Creatinine Clearance (Cockcroft-Gault) Calculator
The Cockcroft-Gault equation estimates creatinine clearance (CrCl) in mL/min, a measure of kidney filtration function widely used for renal dose adjustments in clinical practice. Published in 1976, it remains the most commonly referenced equation in drug package inserts. Enter the patient's age in years, weight in kilograms, serum creatinine in mg/dL, and biological sex. The calculator applies the formula CrCl = ((140 - age) x weight x sex factor) / (72 x serum creatinine), where the sex factor is 1.00 for males and 0.85 for females. This tool is for educational and reference use only; clinical decisions require professional judgment and consideration of patient-specific factors.
Cockcroft-Gault formula
CrCl = ((140 - age) x weight x sex factor) / (72 x SCr)
Sex factor: Male = 1.00, Female = 0.85
Age is in years, weight in kg, serum creatinine (SCr) in mg/dL, and CrCl result is in mL/min. The female multiplier of 0.85 accounts for lower average muscle mass and creatinine production compared to males.
Interpreting creatinine clearance
- Above 90 mL/min: Normal or high kidney function.
- 60-89 mL/min: Mildly reduced. Corresponds roughly to CKD Stage 2 if kidney damage present.
- 30-59 mL/min: Moderately reduced (CKD Stage 3a/3b). Many drugs require dose reduction.
- 15-29 mL/min: Severely reduced (CKD Stage 4). Significant dose adjustments needed.
- Below 15 mL/min: Kidney failure (CKD Stage 5). Dialysis or transplant consideration.
Frequently asked questions
What is the Cockcroft-Gault equation?
The Cockcroft-Gault equation estimates creatinine clearance (CrCl) as a proxy for glomerular filtration rate. The formula is CrCl = ((140 - age) x weight x 0.85 if female) / (72 x serum creatinine). Weight is in kilograms, serum creatinine in mg/dL, and the result is in mL/min.
Why is the female multiplier 0.85?
Women generally have less muscle mass than men of the same weight, producing less creatinine per unit of kidney function. Multiplying by 0.85 corrects for this difference, giving a more accurate estimate of kidney function.
Which weight should I use: actual, ideal, or adjusted?
Current practice recommends using actual body weight for patients at or below ideal body weight. For obese patients, adjusted body weight (IBW + 0.4 x (actual - IBW)) is often preferred to avoid overestimating CrCl. Clinicians should apply institutional guidelines.
What CrCl value indicates chronic kidney disease stages?
Generally: CrCl above 90 mL/min is normal; 60-89 mildly reduced; 30-59 moderate; 15-29 severe; below 15 kidney failure. However, CKD staging uses eGFR from the CKD-EPI equation rather than Cockcroft-Gault in current guidelines.
How is Cockcroft-Gault used in drug dosing?
Many drug package inserts still reference Cockcroft-Gault CrCl for renal dose adjustments, particularly for renally cleared medications such as digoxin, vancomycin, and many antibiotics. Pharmacists use CrCl to determine appropriate doses and dosing intervals.
Official sources
- National Kidney Foundation: GFR Calculator and CKD Guidance.
- NIH National Institute of Diabetes and Digestive and Kidney Diseases: CKD Tests and Diagnosis.
- FDA Drug Labeling Resources: FDA Drugs.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.