Nephrology

eGFR Calculator (CKD-EPI 2021) and CKD Stage

Q: Why was race removed from the equation?

The race coefficient (1.16 for Black patients) overestimated GFR and delayed referral for transplantation. The 2021 version is more accurate without this coefficient and applies equally to all patients.

Q: When should cystatin C be used?

For borderline results (GFR 45-60 with no other markers of kidney damage), in patients with extreme muscle mass, and to refine CKD staging in older adults.

Q: At what GFR should a patient be referred to nephrology?

All patients with GFR < 30, rapid decline (> 5 mL/min/year), suspected glomerulonephritis, or significant albuminuria, per KDIGO guidance.

Estimates GFR and CKD stage (G1-G5) from serum creatinine, age, and sex

Primary source: Inker LA et al. N Engl J Med 2021; 385: 1737-1749. KDIGO 2024 CKD Guideline

Aleksandr A. Aulov, MD, internal medicine Last clinical review: April 28, 2026

Online calculation

Serum creatinine

µmol/L

Age

years

Sex

Albuminuria (for complete KDIGO staging)

Urine albumin-to-creatinine ratio (mg/g) or 24-hour excretion

About this score

CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) is the standard equation for estimating glomerular filtration rate (GFR) from serum creatinine. The 2021 version (Inker LA et al., NEJM 2021) removed the race coefficient, which previously overestimated GFR in Black patients and delayed referral for renal replacement therapy.

The equation uses creatinine, age, and sex. The result is GFR in mL/min/1.73 m². CKD stages per KDIGO 2024: G1 — ≥ 90 (normal or high, with markers of kidney damage); G2 — 60-89 (mildly decreased); G3a — 45-59; G3b — 30-44; G4 — 15-29 (preparation for renal replacement therapy); G5 — < 15 (renal replacement therapy or palliative care).

KDIGO 2024 recommends CKD-EPI 2021 as the standard equation. For borderline results (between G2 and G3a), CKD-EPI cystatin C can be used for confirmation. Risk of CKD progression is stratified using the KDIGO heat map (GFR × albuminuria).

When to use

Any assessment of kidney function in adults.
CKD staging and decisions on nephrology referral.
Dosing of renally cleared drugs.
Screening in diabetes, hypertension, cardiovascular disease, and geriatrics — at least annually.

Parameters in detail

Sex

Sex — used as a coefficient in the equation.

Clinical example

Case

68-year-old woman, type 2 diabetes for 12 years, hypertension. Serum creatinine 110 µmol/L. Urine albumin 250 mg/g creatinine.

Calculation

By CKD-EPI 2021, for a 68-year-old woman with creatinine 110 µmol/L, GFR ≈ 47 mL/min/1.73 m².

Interpretation and management

GFR 47 plus albuminuria A2 = CKD G3a A2 — high risk of progression on the KDIGO heat map. Management: optimize diabetes control (HbA1c < 7%, start an SGLT2 inhibitor — dapagliflozin or empagliflozin are indicated at GFR ≥ 25), control BP < 130/80 (ACE inhibitor/ARB at the maximum tolerated dose), statin, sodium restriction, caution with NSAIDs and contrast studies. Recheck GFR and albuminuria every 3-6 months. Refer to nephrology.

Limitations and cautions

In patients with extreme muscle mass (bodybuilders, amputees), accuracy is reduced — cystatin C or direct measurement should be used.
The equation does not apply to patients with rapidly changing creatinine (acute kidney injury, cachexia) — direct clearance measurement is needed.
Not suitable for dosing drugs with a narrow therapeutic window — these require specific equations (Cockcroft-Gault for aminoglycosides).
Pregnancy requires a separate algorithm accounting for physiologic changes.

Related calculators

Frequently asked questions

Why was race removed from the equation?

The race coefficient (1.16 for Black patients) overestimated GFR and delayed referral for transplantation. The 2021 version is more accurate without this coefficient and applies equally to all patients.

When should cystatin C be used?

For borderline results (GFR 45-60 with no other markers of kidney damage), in patients with extreme muscle mass, and to refine CKD staging in older adults.

At what GFR should a patient be referred to nephrology?

All patients with GFR < 30, rapid decline (> 5 mL/min/year), suspected glomerulonephritis, or significant albuminuria, per KDIGO guidance.

Cockcroft-Gault vs CKD-EPI — which to use?

CKD-EPI is used for CKD staging and general assessment. Cockcroft-Gault is used for dosing nephrotoxic drugs (retained for historical consistency in drug labeling).

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Aleksandr A. Aulov Physician, internal medicine, Sechenov School — independent medical education platform. Calculators are compiled from the original publications and current clinical guidelines. Interpretation thresholds follow the source study unless stated otherwise.

This calculator is intended for healthcare professionals. Do not use it for self-diagnosis or self-treatment. Management decisions are made by the treating clinician based on the full clinical picture of the individual patient.