BUN/Creatinine Ratio Calculator

Calculate the blood urea nitrogen to creatinine ratio to evaluate azotemia.

Aug 31, 2026 Renal #renal-function #bun #creatinine #azotemia

Calculate

All fields required unless noted

BUN (mg/dL)

Serum creatinine (mg/dL)

Calculating...

Enter your values and press Calculate to see the result.

Reference Ranges Used

BUN/Creatinine Ratio - Adult 10–20 ratio

Formula & Clinical Notes

Formula

BUN/Creatinine Ratio = BUN (mg/dL) / SCr (mg/dL)

Clinical Notes

A normal BUN/creatinine ratio is approximately 10-15:1. A ratio above 20:1 suggests a prerenal component (dehydration, volume depletion, GI bleeding, catabolic states); a ratio below 10:1 suggests reduced urea production (liver disease, low protein intake). The ratio uses BUN in mg/dL and serum creatinine in mg/dL.

Sources

Clinical Methods — BUN and Creatinine
StatPearls — Renal Function Tests