea greater than 7 mmol/L (roughly equivalent to a BUN above 19 mg/dL), Respiratory rate of 30 breaths per minute or higher, Blood pressure that is low (systolic under 90 mmHg or diastolic 60 mmHg or below), and Age 65 or older. Each present criterion adds one point, for a total score from 0 to 5.
How is the CURB-65 score used to decide admission?
In general, a score of 0 or 1 is associated with roughly 1.5% 30-day mortality and is often manageable with outpatient treatment; a score of 2 carries an intermediate mortality risk around 9.2% and typically prompts a short inpatient stay or closely supervised outpatient care; and a score of 3 or higher is associated with roughly 22% mortality and usually warrants hospital admission, with scores of 4 or 5 prompting consideration of ICU-level assessment. These bands are a starting point for the admission decision, not a rule that overrides clinical judgment.
Is CURB-65 the same as CRB-65?
No. CRB-65 is a simplified variant that drops the urea criterion so it can be used without a blood test, which makes it useful in primary care or resource-limited settings where labs are not immediately available. CURB-65, the version implemented here, includes urea and was the version validated in the original 2003 derivation study.
Primary references
Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377–382.
Running a pneumonia or respiratory-admission cohort study?
Severity scores like CURB-65 are only as useful as the outcomes data validating them. If your next project involves a pneumonia or respiratory-admission registry cohort, Editverse’s NTDB/TQP Trauma Registry Study service handles registry access, cohort definition, risk-adjusted modelling, and a publication-ready manuscript. See the registry study service