Urea mmol/L → BUN mg/dL
Convert SI urea (mmol/L) to US blood urea nitrogen (BUN, mg/dL)
Sources last checked: 2026-10-13
Urea mmol/L → BUN mg/dL
Convert SI urea (mmol/L) to US blood urea nitrogen (BUN, mg/dL)
Uses the AMA factor for urea nitrogen (mg/dL × 0.357 = mmol/L). Not for urea reported in mg/dL — use the Harnstoff (mg/dL) → BUN converter.
What is the Urea mmol/L → BUN mg/dL?
UK and many European labs report urea in mmol/L, while US literature uses blood urea nitrogen (BUN) in mg/dL — the mass of nitrogen only. Since each urea molecule carries two nitrogen atoms, urea and urea nitrogen have the same molar concentration, and the AMA SI table factor 0.357 (BUN mg/dL → mmol/L) converts directly.
When to use it
- Applying US-derived scores that use BUN (e.g. BUN thresholds in pneumonia or GI bleeding scores)
- Calculating a BUN/creatinine ratio from SI results
- Reading US literature with European lab values
When not to use it
- Urea reported in mg/dL (Germany, Austria, Turkey) — use the Harnstoff mg/dL → BUN converter
- CURB-65, which is defined on urea in mmol/L (> 7 mmol/L) — no conversion needed
How it is calculated
BUN (mg/dL) = urea (mmol/L) ÷ 0.357 (≈ × 2.8) One urea molecule carries two nitrogen atoms (28 g N per mol), so urea and urea-nitrogen are the same in mmol/L.
Clinical pearls and limitations
- Uses the AMA factor for urea nitrogen (mg/dL × 0.357 = mmol/L). Not for urea reported in mg/dL — use the Harnstoff (mg/dL) → BUN converter.
- Quick check: urea mmol/L × 2.8 ≈ BUN mg/dL.
- 7 mmol/L urea ≈ 19.6 mg/dL BUN.
- BUN in mmol/L is numerically the same as urea in mmol/L.
Frequently asked questions
How do I convert urea mmol/L to BUN?
Divide by 0.357 (≈ multiply by 2.8). Example: 10 mmol/L urea = 28 mg/dL BUN.
Is BUN the same as urea?
Not in mass units: BUN counts only the nitrogen in urea. In mmol/L the numbers are the same.
What is a normal BUN?
Typically about 7–20 mg/dL, corresponding to roughly 2.5–7 mmol/L urea; ranges vary by lab.
Evidence and guidelines
Have a follow-up question?
Medelix answers clinical questions from current guidelines and studies — every statement with its source.
Ask Medelix about the Urea mmol/L → BUN mg/dLRelated calculators
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<p><a href="https://medelix.ai/en/calculators/urea-mmol-l-to-bun">Urea mmol/L → BUN mg/dL calculator by Medelix</a></p>For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.