BUN to Creatinine Ratio Calculator

How it is calculated

BUN:creatinine ratio = BUN (mg/dL) ÷ creatinine (mg/dL).

What your result means

• BUN moves with hydration, protein intake and some medications, so the ratio is read alongside each value and your situation.
• Your own lab's printed range and your clinician's read of your history come first; this calculator is educational and is not a diagnosis.

Test the inputs

The Metabolic and insulin panel measures the values this calculator uses. Related: bun, creatinine, egfr.

Common questions

How is the BUN to creatinine ratio calculated?

BUN in mg/dL divided by creatinine in mg/dL, both from the same blood draw.

What can raise the ratio?

Dehydration and a high protein intake are common reasons, among others a clinician considers.

Does a normal ratio mean my kidneys are fine?

Not on its own. Kidney function is judged with eGFR, urine tests and results over time.

References

1. Blood urea nitrogen and serum creatinine. Physiology and interpretations. Urology, 1975.
2. J-shaped association between blood urea nitrogen-to-creatinine ratio and mortality in critically ill patients with acute pancreatitis: a retrospective cohort study using the MIMIC-IV database. Eur J Med Res, 2025.