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CURB-65 Calculator

CURB-65 is a five-item severity score for adults with community-acquired pneumonia. Each letter is one feature worth a point; the total was designed to help judge how sick a patient is and what level of care and monitoring the illness may need, alongside clinical assessment.

Formula: C confusion (new) · U urea raised — urea above 7 mmol/L (BUN above ~19 mg/dL) · R respiratory rate 30/min or more · B blood pressure — systolic below 90 or diastolic 60 or below · 65 age 65 or over. One point each.

Enter the values or tick the options above — the result updates automatically.

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How to interpret the result

ScoreApproximate 30-day mortality in the original studies
0~0.6%
1~2.7%
2~6.8%
3~14.0%
4~27.8%
5~27.8%

In broad terms the original work grouped 0–1 as low risk, 2 as intermediate, and 3–5 as high. These percentages describe groups of patients in past studies — they are not a prediction for any individual, and modern outcomes vary with setting and treatment.

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Frequently asked questions

What does the "U" in CURB-65 use — urea or BUN?

The original score uses blood urea above 7 mmol/L. In laboratories reporting BUN (urea nitrogen) in mg/dL, the roughly equivalent threshold is about 19–20 mg/dL.

Is there a version without blood tests?

Yes — CRB-65 drops the urea item and is used in community settings where blood results are not available. Its groupings differ, so the two scores are not interchangeable.

Does CURB-65 decide admission on its own?

No. It is one input alongside oxygen saturation, the overall clinical picture, other conditions, and the patient's circumstances and wishes.

Educational use only. This calculator is an aid to learning and does not replace clinical judgment, local reference ranges, or specialist advice. Always interpret a result alongside the patient, the full laboratory picture, and your laboratory's own reference ranges.