BUN/creatinine ratio calculator
Work out your BUN:creatinine ratio — a quick pointer to whether a raised BUN is likely from dehydration or something in the kidney itself. Enter BUN and creatinine in mg/dL, or urea and creatinine in SI units and this tool converts them to the standard ratio.
Your privacy: this calculator runs entirely in your browser — nothing you type is sent anywhere. It's the same on-device principle Quanome is built on.
Educational reference only — not medical advice. The BUN:creatinine ratio is a pattern clue read with the actual BUN, creatinine, eGFR, and your hydration — not a diagnosis on its own. Reference ranges vary by lab.
## What the ratio means
| BUN/creatinine ratio | Category |
| --- | --- |
| < 10 : 1 | Low (intrinsic renal, low protein, liver, overhydration) |
| 10 : 1 – 20 : 1 | Normal |
| > 20 : 1 | High (pre-renal — often dehydration or GI bleed) |
A **high** ratio suggests a pre-renal cause, where BUN climbs faster than creatinine — classically **dehydration**. A **low** ratio points the other way, toward intrinsic kidney issues, low protein intake, or liver disease. Ranges vary between labs, so read your value against your own report.
## The formula
- **BUN/creatinine ratio = BUN ÷ creatinine** (both in mg/dL). The result is unitless.
- **SI units:** if your lab uses urea (mmol/L) and creatinine (µmol/L), convert first — BUN (mg/dL) = urea × 2.8, creatinine (mg/dL) = creatinine ÷ 88.4 — then divide. This tool does that for you so the number lands on the familiar 10–20 scale rather than the raw urea:creatinine ratio, which uses a different range.
## The rest of your kidney panel
The ratio is only a pointer — read it with the markers it comes from:
- **BUN & creatinine ratio, explained** — what the pattern means in depth: [what your BUN/creatinine ratio means](/blog/what-your-bun-creatinine-ratio-means/).
- **Creatinine & eGFR** — the core kidney-function readout: [what your creatinine & eGFR kidney results mean](/blog/what-your-creatinine-egfr-kidney-results-mean/).
- **Electrolytes & acid–base** — on the same metabolic panel; try the [anion gap calculator](/tools/anion-gap-calculator/) and the [corrected calcium calculator](/tools/corrected-calcium-calculator/).
## Track your kidney markers over time — privately
A single ratio is a snapshot; the value is in the **trend**. [Quanome](/) pulls your labs, Apple Health, and even your DNA into one private timeline on your device — parsed locally, never uploaded — with an AI coach that reads your kidney panel in whichever units you use.
Track your kidney markers over time, privately
Quanome unifies your labs, Apple Health, and DNA into one private, on-device timeline — in your units, with an AI coach. Free on the App Store and Google Play.
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