eGFR Calculator (CKD-EPI 2021)
Estimate glomerular filtration rate using the 2021 CKD-EPI creatinine equation (race-free). Output is in mL/min/1.73 m².
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Disclaimer: For educational purposes only. Not a substitute for clinical judgment.
About This Tool
What Is eGFR?
Estimated glomerular filtration rate (eGFR) is the best overall index of kidney function in health and disease. The 2021 CKD-EPI creatinine equation — endorsed by KDIGO, NKF, and ASN — is a race-free formula that uses serum creatinine, age, and sex to estimate GFR in mL/min/1.73 m². This replaced the 2009 CKD-EPI equation that included a race coefficient, addressing concerns about health equity and biological rationale.
When to Use eGFR
eGFR should be calculated and reported automatically whenever serum creatinine is measured. It is essential for CKD screening and staging (KDIGO G1–G5), determining eligibility for contrast-enhanced imaging, guiding referral to nephrology (typically eGFR <30 or rapidly declining), and monitoring disease progression. However, eGFR should not be used in acute kidney injury (AKI), where creatinine is not at steady state.
Interpreting eGFR Results
CKD is defined as eGFR <60 mL/min/1.73 m² or markers of kidney damage (albuminuria, hematuria, structural abnormalities) persisting for ≥3 months. A single low eGFR does not establish CKD — chronicity must be confirmed. The KDIGO heat map combines G-stage (eGFR) with A-stage (albuminuria) to categorize risk of progression and guide management intensity.
🔑 Clinical Pearls
- eGFR is normalized to 1.73 m² BSA. For drug dosing, many labels reference CrCl (Cockcroft-Gault), which is not BSA-adjusted — use the appropriate equation per the drug label.
- Creatinine-based eGFR can be inaccurate in extremes of muscle mass (amputees, bodybuilders, malnourished patients). Consider cystatin C-based or combined equations.
- eGFR >90 with no markers of damage is G1 (normal), but persistently elevated creatinine with eGFR 60–89 and no damage markers is G2 (mildly decreased), which alone does not constitute CKD.
- A drop of >5 mL/min/1.73 m²/year suggests rapid progression warranting nephrology referral.
Key References
- Inker LA, et al. New Creatinine- and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–1749.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD. Kidney Int. 2024.
- Delgado C, et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force. Am J Kidney Dis. 2022;79(2):268–288.
Formula last verified: February 2026