Creatinine Clearance Calculator

Creatinine clearance provides an estimate of a patient’s glomerular filtration rate (GFR) and is used to assess renal function. The Cockcroft-Gault equation was introduced in 1976. The equation is:

• CrCl = [(140 − age) × weight (kg)] / (72 × serum creatinine)
• Multiply by 0.85 for females

This formula accounts for age-related decline in kidney function and differences in muscle mass between sexes. While automated labs often report eGFR using MDRD or CKD-EPI formulas, the Cockcroft-Gault equation remains the standard in pharmacokinetics and dosing guidelines. Knowing how to determine creatinine clearance is critical when treating patients with fluctuating or impaired renal function.

This Cr clearance calculator is best used when dosing medications that are renally excreted, especially those with a narrow therapeutic index or potential for nephrotoxicity. Common use cases include dosing aminoglycosides, vancomycin, digoxin, and certain anticoagulants. It is also frequently used for evaluating renal function in patients with CKD, diabetes, heart failure, or those undergoing contrast imaging or major surgery.

The Cockcroft-Gault equation is favored in many dosing protocols because it uses actual body weight and allows for clinical flexibility. However, it does have limitations - particularly in patients with very low muscle mass, obesity, or rapidly changing creatinine levels. In such cases, clinicians may opt for adjusted body weight or consider alternative methods like MDRD or CKD-EPI. Despite these nuances, CrCl calculation remains one of the most accessible and clinically actionable ways to guide renal dosing.