Creatinine Clearance Calculator
Cockcroft-Gault, the standard for renal drug dosing.
Ideal or adjusted body weight is usually preferred over actual weight in obesity.
Which weight you enter materially changes the result and is the most common source of error. Follow local pharmacy guidance for the drug being dosed.
Creatinine clearance (Cockcroft-Gault)
78 mL/min
Mildly reduced
Cockcroft-Gault is not normalised to body surface area, so it is not interchangeable with eGFR. Use eGFR for staging, this for dosing.
How the Creatinine Clearance Calculator works
Cockcroft-Gault estimates creatinine clearance from serum creatinine, age, weight and sex. It is older and less accurate than modern eGFR equations for staging kidney disease, but it remains the formula most drug labels were written against — so it is still the one used for dose adjustment.
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
What is the Cockcroft-Gault equation?
CrCl = ((140 − age) × weight in kg) ÷ (72 × serum creatinine in mg/dL), multiplied by 0.85 for women. It was published in 1976 from a sample of 249 patients, almost all male.
Which weight should I use in Cockcroft-Gault?
This is the most common source of error. Actual body weight overestimates clearance in obesity; most references recommend ideal body weight, or adjusted body weight when the patient is more than about 30% above ideal. Follow local pharmacy guidance.
Cockcroft-Gault or eGFR?
Use eGFR (CKD-EPI) to stage chronic kidney disease, and Cockcroft-Gault for drug dosing unless the label specifies otherwise. They are not interchangeable: eGFR is normalised to body surface area and Cockcroft-Gault is not, so they can differ substantially in people at either extreme of size.
What limits its accuracy?
Serum creatinine depends on muscle mass, so it overestimates function in frail or elderly patients with low muscle and underestimates it in muscular ones. It is also unreliable when kidney function is changing rapidly, since creatinine lags behind.