Estimate kidney function using the Cockcroft–Gault equation. Includes CKD staging, unit toggles, and clinical interpretation. Not a substitute for medical advice.
Female results multiplied by 0.85
Valid range: 1–120 years
Actual body weight (not ideal)
Normal: 0.7–1.3 mg/dL (61.9–114.9 μmol/L)
Male, 50yr, 70kg, SCr 1.0 → ≈87.5 mL/min
Female, 60yr, 60kg, SCr 1.1 → ≈53.4 mL/min
Male, 72yr, 80kg, SCr 2.5 → ≈26.1 mL/min (G4)
Female, 45yr, 55kg, SCr 0.8 → ≈85.5 mL/min
CrCl / eGFR (mL/min/1.73m²) direction: left to right
| Stage | CrCl / GFR Range | Description | Action |
|---|---|---|---|
| G1 | ≥ 90 mL/min | Normal or high | Annual monitoring if risk factors present |
| G2 | 60–89 mL/min | Mildly decreased | Monitor every 6–12 months |
| G3a | 45–59 mL/min | Mild–moderate decrease | Nephrology referral, review medications |
| G3b | 30–44 mL/min | Moderate–severe decrease | Active nephrology management |
| G4 | 15–29 mL/min | Severely decreased | Prepare for renal replacement therapy |
| G5 | < 15 mL/min | Kidney failure | Dialysis or transplant evaluation |
Creatinine clearance (CrCl) tells you how efficiently your kidneys are filtering creatinine — a waste product your muscles naturally produce — from your blood every minute. Think of it as a speedometer for kidney filtration: the higher the number, the better your kidneys are working. A healthy adult produces creatinine at a steady rate, so measuring how fast the kidneys remove it gives a reliable window into overall kidney performance.
The most widely used estimation method is the Cockcroft–Gault equation, developed in 1976 and still the gold standard for drug dosing calculations worldwide. Unlike eGFR (which is body-surface-area adjusted), Cockcroft–Gault gives a raw mL/min figure that pharmacists and physicians plug directly into dosing tables for antibiotics, anticoagulants, and chemotherapy agents.
The equation accounts for four variables that predict creatinine production and excretion:
The term captures the fact that muscle mass — and therefore creatinine production — naturally declines with age. Weight accounts for body mass (though ideal body weight is sometimes substituted in obese patients). The 0.85 female correction reflects that women typically have less muscle mass than men of the same weight, so they produce less creatinine at baseline.
Worked example: A 55-year-old male, 80 kg, SCr 1.2 mg/dL: — consistent with mild CKD G2.
Medical Disclaimer
This tool is for educational purposes only. It does not constitute medical advice. Creatinine clearance estimates have inherent limitations and should always be interpreted by a qualified healthcare professional in the context of the full clinical picture.