What Is the Cockcroft-Gault Creatinine Clearance Calculator?
This calculator estimates creatinine clearance (CrCl) — a measure of how well your kidneys filter waste — using the classic Cockcroft-Gault equation. CrCl is widely used by clinicians to gauge renal function and to adjust the dose of drugs that are cleared by the kidneys. The result is expressed in milliliters per minute (mL/min). This tool is for educational support only and does not replace clinical judgment or laboratory-measured clearance.
How to Use It
Select the patient's sex, then enter age in years, body weight in kilograms, and the serum creatinine value in mg/dL (the common US lab unit). Press calculate to see the estimated CrCl and a general kidney-function category. For females, the equation automatically applies a 0.85 correction factor reflecting lower muscle mass.
The Formula Explained
The Cockcroft-Gault equation is:
$$\text{CrCl} = \frac{\left(140 - \text{Age}\right)\times \text{Weight (kg)}}{72 \times \text{SCr (mg/dL)}}$$, multiplied by \(0.85\) if the patient is female.
Age reduces clearance (older kidneys filter less), weight increases the numerator (more muscle generates more creatinine), and a higher serum creatinine — meaning waste is building up — lowers the calculated clearance.
Worked Example
Consider a 60-year-old male weighing 70 kg with a serum creatinine of 1.0 mg/dL. $$\text{CrCl} = \frac{\left(140 - 60\right) \times 70}{72 \times 1.0} = \frac{80 \times 70}{72} = \frac{5600}{72} \approx 77.78 \text{ mL/min}$$ indicating mildly reduced clearance.
FAQ
Should I use actual or ideal body weight? Cockcroft-Gault was originally derived with total body weight, but clinicians often use ideal or adjusted body weight in obese patients. This tool uses the weight you enter.
Why multiply by 0.85 for females? Women generally have less muscle mass, producing less creatinine, so the equation scales the estimate down.
Is CrCl the same as GFR? Not exactly. CrCl estimates glomerular filtration but tends to slightly overestimate true GFR because some creatinine is also secreted by the tubules.
