Cockcroft-Gault Formula — Creatinine Clearance Calculator
Calculate creatinine clearance using the Cockcroft-Gault formula with weight, age, sex, and serum creatinine. Free calculator.
Cockcroft-Gault Creatinine Clearance Formula
The Cockcroft-Gault formula is the most widely used equation for estimating creatinine clearance (CrCl) and kidney function in adults. It was published in 1976 and remains the standard for drug dosing adjustments.
The Formula
CrCl (mL/min) = [(140 − Age) × Weight (kg) × Sex factor] / [72 × Serum Creatinine (mg/dL)]
Sex factor: 1.0 for males, 0.85 for females.
Reference Values
| CrCl (mL/min) | CKD Stage | Interpretation |
|---|---|---|
| >90 | Normal / G1 | Normal kidney function |
| 60–89 | G2 – Mild decrease | Mildly reduced |
| 30–59 | G3 – Moderate | Moderately reduced |
| 15–29 | G4 – Severe | Severely reduced |
| <15 | G5 – Kidney failure | Kidney failure |
When to Use Cockcroft-Gault
Pharmaceutical guidelines for drug dosing (e.g., renal dose adjustments for antibiotics, anticoagulants, and diabetes medications) primarily reference Cockcroft-Gault CrCl rather than GFR. Always use actual body weight unless the patient is obese, in which case ideal body weight (IBW) is recommended.
Frequently Asked Questions
Why does the Cockcroft-Gault formula use a correction factor of 0.85 for females?
Women have a lower muscle mass relative to body weight compared to men, resulting in less creatinine production per kilogram. The 0.85 factor accounts for this difference, producing a more accurate estimate of renal clearance for female patients.
Should I use actual body weight or ideal body weight in the Cockcroft-Gault formula?
Use actual body weight (ABW) for patients of normal weight. For obese patients (ABW more than 30% above IBW), use ideal body weight or adjusted body weight to avoid overestimating creatinine clearance.