GFR Calculator (Glomerular Filtration Rate)

GFR Calculator (Glomerular Filtration Rate). Enter your serum creatinine, age, and sex to estimate your Glomerular Filtration Rate (eGFR) using the CKD-EPI Creatinine (2021) equation. Your results include your eGFR value in mL/min/1.73m² and the corresponding CKD stage, helping you understand your current level of kidney function. Also try the Creatinine Clearance (Cockcroft-Gault) Calculator.

Results

Estimated GFR (eGFR)

CKD Stage

Stage Description

Kidney Function

Results Table

What is GFR and why does it matter?

Glomerular Filtration Rate (GFR) measures how well your kidneys filter waste from the blood each minute. It is considered the best overall index of kidney function. A normal GFR is approximately 90–120 mL/min/1.73m², and lower values indicate reduced kidney function.

What equation does this calculator use?

This calculator uses the CKD-EPI Creatinine (2021) equation, which was updated to remove race as a variable. It is recommended by the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) as the standard for estimating GFR in adults.

What are the five stages of kidney disease?

Stage 1 (GFR ≥90) indicates normal or high function with possible kidney damage. Stage 2 (GFR 60–89) is mildly decreased function. Stage 3 (GFR 30–59) is moderately decreased. Stage 4 (GFR 15–29) is severely decreased. Stage 5 (GFR <15) is kidney failure requiring dialysis or transplant.

Is it CKD if my eGFR is below 60?

An eGFR below 60 for three months or more, or the presence of kidney damage markers (such as protein in the urine), generally indicates Chronic Kidney Disease (CKD). A single low eGFR reading should be confirmed with follow-up testing by your healthcare provider.

How is serum creatinine measured?

Serum creatinine is measured through a simple blood test ordered by your doctor. Creatinine is a waste product from normal muscle metabolism, and the kidneys filter it from the blood — so higher creatinine levels often reflect reduced kidney function.

Can I use this calculator if I am under 18?

No. The CKD-EPI equation is validated for adults aged 18 and older. For children and adolescents, different pediatric GFR equations (such as the Bedside Schwartz equation) are used. Please consult a healthcare provider for pediatric kidney assessments.

Does a low eGFR always mean I have kidney disease?

Not necessarily on a single reading. Temporary factors such as dehydration, intense exercise, or certain medications can transiently lower eGFR. Kidney disease is typically diagnosed when eGFR stays below 60 for three months or more, or when other markers of kidney damage are present.

What should I do if my eGFR result is abnormal?

If your eGFR result is below 60 or you are concerned about your kidney health, speak with your doctor or a nephrologist. Early detection and lifestyle changes — such as controlling blood pressure, managing blood sugar, and staying hydrated — can help slow the progression of kidney disease.