The eGFR calculator estimates glomerular filtration rate using the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation and classifies kidney function into CKD stages according to KDIGO 2022 guidelines. eGFR is the standard measure of kidney function reported alongside routine serum creatinine results by most laboratories. It is used to diagnose, monitor, and stage chronic kidney disease, and to guide medication dose adjustments and nephrology referral decisions.
| Stage | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high |
| 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 |
eGFR (from MDRD or CKD-EPI) is reported by laboratories and is standardised to a body surface area of 1.73 m². CrCl (from Cockcroft-Gault) is used for drug dosing and is not BSA-normalised. For most clinical purposes, CrCl is preferred for drug dose adjustment decisions.
An eGFR below 15 mL/min/1.73m² is classified as CKD Stage G5 — kidney failure. At this stage, dialysis or kidney transplant is considered. An eGFR below 30 (Stage G4) warrants nephrology referral and preparation for renal replacement therapy.