---
title: BUN to Creatinine Ratio Calculator
type: tool
url: "https://www.test-well.com/tools/bun-creatinine-ratio-calculator"
date_published: 2026-10-12
free: true
---

# BUN to Creatinine Ratio Calculator

> Enter BUN and creatinine from the same metabolic panel and the calculator divides them. A ratio of about 10–20 is usual; above 20 means urea is rising faster than creatinine, as in dehydration, reduced kidney blood flow, a high-protein intake, gut bleeding or steroids; below 10 points to liver disease, low protein intake or a high creatinine from muscle. A clue to read with the eGFR, not a diagnosis.

## Key facts

| Fact | Value |
| --- | --- |
| Inputs | BUN · creatinine |
| Usual ratio | ≈ 10–20 |
| Read with | eGFR · hydration · diet |
| Cost | Free |

## For agents

See https://www.test-well.com/developers for the agent endpoints.

## Frequently asked questions

### What is a normal BUN to creatinine ratio?

About 10:1 to 20:1 when both are in mg/dL. Laboratories do not always print the ratio, and it is not a test result in itself — it is a comparison of two results that move for different reasons, so the absolute BUN, creatinine and eGFR are read first and the ratio second.

### What causes a high BUN to creatinine ratio?

Anything that raises urea faster than creatinine: dehydration or reduced blood flow to the kidneys (the classic 'prerenal' pattern), a high-protein diet or protein supplements, blood in the gut being digested, corticosteroids, heart failure, and urinary obstruction. Rehydration and a repeat panel sort out most outpatient cases.

### Can the ratio tell dehydration from kidney disease?

Only roughly. A high ratio with a normal creatinine favors dehydration or diet; both values high with a normal ratio favors the kidney itself. In hospital patients the ratio is notoriously unreliable because steroids, feeding, bleeding and liver disease change BUN on their own — which is why the eGFR and the clinical picture carry the decision.

## Related

- [bun](https://www.test-well.com/biomarkers/bun)
- [creatinine](https://www.test-well.com/biomarkers/creatinine)
- [egfr](https://www.test-well.com/biomarkers/egfr)
- [cystatin c](https://www.test-well.com/biomarkers/cystatin-c)
- [basic metabolic panel](https://www.test-well.com/tests/basic-metabolic-panel)
- [comprehensive metabolic panel](https://www.test-well.com/tests/comprehensive-metabolic-panel)
- [renal panel](https://www.test-well.com/tests/renal-panel)
- [kidney health panel](https://www.test-well.com/tests/kidney-health-panel)
- [cystatin c](https://www.test-well.com/tests/cystatin-c)

---

Canonical page: https://www.test-well.com/tools/bun-creatinine-ratio-calculator
Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt

Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.