BUN to Creatinine Ratio Calculator – Kidney Health Assessment

Your kidneys play a vital role in filtering waste and maintaining your body’s balance of electrolytes, fluids, and proteins. One of the most common ways doctors assess kidney function is through the BUN to Creatinine Ratio.

A BUN to Creatinine Ratio Calculator helps you quickly understand this important health indicator by comparing Blood Urea Nitrogen (BUN) and Creatinine levels in your blood. The results can indicate how well your kidneys are working and whether further medical evaluation is needed.

What is BUN to Creatinine Ratio?

The BUN to Creatinine Ratio is a simple calculation that compares the amount of urea nitrogen in your blood (BUN) to the amount of creatinine.

• BUN (Blood Urea Nitrogen): Urea is a waste product formed in the liver when your body breaks down protein. It is excreted by the kidneys. Normal range: 7–20 mg/dL.
  
• Creatinine: A waste product from muscle metabolism, filtered by the kidneys. Normal range: 0.6–1.3 mg/dL.
  

By calculating the ratio between BUN and Creatinine, doctors can detect:

• Kidney function abnormalities
  
• Dehydration
  
• Heart failure
  
• Urinary tract obstructions
  

Why It’s Useful

• Helps detect early kidney problems.
  
• Assists in differentiating between pre-renal, renal, and post-renal causes of kidney dysfunction.
  

Provides a quick screening tool for routine health checkups.

How the Calculator Works (Step by Step)

Step 1: Enter Blood Urea Nitrogen (BUN)

This value is measured in mg/dL from your blood test. Example: 18 mg/dL.

Step 2: Enter Creatinine

Creatinine value is also measured in mg/dL. Example: 1.0 mg/dL.

Step 3: The Calculator Applies the Formula

The ratio is calculated using the standard formula:

BUN to Creatinine Ratio = BUN ÷ Creatinine

Step 4: Interpretation of Results

The calculator then interprets the ratio based on standard clinical ranges:

Step 5: Results Are Displayed

You will see:

• Your calculated BUN:Cr ratio
  
• Kidney health assessment (normal, high, or low)
  
• Optional medical advice: “Consult your doctor if your ratio is abnormal.”

Formula

1. BUN to Creatinine Ratio
   

BUN to Creatinine Ratio = Blood Urea Nitrogen (mg/dL) ÷ Creatinine (mg/dL)

2. Example Calculation
   

• BUN = 18 mg/dL
  
• Creatinine = 1 mg/dL
  

BUN:Cr Ratio = 18 ÷ 1 = 18

Interpretation: Normal ratio (10–20:1).

Real-Life Examples

Example 1 – Normal

• BUN: 15 mg/dL
  
• Creatinine: 1.0 mg/dL
  

Ratio = 15 ÷ 1 = 15 → Normal

Example 2 – High Ratio (Dehydration)

• BUN: 35 mg/dL
  
• Creatinine: 1.2 mg/dL
  

Ratio = 35 ÷ 1.2 ≈ 29 → High, may indicate dehydration

Example 3 – Low Ratio (Kidney Damage)

• BUN: 8 mg/dL
  
• Creatinine: 1.0 mg/dL
  

Ratio = 8 ÷ 1 = 8 → Low, possible kidney or liver issues