Kidney function · Dosing reference
Cockcroft-Gault creatinine clearance.
Enter age, weight, serum creatinine and sex to get the Cockcroft-Gault estimate of creatinine clearance in mL/min, the equation many drug labels still cite for dose adjustment.
A 70-year-old woman weighing 70 kg with a serum creatinine of 1.2 mg/dL has a Cockcroft-Gault creatinine clearance of 48.2 mL/min. A 50-year-old man at 80 kg with a creatinine of 1.0 mg/dL comes to 100.0 mL/min.
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How the Cockcroft-Gault equation works
Creatinine clearance (mL/min) = (140 - age) × weight (kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 for women. It was published by Cockcroft and Gault in Nephron in 1976. The shape is easy to read: (140 - age) lowers the estimate for every year of age, weight stands in for muscle mass and therefore creatinine production, and the creatinine in the denominator lowers the estimate as blood creatinine rises. The 0.85 reflects lower average creatinine production in women. The equation is written this way, with age in years, weight in kg and creatinine in mg/dL, in the CJASN comparison paper listed under Sources.
If you enter creatinine in umol/L the tool divides by 88.4 to get mg/dL, and pounds are divided by 2.20462 to get kilograms. Nothing is rounded until the final display. The result is in plain mL/min, not indexed to body surface area, which is the main practical difference from the CKD-EPI eGFR. Drug labels written before eGFR reporting became standard often give dose rules in Cockcroft-Gault mL/min, which is why the older equation is still in daily use.
Worked example
Woman, 70, 70 kg, creatinine 1.2 mg/dL. (140 - 70) = 70, times 70 kg = 4,900. The denominator is 72 × 1.2 = 86.4. 4,900 / 86.4 = 56.7, and times 0.85 gives 48.2 mL/min. For a man aged 50 at 80 kg with a creatinine of 1.0: (140 - 50) × 80 = 7,200, divided by 72 × 1.0 = 100.0 mL/min, with no female factor.
Weight is where people go wrong. Michels and colleagues compared Cockcroft-Gault with the CKD-EPI and MDRD equations in 271 patients and found its accuracy fell as body weight and BMI rose: 57.1% in the heaviest group, against 87.0% for CKD-EPI. Their conclusion was that Cockcroft-Gault remains a good alternative in older people and in those with low body weight or BMI. The paper does not say which weight (actual, ideal or adjusted) it used, so this page does not either: it multiplies by the weight you type in.
Common mix-ups
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Often assumedCockcroft-Gault, MDRD and CKD-EPI are interchangeable, so any of them gives about the same answer.
What the source saysIn a 271-patient comparison, Cockcroft-Gault accuracy fell to 57.1% in the heaviest group, against 87.0% for CKD-EPI, while it stayed a good alternative in older and low-weight patients. The gap depends on body size. [1]
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Often assumedThe weight in Cockcroft-Gault is just "your weight", so there is nothing to decide.
What the source saysThe CJASN comparison reports body weight in kg but does not state whether actual, ideal or adjusted weight was used. Which one to enter in overweight patients is a clinical choice that references handle differently. [1]
Checked against these sources on .
Frequently asked questions
What is the Cockcroft-Gault formula?
Creatinine clearance in mL/min = (140 - age in years) x weight in kg / (72 x serum creatinine in mg/dL), multiplied by 0.85 for women. It comes from a 1976 paper by Cockcroft and Gault in Nephron.
Which body weight should I enter?
The equation as published uses body weight in kg. Whether to use actual, ideal or adjusted body weight in overweight patients is a clinical decision that differs between references, so this calculator uses the number you enter and does not choose for you.
How is this different from eGFR?
Cockcroft-Gault gives creatinine clearance in mL/min from weight and age. CKD-EPI 2021 gives eGFR indexed to 1.73 m2 of body surface area and does not use weight. They can disagree, especially at the extremes of body size.
How accurate is Cockcroft-Gault at high body weight?
In one 271-patient comparison its accuracy was 57.1% in the heaviest group, against 97.0% for MDRD and 87.0% for CKD-EPI in the same group, while it held up in older and lighter patients.
Can I use this to dose a drug myself?
No. Dose rules depend on the specific drug label, the weight convention it uses and your clinical picture. Use this as a reference calculation and have a pharmacist or prescriber confirm any dose.
Sources
CheckedSources retrieved
- Michels WM et al: Performance of the Cockcroft-Gault, MDRD, and new CKD-EPI formulas in relation to GFR, age, and body size (Clin J Am Soc Nephrol, 2010)
- National Kidney Foundation: CKD-EPI Creatinine Equation (2021)
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Not medical advice
This calculator does arithmetic on the numbers you type and does not diagnose or treat anything. Results depend on the quality of the inputs and the equation used. Lab values, drug doses and ECG readings must be interpreted by a clinician who knows the patient; contact your care team or emergency services for anything urgent.