Cockcroft Gault Creatinine Clearance
Calculator

It estimates creatinine clearance, a measure of how well your kidneys filter waste from the blood, using serum creatinine, age, weight, and sex. It's one of the older and most widely used formulas for approximating kidney function, particularly for medication dosing decisions.

Weight is used as a proxy for muscle mass, since creatinine is a byproduct of muscle metabolism and people with more muscle mass naturally produce and clear more creatinine. This is also why the formula can be less accurate in people with unusual body compositions, such as obesity or muscle wasting, where actual, ideal, or adjusted weight may be substituted.

Cockcroft-Gault estimates creatinine clearance and was developed before eGFR formulas like MDRD or CKD-EPI, which are now generally preferred for general kidney function assessment because they're more accurate across a wider range of patients. Cockcroft-Gault remains widely used specifically for drug dosing because many dosing guidelines were validated using it historically.

Because the formula assumes a typical relationship between weight and muscle mass, it can overestimate kidney function in frail, low-muscle patients and underestimate it in very muscular individuals. Clinicians often apply weight adjustments or use alternative formulas in these edge cases.

No, this is a clinical estimation tool meant to support, not replace, a healthcare provider's assessment of kidney function and dosing decisions. Any medication adjustment based on kidney function should be made by a qualified clinician.