eGFR Kidney Function Calculator

What Is eGFR? The estimated Glomerular Filtration Rate (eGFR) measures how well your kidneys filter waste from the blood. The glomeruli are tiny filtering units inside the kidneys — a healthy adult has about 1 million per kidney. eGFR is reported in mL/min/1.73m² — the volume of blood filtered per minute, normalized to standard body surface area. A healthy young adult typically has an eGFR of 90–120 mL/min/1.73m².

The CKD-EPI Equation (2021) The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) published an updated race-free equation in 2021. This is now the recommended standard in the United States, Canada, and much of Europe. eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age For females, multiply by 1.012. Where: Scr = serum creatinine (mg/dL), κ = 0.7 (females) or 0.9 (males), α = −0.241 (females) or −0.302 (males).

CKD Stages by eGFR Normal or high (Stage G1): eGFR ≥ 90 — kidney damage may be present but GFR is normal. Mildly decreased (Stage G2): eGFR 60–89 — mild reduction; monitor annually. Mildly-moderately decreased (Stage G3a): eGFR 45–59 — refer to nephrology if other risk factors. Moderately-severely decreased (Stage G3b): eGFR 30–44 — nephrology referral recommended. Severely decreased (Stage G4): eGFR 15–29 — prepare for kidney replacement therapy. Kidney failure (Stage G5): eGFR < 15 — dialysis or transplant may be required.

What Is Creatinine? Creatinine is a waste product produced by muscle metabolism at a constant rate. Healthy kidneys filter it efficiently — high blood creatinine means the kidneys are not filtering well. Normal serum creatinine: 0.7–1.2 mg/dL (males), 0.5–1.0 mg/dL (females). Creatinine can be temporarily elevated by intense exercise, high meat intake, or dehydration. Cystatin C is an alternative marker that is less affected by muscle mass — sometimes used alongside creatinine.

Factors That Affect eGFR Age: eGFR naturally declines by about 1 mL/min/year after age 40. Muscle mass: very muscular individuals produce more creatinine and may have lower calculated eGFR. Pregnancy: eGFR rises during pregnancy due to increased renal blood flow. Medications: NSAIDs, ACE inhibitors, and certain antibiotics can temporarily reduce eGFR.

When to See a Doctor Single eGFR values should always be confirmed with repeat testing. eGFR below 60 on two measurements ≥ 3 months apart confirms chronic kidney disease. eGFR below 30 requires nephrology consultation. Below 15 may require transplant evaluation.

Disclaimer This calculator is for educational purposes only. Consult a licensed physician for medical evaluation.