eGFR calculator (CKD-EPI 2021)

This calculator uses the race-free 2021 revision of the CKD-EPI creatinine equation, published by Inker et al. in the New England Journal of Medicine. It replaced the 2009 version, which included a race coefficient now recognised as clinically and scientifically unjustified. The equation combines serum creatinine with age- and sex-specific constants (κ and α) to produce an eGFR in mL/min/1.73m². This calculator accepts creatinine in either µmol/L or mg/dL and converts automatically.

Results are staged using the KDIGO 2012 chronic kidney disease classification: G1 (≥90, normal or high) and G2 (60–89, mildly reduced) are not diagnostic of CKD on their own without other markers of kidney damage. G3a (45–59) and G3b (30–44) split what used to be a single "moderate" stage for more precise clinical guidance. G4 (15–29) is severely reduced, and G5 (below 15) is kidney failure. An eGFR above 120 is capped and shown as ">120" rather than an unreliably precise figure.

eGFR is an estimate, not a direct measurement of kidney function, and creatinine-based equations can be less accurate at extremes of muscle mass, in acute kidney injury, during pregnancy, or in amputees. A single reading should generally be interpreted alongside trend data and, where relevant, a confirmatory test such as cystatin C. This tool is for reference only and is not a substitute for clinical judgement — interpretation and management decisions remain with the treating clinician.