CURB-65 Score Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The CURB-65 score adds 1 point for each of these 5 criteria present: Confusion, elevated Urea, elevated Respiratory rate, low Blood pressure, age ≥65. A score of 0 or 1 corresponds to low risk, while a score of 3 to 5 signals high risk generally requiring hospitalization.
Explanation
The CURB-65 score, developed by Lim and colleagues in 2003, is a simple, widely used clinical tool for assessing the severity of community-acquired pneumonia (contracted outside a hospital setting) and guiding the decision between outpatient care and hospitalization. Its name is an acronym for the five criteria it assesses, each worth 1 point if present: new-onset Confusion, blood Urea above 7 mmol/L (19 mg/dL, a marker of dehydration or associated kidney involvement), Respiratory rate of 30 breaths per minute or more, low Blood pressure (systolic below 90 mmHg or diastolic 60 mmHg or below), and age 65 or older. The total score, ranging from 0 to 5, translates directly into a risk level and a care recommendation: a score of 0 or 1 corresponds to low mortality risk, compatible with outpatient care in most cases; a score of 2 signals moderate risk, for which short-stay hospitalization or close monitoring is generally considered; a score of 3 to 5 corresponds to high risk, pointing toward hospitalization and, for the highest scores, toward evaluating intensive care admission. This score remains a decision-support tool for healthcare professionals, to be interpreted alongside the patient's overall clinical picture (comorbidities, social context, symptom progression) and never as a substitute for a full medical examination — a fast or irregular resting heart rate is another vital sign often checked alongside these five criteria, much like the shock index combines heart rate and blood pressure into a single severity marker.
Example: confusion and age 70
Inputs
Confusion: yes. Elevated urea: no. Elevated respiratory rate: no. Low blood pressure: no. Age ≥65: yes.
Calculation
Total score = 1 (confusion) + 0 + 0 + 0 + 1 (age) = 2.
Result
This score of 2 corresponds to moderate risk, for which short-stay hospitalization is generally considered.
Frequently asked questions
Does the CURB-65 score replace medical advice for pneumonia?
No, this score is a decision-support tool for healthcare professionals to objectify pneumonia severity and guide care, but it never replaces a full clinical examination or a doctor's judgment, which accounts for other factors (comorbidities, oxygen saturation, social context) not covered by this score.
Why does blood urea factor into this respiratory severity score?
Elevated urea often reflects dehydration associated with severe infection (loss of appetite, fever) or kidney involvement that sometimes accompanies severe forms of pneumonia, both associated with a less favorable outlook. It's a simple, quickly available lab marker, which makes it a good complement to the score's purely clinical criteria.
Is there a simplified version without the urea test?
Yes, a variant called CRB-65 (without the U for urea) exists and is used particularly when a blood test isn't immediately available, for example in primary care or a first point of contact. It's slightly less precise than the full CURB-65 but remains useful when a quick lab result isn't available.