CURB-65 Calculator — Pneumonia Severity Score
Estimate the 30-day mortality risk of community-acquired pneumonia (CAP) using the CURB-65 clinical score. Score one point for each criterion present — Confusion, elevated Urea, high Respiratory rate, low Blood pressure, and Age ≥ 65 — to guide inpatient vs outpatient management.
Confusion (new disorientation / altered mental status)
Urea > 7 mmol/L (or BUN > 19 mg/dL)
Respiratory rate ≥ 30 breaths/min
Blood pressure: systolic < 90 mmHg or diastolic ≤ 60 mmHg
Age ≥ 65 years
Range 0 (lowest risk) to 5 (highest risk)
- 1
Clinical criteria: Confusion + Urea + Resp rate + Blood pressure
0 + 0 + 0 + 0 = 0One point awarded for each criterion that is present. - 2
Add Age ≥ 65 criterion → CURB-65 total
0 + 0 = 0
How does this calculator work?
CURB-65 = C + U + R + B + Age-65, each 0 or 1. Score 0–1: low risk (~1–3 % 30-day mortality), home treatment usually appropriate. Score 2: moderate risk (~9–13 %), consider hospitalisation. Score 3–5: high risk (15–57 %), hospital admission recommended; consider ICU at 4–5.
Formula
How this is calculated
The CURB-65 score was derived and validated by the British Thoracic Society (BTS) as a simple bedside tool to predict 30-day all-cause mortality in adults presenting with community-acquired pneumonia. One point is awarded for each of five criteria: new-onset Confusion or disorientation; blood Urea nitrogen > 7 mmol/L (or BUN > 19 mg/dL); Respiratory rate ≥ 30 breaths per minute; systolic Blood pressure < 90 mmHg or diastolic ≤ 60 mmHg; and Age ≥ 65 years.
The total score (0–5) stratifies patients into three risk classes with approximate 30-day mortality rates derived from the original BTS validation cohort: score 0–1 ≈ 1–3 % (low risk — outpatient care usually appropriate); score 2 ≈ 9–13 % (moderate risk — brief hospitalisation or close outpatient follow-up); score 3–5 ≈ 15–57 % (high risk — hospital admission required, ICU consideration for scores of 4–5).
Limitations: CURB-65 is a screening aid, not a definitive management protocol. It was validated primarily in hospitalised patients, may underestimate severity in immunocompromised individuals or those with atypical presentations, and does not capture comorbidities, oxygen saturation, or radiographic findings. Clinical judgment, local guidelines, and patient preferences must guide the final decision.
Frequently asked questions
C = Confusion (new disorientation); U = Urea > 7 mmol/L; R = Respiratory rate ≥ 30/min; B = Blood pressure (systolic < 90 mmHg or diastolic ≤ 60 mmHg); 65 = Age ≥ 65 years. Each criterion present scores 1 point.
A score of 2 indicates moderate risk (~9–13 % 30-day mortality) and warrants consideration of a short inpatient stay or intensively supervised outpatient care. Scores of 3 or above indicate high risk and generally require hospital admission; scores of 4–5 may warrant ICU-level care.
CRB-65 omits the Urea criterion (because urea measurement requires a blood test), using only Confusion, Respiratory rate, Blood pressure and Age ≥ 65. It is designed for use in primary care or community settings where laboratory tests may not be immediately available. CRB-65 scores of 0 indicate low risk; 1–2 moderate risk; 3–4 high risk.
TG we-Calculate Editorial Team. (2026). CURB-65 Calculator — Pneumonia Severity Score [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/curb-calculator
TG we-Calculate Editorial Team. "CURB-65 Calculator — Pneumonia Severity Score." TG we-Calculate. 2026. https://we-calculate.com/calculator/curb-calculator.
TG we-Calculate Editorial Team, "CURB-65 Calculator — Pneumonia Severity Score," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/curb-calculator
@misc{wecalculate_curb_calculator, title = {CURB-65 Calculator — Pneumonia Severity Score}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/curb-calculator}}, year = {2026}, note = {TG we-Calculate} }
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