Creatinine Clearance
Cockcroft-Gault Equation
Result
Estimated Creatinine Clearance (CrCl)
Classification:
Stage (approximate):
Note: For CrCl ≥ 60 mL/min, the Cockcroft-Gault equation may overestimate renal function. CKD staging in this range is more accurate with CKD-EPI or MDRD. Confirm with an alternative equation if the clinical context requires it.
CrCl by CG is not normalized to 1.73 m² — KDIGO staging is approximate
Renal Function Classification
Based on KDIGO stages. CrCl by CG is not normalized to 1.73 m²; staging is approximate.
| CrCl (mL/min) | Classification | Stage |
|---|---|---|
| ≥ 90 | Normal or elevated | G1 |
| 60 – 89 | Mildly decreased | G2 |
| 45 – 59 | Mildly to moderately decreased | G3a |
| 30 – 44 | Moderately to severely decreased | G3b |
| 15 – 29 | Severely decreased | G4 |
| < 15 | Kidney failure | G5 |
About the Cockcroft-Gault Equation
Equation
CrCl (mL/min) = [(140 − age) × weight] / (72 × serum creatinine)
For female patients: multiply the result by 0.85
Clinical Application
The primary use of the Cockcroft-Gault equation is drug dose adjustment for medicines with predominantly renal excretion (antibiotics, anticoagulants, antidiabetics, and others). Many FDA-approved Prescribing Information (PI) documents and pharmacological guidelines base their dose adjustment criteria on this equation. Cockcroft-Gault remains the reference equation embedded in most FDA-approved drug labels for dosing in renal impairment, as the pivotal trials establishing dosing thresholds were conducted using CG-derived CrCl rather than eGFR — even though the National Kidney Foundation (NKF) now recommends race-free eGFR equations for CKD staging and, increasingly, for other clinical decisions. For CKD staging, MDRD or CKD-EPI is preferred.
Which weight to use — a critical consideration
The original equation was derived in a population with limited numbers of obese patients. In obese patients, using actual body weight overestimates CrCl. Recommended practice:
- • Actual body weight (ABW): when there is no significant obesity
- • Ideal body weight (IBW): Males = 50 + 0.91 × (height in cm − 152.4); Females = 45.5 + 0.91 × (height in cm − 152.4)
- • Adjusted body weight (AdjBW): IBW + 0.4 × (ABW − IBW) — recommended when ABW > 120% of IBW
Limitations
May overestimate CrCl in elderly patients, obese individuals, and those with low muscle mass (cachexia, amputations). Not suitable for patients on dialysis, with acutely changing renal function, or at extremes of muscle mass. Not normalized to body surface area (1.73 m²).
Note: This calculator provides an estimate of CrCl. The result must be interpreted in the clinical context of the patient, including hydration status, muscle mass, and stability of renal function. In obese patients, enter ideal or adjusted body weight to avoid overestimation. This tool does not replace individualized clinical assessment.
References
- 1. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41. PubMed ↗
- 2. Winter MA, Guhr KN, Berg GM. Impact of various body weights and serum creatinine concentrations on the bias and accuracy of the Cockcroft-Gault equation. Pharmacotherapy. 2012;32(7):604–612. PubMed ↗