Estimate creatinine clearance in mL/min with the Cockcroft-Gault equation from age, weight and creatinine, the traditional basis for drug dose adjustment.
years
kg
Enter the values to see the result here.
Calculation aids only. They do not replace clinical judgement or the drug reference. Verify every dose before using it on a patient.
Formula
With age in years, weight W in kilograms and serum creatinine Scr in mg/dL:
CrCl=72×Scr(140−age)×W(×0.85 for women)
The result is in mL/min. Creatinine in µmol/L is divided by 88.4 first.
Worked example
A 60-year-old man weighs 70 kg and has a creatinine of 1.0 mg/dL.
(140−60)×70=5600.
72×1.0=72.
5600/72=77.8 mL/min.
For a woman with the same values the answer is 77.8×0.85=66.1 mL/min.
Common mistakes
Entering creatinine in the wrong unit. A µmol/L value typed as mg/dL gives a tiny clearance.
Using total body weight in a very obese patient and overestimating clearance.
Applying it to unstable creatinine, for example in acute kidney injury, where any estimate is unreliable.
Treating the result as exact. Doses are normally adjusted in bands, not to the last mL/min.
Frequently asked questions
Why do drug labels still use Cockcroft-Gault?
Most dose-adjustment studies for renally cleared drugs were run with this equation, so the labels and guidelines were written around it. For a few newer drugs, regulators accept eGFR instead; read the individual label.
Which weight should I enter?
The equation was derived with actual weight in people near ideal body weight. In obesity, many hospital protocols use ideal or adjusted body weight, and in underweight patients the actual weight. Follow your local policy.
Does it work for children?
No. It was derived in adult men. Children are assessed with the bedside Schwartz equation instead.