Calculated Glomerular Filtration Rate

eGFR Calculator (CKD-EPI 2021)

Male Female

Your Estimated GFR

mL/min/1.73m²

function calculateGFR() { var scr = parseFloat(document.getElementById('creatinine').value); var age = parseInt(document.getElementById('age').value); var gender = document.getElementById('gender').value; var resultBox = document.getElementById('gfr-result-box'); var valueDisplay = document.getElementById('gfr-value'); var stageDisplay = document.getElementById('gfr-stage'); var descDisplay = document.getElementById('gfr-desc'); if (isNaN(scr) || isNaN(age) || scr <= 0 || age = 90) { stage = 'Stage 1'; bgColor = '#27ae60'; desc = 'Normal or high kidney function. Monitor if other signs of kidney damage are present.'; } else if (roundedGFR >= 60) { stage = 'Stage 2'; bgColor = '#82bf45'; desc = 'Mildly decreased kidney function. Often normal for elderly individuals.'; } else if (roundedGFR >= 45) { stage = 'Stage 3a'; bgColor = '#f1c40f'; textColor = '#000000'; desc = 'Mildly to moderately decreased kidney function.'; } else if (roundedGFR >= 30) { stage = 'Stage 3b'; bgColor = '#e67e22'; desc = 'Moderately to severely decreased kidney function. Seek medical advice.'; } else if (roundedGFR >= 15) { stage = 'Stage 4'; bgColor = '#e74c3c'; desc = 'Severely decreased kidney function. High risk of progression to failure.'; } else { stage = 'Stage 5'; bgColor = '#c0392b'; desc = 'Kidney failure (End-stage renal disease). Dialysis or transplant may be necessary.'; } stageDisplay.innerText = stage + ' : CKD Classification'; stageDisplay.style.backgroundColor = bgColor; stageDisplay.style.color = textColor; descDisplay.innerText = desc; resultBox.scrollIntoView({ behavior: 'smooth' }); }

The Estimated Glomerular Filtration Rate (eGFR) is the most reliable metric used by healthcare professionals to determine how well your kidneys are filtering waste from your blood. Unlike a simple creatinine test, eGFR considers biological factors to provide a more accurate picture of renal health.

The CKD-EPI 2021 Equation

This calculator utilizes the CKD-EPI 2021 (Chronic Kidney Disease Epidemiology Collaboration) equation. As of 2021, the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) recommended this race-free calculation to ensure more equitable and accurate diagnostics for all patients.

Interpreting Your GFR Results

GFR results are generally categorized into five stages of Chronic Kidney Disease (CKD):

• Stage 1 (90+): Normal kidney function, but some evidence of damage may exist.
• Stage 2 (60-89): Mild loss of kidney function.
• Stage 3 (30-59): Moderate loss of kidney function; typically split into 3a and 3b.
• Stage 4 (15-29): Severe loss of kidney function.
• Stage 5 (Below 15): Kidney failure; often requires dialysis or a transplant.

Why Creatinine Alone Isn't Enough

Serum creatinine is a waste product from muscle breakdown. Because muscle mass varies significantly based on age and biological sex, a "normal" creatinine level for a 25-year-old male might indicate severe kidney disease in an 80-year-old female. The GFR calculation normalizes these variables to provide a standardized score based on body surface area (1.73m²).

Example Calculation

Consider a 60-year-old male with a serum creatinine of 1.4 mg/dL. While 1.4 might only be slightly outside the "normal" range on a lab report, his eGFR would be approximately 58 mL/min/1.73m², placing him in Stage 3a Chronic Kidney Disease. This highlights the importance of using the eGFR rather than looking at creatinine in isolation.

Important Disclaimer

This tool is for informational purposes only and does not constitute medical advice. GFR can be temporarily affected by dehydration, high protein intake, or certain medications. Always consult with a licensed physician or nephrologist to discuss your lab results and kidney health.

Frequently Asked Questions

How can I improve my GFR?
While damaged kidney tissue often cannot be "healed," you can protect your remaining function by managing blood pressure, controlling blood sugar levels, reducing salt intake, and avoiding NSAIDs (like ibuprofen).

Is a higher GFR better?
Yes. A higher number indicates that your kidneys are filtering more blood per minute. A GFR above 60 is generally considered to be in the normal to near-normal range for most adults.