eGFR Calculator — Kidney Function
Calculate eGFR (estimated Glomerular Filtration Rate) using the 2021 CKD-EPI equation. Determine your CKD stage and kidney health from serum creatinine.
Medical Disclaimer: This calculator is for educational purposes only. Do not use it for self-diagnosis or treatment decisions. Consult your healthcare provider for interpretation of kidney function results.
Estimated GFR (eGFR)
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CKD Stages by eGFR
G1≥90Normal or high (with kidney damage markers)
G260–89Mildly decreased
G3a45–59Mildly to moderately decreased
G3b30–44Moderately to severely decreased
G415–29Severely decreased — nephrology referral recommended
G5<15Kidney failure — dialysis or transplant
Source: 2021 CKD-EPI equation (race-free). Reference: KDIGO Clinical Practice Guidelines 2024.
Frequently Asked Questions
- eGFR (estimated Glomerular Filtration Rate) estimates how well your kidneys filter waste from the blood. It's expressed in mL/min/1.73m² (milliliters of blood filtered per minute, normalized to body surface area). A normal eGFR is 90 or above. eGFR is the primary test used to diagnose and stage Chronic Kidney Disease (CKD).
- This calculator uses the 2021 CKD-EPI Creatinine Equation, which is the current gold-standard recommended by KDIGO (Kidney Disease: Improving Global Outcomes) and NKF (National Kidney Foundation). The 2021 equation is race-free, replacing the older 2009 version that included a race coefficient. It's more equitable and performs similarly in terms of accuracy.
- G1: eGFR ≥90 — Normal or high (with kidney damage markers) · G2: 60–89 — Mildly decreased · G3a: 45–59 — Mildly to moderately decreased · G3b: 30–44 — Moderately to severely decreased · G4: 15–29 — Severely decreased · G5: <15 — Kidney failure (dialysis or transplant needed).
- Normal serum creatinine: men 0.7–1.3 mg/dL, women 0.5–1.1 mg/dL. Creatinine is a waste product from muscle metabolism, filtered by the kidneys. Higher creatinine = lower kidney function. Muscle mass, diet (high meat intake), and hydration affect creatinine, which is why the eGFR formula adjusts for sex and age.
- Yes. eGFR naturally decreases with age (~1 mL/min/1.73m² per year after age 40). Acute illness, dehydration, NSAIDs, or contrast agents can temporarily reduce eGFR. Blood pressure control, diabetes management, ACE inhibitors/ARBs, and SGLT-2 inhibitors (empagliflozin, dapagliflozin) can slow the progression of CKD significantly.
- eGFR typically declines with age: Age 20–29: avg ~116 · 30–39: avg ~107 · 40–49: avg ~99 · 50–59: avg ~93 · 60–69: avg ~85 · 70–79: avg ~75 · 80+: avg ~65. An eGFR above 60 with no other markers of kidney disease is generally not considered CKD in older adults.
- Referral to a nephrologist is typically recommended when eGFR falls below 30 (Stage G4), or earlier if: eGFR is declining rapidly (>5 mL/min/1.73m² per year), significant proteinuria is present, blood pressure is difficult to control, or the cause of CKD is unclear. Early referral improves outcomes.
- No. This calculator is for informational purposes only. eGFR is only one component of kidney disease assessment. Diagnosis of CKD requires two separate tests more than 90 days apart plus clinical evaluation including urine albumin-to-creatinine ratio, imaging, and patient history. Always consult a healthcare provider for interpretation.