GFR Calculator

Use this free GFR calculator to estimate your glomerular filtration rate (eGFR) using the race-neutral CKD-EPI 2021 clinical standard equation to assess kidney function and CKD stage.

How to use this calculator

1. Select your gender and enter your age.
2. Enter your serum creatinine level from your blood test results (mg/dL).
3. View estimated GFR and Chronic Kidney Disease (CKD) stage classification.

Formula & method

CKD-EPI 2021 eGFR Refined Equation

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × (1.012 if female)

κ = 0.7 (female), 0.9 (male). α = −0.241 (female), −0.302 (male). Scr = Serum creatinine.

Example

Male age 50, Scr 1.0 mg/dL → eGFR ≈ 91 mL/min/1.73m² (Normal / Stage G1).

Key insights

• The National Kidney Foundation recommends the CKD-EPI 2021 equation because it does not include a race coefficient.
• An eGFR of 60 mL/min/1.73m² or higher is generally considered normal if no other signs of kidney damage exist.
• eGFR naturally decreases gradually with age, even in individuals without active kidney disease.

How to interpret your result

eGFR Value

Flow rate of filtered fluid through the kidney per minute normalized to body surface area.

CKD Stage G1 to G5

Clinical severity ranking ranging from normal (G1) to kidney failure (G5).

Frequently asked questions

What serum creatinine unit is used?

This calculator uses mg/dL. If your lab results are in µmol/L, divide by 88.4 to convert to mg/dL.

When should I see a doctor?

Any persistent eGFR below 60 mL/min/1.73m² should be evaluated by a medical professional.

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