Creatinine Clearance Calculator

What Is Creatinine Clearance?

Creatinine clearance is an estimate of how fast the kidneys filter creatinine out of the blood, expressed in mL/min. It is a standard proxy for glomerular filtration rate (GFR) and is used to stage chronic kidney disease and adjust drug dosing. Normal young-adult values sit around 90-140 mL/min and decline roughly 1 mL/min per year after age 40.

The Cockcroft-Gault Formula

Cockcroft-Gault is: CrCl = ((140 − age) × weight in kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 if female. It was derived in 1973 and remains the formula most drug labels use for renal dose adjustment, even though CKD-EPI is now preferred for CKD staging. It performs best for adults with stable kidney function and a typical body composition.

Interpreting the Result

CrCl above 90 mL/min is generally normal. 60-89 is mild reduction, 30-59 is moderate CKD, 15-29 is severe CKD, and under 15 is kidney failure. Many medications — including metformin, apixaban, and gabapentin — require dose reduction or avoidance below specific CrCl thresholds, which is why clinicians calculate this before prescribing.

Important Safety Note

This tool is informational only and is not medical advice. Cockcroft-Gault becomes unreliable in obesity, very low muscle mass, pregnancy, rapidly changing kidney function, and in children. Use adjusted body weight for obesity and always confirm dosing decisions with a clinician or pharmacist.