What is GFR?
The glomerular filtration rate (GFR) shows how well your kidneys filter waste from your blood. Doctors estimate it (eGFR) from a blood test for serum creatinine, plus your age and sex.
A falling eGFR can be an early sign of chronic kidney disease (CKD). This calculator uses the current race-free CKD-EPI 2021 equation and compares it with MDRD and Cockcroft-Gault.
How it is calculated
CKD-EPI 2021: 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 (if female)
κ = 0.7 (women) / 0.9 (men); α = −0.241 (women) / −0.302 (men)
Creatinine is in mg/dL; from µmol/L divide by 88.4. Results are in mL/min per 1.73 m² of body surface area.
Worked example
Woman, 60 years, creatinine 1.0 mg/dL
- CKD-EPI 2021 eGFR
- 64 mL/min/1.73 m²
- Stage
- G2 — Mildly decreased
Kidney function stages
| Stage | eGFR | Meaning |
|---|---|---|
| G1 | 90 or more | Normal or high |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mild to moderately decreased |
| G3b | 30–44 | Moderately to severely decreased |
| G4 | 15–29 | Severely decreased |
| G5 | 0–14 | Kidney failure |
eGFR is an estimate, not a diagnosis. CKD is diagnosed when reduced kidney function or urine abnormalities last more than 3 months. Discuss results with a doctor.