GFR Calculator - CKD-EPI Glomerular Filtration Rate

About the GFR Calculator

This GFR (glomerular filtration rate) calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation to estimate kidney function. It is one of the most accurate methods for assessing renal function in adults. The calculator takes into account age, gender, serum creatinine level, and race to provide an estimated GFR value along with the corresponding CKD stage.

Formula Used

CKD-EPI Equation:
Female, Cr ≤ 0.7: GFR = 144 × (Cr/0.7)^−0.329 × 0.993^Age
Female, Cr > 0.7: GFR = 144 × (Cr/0.7)^−1.209 × 0.993^Age
Male, Cr ≤ 0.9: GFR = 141 × (Cr/0.9)^−0.411 × 0.993^Age
Male, Cr > 0.9: GFR = 141 × (Cr/0.9)^−1.209 × 0.993^Age
Multiply by 1.159 if African American.

What do the CKD stages mean?

CKD stages range from 1 to 5. Stage 1 (GFR ≥ 90) indicates normal kidney function with other signs of kidney damage. Stage 2 (60–89) is mild decline. Stage 3a (45–59) and 3b (30–44) indicate moderate decline. Stage 4 (15–29) is severe decline, and Stage 5 (< 15) is kidney failure requiring dialysis or transplant.

How accurate is the CKD-EPI equation?

The CKD-EPI equation is more accurate than the older MDRD equation, especially at higher GFR values. It was developed from a large, diverse population and has been validated across multiple ethnic groups. However, it remains an estimate — the gold standard for measuring GFR involves exogenous filtration markers like iohexol or inulin.

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