GFR Calculator

- May 10, 2025
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Calculate estimated Glomerular Filtration Rate (eGFR) using the MDRD or CKD-EPI equations. GFR measures how well your kidneys filter blood and helps detect kidney disease.

Patient Information

Laboratory Values

Advanced Options

About GFR and Kidney Function

Glomerular Filtration Rate (GFR) is the best overall measure of kidney function. It estimates how much blood passes through the glomeruli (tiny filters in kidneys) each minute. A declining GFR indicates worsening kidney function.

GFR Classification and CKD Stages
GFR (mL/min/1.73m²) CKD Stage Kidney Function
≥90 Stage 1 (with other evidence of kidney damage) Normal or High
60-89 Stage 2 (with other evidence of kidney damage) Mildly Decreased
45-59 Stage 3a Mildly to Moderately Decreased
30-44 Stage 3b Moderately to Severely Decreased
15-29 Stage 4 Severely Decreased
<15 Stage 5 Kidney Failure
Calculation Methods
  • CKD-EPI Equation (2009): The most accurate method for estimating GFR, especially for higher GFR values (>60 mL/min/1.73m²). Recommended for general clinical use.
  • MDRD Equation (4-variable): An older formula that may underestimate GFR in healthier individuals with values >60 mL/min/1.73m².
Important Notes
  • This calculator provides an estimate of GFR based on serum creatinine. For more accurate kidney function assessment, consult with a healthcare provider.
  • GFR calculations are less reliable at extremes of age and body size.
  • A single GFR measurement should not be used to diagnose kidney disease. Persistent abnormalities for >3 months are needed for chronic kidney disease diagnosis.
  • Additional tests (e.g., urine albumin-to-creatinine ratio) may be needed to fully assess kidney health.

Understanding the GFR Calculator

The GFR Calculator is a helpful tool that estimates your Glomerular Filtration Rate (eGFR). This measurement is crucial for understanding how well your kidneys are working. The calculator uses two common equations: MDRD and CKD-EPI. Monitoring your GFR can help in detecting kidney disease early, making it an essential part of Health assessments for many individuals.

Why GFR Matters for Your Health

GFR is a key indicator of kidney function. By calculating your GFR, you can get insights into your overall kidney health. Here are some important points about GFR:

  • Normal GFR indicates healthy kidneys.
  • A declining GFR may signal kidney issues.
  • Regular monitoring can help assess kidney function over time.

How to Use the GFR Calculator

Using the GFR Calculator is straightforward. You will need to provide some personal information like age, gender, and race. Additionally, you'll be asked to enter your serum creatinine levels. Based on your inputs, the calculator will estimate your GFR and provide information about your kidney function.

What Inputs Are Required?

To get an accurate result from the GFR Calculator, a few key inputs are necessary. You will need the following:

  • Your age (between 18 and 120 years).
  • Your gender (male or female).
  • Your race (Non-Black or Black).
  • Your serum creatinine level (in mg/dL or μmol/L).

Understanding Your Results

Once you get your results, it will show your estimated GFR alongside details about your kidney function. The results will also indicate the stage of Chronic Kidney Disease (CKD) if applicable. This helps in understanding what your GFR means regarding your kidney health.

Interpreting GFR Levels

GFR levels help determine the stage of kidney function. Here’s a breakdown of GFR classifications:

  • ≥90 mL/min: Normal or High (Stage 1)
  • 60-89 mL/min: Mildly Decreased (Stage 2)
  • 30-44 mL/min: Moderately to Severely Decreased (Stage 3)
  • 15-29 mL/min: Severely Decreased (Stage 4)
  • <15 mL/min: Kidney Failure (Stage 5)

Factors Affecting GFR Estimates

There are several factors that can influence GFR estimates. Age, muscle mass, and hydration levels are significant. It’s also essential to consult with a healthcare provider if there are any concerns, as a single measurement may not be enough to fully assess kidney health.

Limitations and Further Testing

While the GFR Calculator provides useful estimates, it has limitations. Persistent issues over time are needed to diagnose chronic kidney disease. For a complete evaluation, additional tests may be necessary. Always discuss your results with a healthcare professional for the best guidance on your kidney health.