Creatinine Clearance Calculator
Estimate your creatinine clearance (CrCl) using the Cockcroft-Gault equation. Enter age, body weight, sex, and serum creatinine to see your kidney function estimate and CKD stage.
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.
Frequently Asked Questions
What is a normal creatinine clearance?
Normal creatinine clearance in healthy young adults is roughly 90-140 mL/min. Values decline by about 1 mL/min per year after age 40, so an otherwise healthy 70-year-old may sit in the 60-80 range without having kidney disease.
What is the difference between CrCl and eGFR?
Creatinine clearance from Cockcroft-Gault uses age, weight, sex, and serum creatinine. eGFR from CKD-EPI uses age, sex, race, and creatinine without weight. CKD-EPI is more accurate for CKD staging, but Cockcroft-Gault CrCl is still what most drug labels reference for dose adjustment.
When is Cockcroft-Gault unreliable?
It is unreliable in obesity (use adjusted body weight), very low muscle mass, rapidly changing kidney function, pregnancy, children, and amputees. In those cases clinicians use 24-hour urine collection or different estimating equations.
Why do some medications need dose reduction?
Many drugs are cleared by the kidneys. When clearance drops, unchanged drug and active metabolites accumulate, raising the risk of toxicity. Common examples include metformin (stop below CrCl 30), apixaban (reduce below 50), and gabapentin (reduce below 60).
Is this tool medical advice?
No. This calculator is for education and convenience only. Any decisions about CKD diagnosis, staging, or medication dosing require a clinician who can interpret the result in the context of your full medical history and lab trends.