Creatinine Clearance Calculator (Cockcroft-Gault)
Estimate creatinine clearance with the Cockcroft-Gault equation from age, weight, sex and serum creatinine — widely used for drug dosing.
How it works
CrCl = ((140 − age) × weight in kg) ÷ (72 × serum creatinine) × 0.85 if female
Cockcroft-Gault, published in 1976, estimates how fast the kidneys clear creatinine and remains the reference many medication labels use when they call for a dose adjustment in renal impairment. It rises with body weight, falls with age and serum creatinine, and multiplies by 0.85 for women to reflect lower average muscle mass. Note that it gives an absolute clearance in mL/min — not indexed to body surface area like eGFR — so the two numbers are related but not interchangeable, and it can overestimate clearance in people carrying a lot of extra body weight.
Worked example
A 50-year-old man weighing 70 kg with a serum creatinine of 1.0 mg/dL: CrCl = ((140 − 50) × 70) ÷ (72 × 1.0) = 6,300 ÷ 72 = 87.5 mL/min.
Frequently asked questions
How is this different from eGFR?
Cockcroft-Gault estimates creatinine clearance in raw mL/min using actual body weight, while the CKD-EPI eGFR is normalised to a 1.73 m² body surface. Drug dosing guidance is usually written against Cockcroft-Gault, so it is still calculated even though eGFR is used to stage kidney disease.
Which weight should I use?
The original equation uses actual body weight, which is what this calculator does. In people who are significantly overweight, clinicians often substitute ideal or adjusted body weight to avoid overestimating clearance for medication dosing.
Why the 0.85 factor for women?
Creatinine is produced by muscle, and women on average carry less muscle mass, so they generate less creatinine at the same kidney function. The 0.85 multiplier corrects for that difference.
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Educational estimate, not medical advice — for clinical decisions consult a healthcare professional.