GFR Calculator
Calculate your Glomerular Filtration Rate (GFR) to assess kidney function. Our calculator uses multiple formulas including CKD-EPI, MDRD, and Cockcroft-Gault equations.
Patient Information
Race affects GFR calculation in CKD-EPI equation
Normal range: 0.6-1.2 mg/dL (53-106 μmol/L)
Optional: Required only for Cockcroft-Gault equation
GFR Results
Understanding GFR
What is GFR?
Glomerular Filtration Rate (GFR) measures how well your kidneys filter blood. It's the best overall indicator of kidney function and is used to diagnose and monitor chronic kidney disease (CKD).
Why is GFR Important?
GFR helps doctors detect kidney disease early, monitor progression, adjust medication dosages, and determine when treatments like dialysis or transplant may be needed.
GFR Calculation Methods
- CKD-EPI: Most accurate for adults, recommended by guidelines
- MDRD: Older formula, less accurate at higher GFR values
- Cockcroft-Gault: Estimates creatinine clearance, requires weight
Factors Affecting GFR
- Age (decreases ~1 mL/min/1.73m² per year after 30)
- Gender (typically lower in females)
- Race/ethnicity
- Muscle mass and diet
- Medications and health conditions
Chronic Kidney Disease Stages
Stage 1
≥90 mL/min/1.73m²
Normal or high kidney function with kidney damage
Stage 2
60-89 mL/min/1.73m²
Mild decrease in kidney function
Stage 3
30-59 mL/min/1.73m²
Moderate decrease in kidney function
Stage 4
15-29 mL/min/1.73m²
Severe decrease in kidney function
Stage 5
<15 mL/min/1.73m²
Kidney failure
Stage-Specific Recommendations
Monitor and treat underlying conditions, lifestyle modifications
Nephrology referral, manage complications, slow progression
Prepare for renal replacement therapy, manage complications
Dialysis or kidney transplant, supportive care
Example Calculation
65-year-old African American Male • Creatinine: 1.5 mg/dL
CKD-EPI Calculation:
• Age: 65 years
• Gender: Male
• Race: Black/African American
• Serum creatinine: 1.5 mg/dL
• eGFR: 63 mL/min/1.73m²
Interpretation:
• CKD Stage: 2 (Mild decrease)
• Function: Mildly decreased
• Risk: Low to moderate
• Recommendation: Monitor annually, lifestyle modifications
Frequently Asked Questions
How accurate are GFR calculations?
GFR calculations are estimates with limitations. CKD-EPI is most accurate for adults but may be less reliable in certain populations (very elderly, muscular, or malnourished patients). Direct measurement requires specialized testing.
What can affect my GFR results?
Factors include dehydration, recent high-protein meals, intense exercise, certain medications, muscle mass, and acute illness. For accurate results, avoid these factors before testing when possible.
When should I be concerned about my GFR?
GFR below 60 mL/min/1.73m² for more than 3 months indicates chronic kidney disease. However, always consult with your healthcare provider for proper interpretation and follow-up recommendations.