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GFR Calculator

Calculate estimated Glomerular Filtration Rate (eGFR) using multiple validated equations including CKD-EPI 2021. Assess kidney function and chronic kidney disease staging.

Patient Information

Used for CKD-EPI 2009 equation. CKD-EPI 2021 is race-free.

Normal ranges: 0.6-1.3 mg/dL

Medical Disclaimer

This calculator is for educational purposes only. Always consult healthcare professionals for medical advice and interpretation of results.

GFR Assessment Results

Estimated GFR (CKD-EPI 2021)

74 mL/min/1.73m²

Race-free equation (recommended)

CKD Stage 2

Mildly decreased kidney function

Risk level: low

Kidney Function

62%

of normal

BMI

22.9

kg/m²

Input Summary
Age: 50 years
Gender: male
Weight: 70 kg
Height: 175 cm
Creatinine: 1.2 mg/dL
Race: Non-Black


What is GFR Calculator?

Understanding Glomerular Filtration Rate (GFR)

Glomerular Filtration Rate (GFR) is the best overall indicator of kidney function. It measures how much blood the kidneys filter each minute. GFR is estimated using serum creatinine levels along with age, gender, and other factors. Understanding your GFR helps assess kidney health and chronic kidney disease risk.

What is GFR?

  • Normal Function: Healthy kidneys filter 90-120 mL/min/1.73m² of blood
  • Filtration Process: Kidneys remove waste products and excess water from blood
  • Age-Related Decline: GFR naturally decreases by ~1 mL/min/1.73m² per year after age 30
  • Individual Variation: Normal ranges vary based on age, gender, and body size

GFR Calculation Methods

CKD-EPI 2021 (Recommended)

Most accurate current equation. Removes racial bias present in older formulas. Recommended by major nephrology organizations.

CKD-EPI 2009

Widely used equation that includes race as a factor. Being phased out in favor of the race-free 2021 version.

MDRD

Older equation that tends to underestimate GFR at higher levels. Less accurate than CKD-EPI equations.

Cockcroft-Gault

Estimates creatinine clearance rather than GFR. Still used for drug dosing but less accurate for staging CKD.

Chronic Kidney Disease (CKD) Stages

Stage 1 (GFR ≥90): Normal or high function with kidney damage markers
Stage 2 (GFR 60-89): Mildly decreased function with kidney damage
Stage 3a (GFR 45-59): Mild to moderate decrease - monitor closely
Stage 3b (GFR 30-44): Moderate to severe decrease - specialist referral
Stage 4 (GFR 15-29): Severe decrease - prepare for treatment
Stage 5 (GFR <15): Kidney failure - dialysis or transplant needed

Risk Factors for Kidney Disease

  • Diabetes: Leading cause of kidney disease; high blood sugar damages kidneys
  • Hypertension: High blood pressure damages kidney blood vessels
  • Family History: Genetic predisposition increases risk
  • Age: Risk increases with age, especially after 60
  • Cardiovascular Disease: Heart disease and kidney disease often coexist
  • Obesity: Increases risk of diabetes and hypertension
  • Smoking: Damages blood vessels and accelerates kidney damage

Limitations of GFR Estimation

  • Creatinine Dependence: Based on creatinine levels, which can be affected by muscle mass
  • Less Accurate at Higher GFRs: Estimates become less precise above 60 mL/min/1.73m²
  • Acute Changes: May not reflect rapid changes in kidney function
  • Muscle Mass Effects: Very muscular or frail individuals may have inaccurate estimates
  • Laboratory Variation: Different labs may have slightly different creatinine assays

When to Seek Medical Attention

GFR <60: Should prompt further evaluation and possible specialist referral
Rapid Decline: Drop of >25% in GFR over months to years
Risk Factors Present: Diabetes, hypertension, or family history with any GFR decline
Symptoms: Fatigue, swelling, changes in urination, or other kidney-related symptoms


FAQ - GFR Calculator

GFR measures how well your kidneys filter blood. Normal is 90-120 mL/min/1.73m². A GFR of 60 or higher is generally considered normal if you don't have kidney damage. Below 60 may indicate chronic kidney disease. Below 15 indicates kidney failure requiring dialysis or transplant.