Calculate creatinine clearance using the Cockcroft-Gault equation. Estimate kidney function for drug dosing and renal assessment.
The Creatinine Clearance Calculator estimates kidney function using the Cockcroft-Gault equation, the most widely used formula for drug dosing adjustments in patients with renal impairment. Unlike eGFR, creatinine clearance (CrCl) is measured in absolute mL/min (not normalized to body surface area), making it the preferred metric for pharmacokinetic applications.
The Cockcroft-Gault equation accounts for age, weight, sex, and serum creatinine. Since most drug labels specify dose adjustments based on CrCl rather than eGFR, this calculator remains indispensable in clinical pharmacy and medicine.
Enter your lab values and demographics to estimate your creatinine clearance and understand its implications for medication dosing and kidney health assessment. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process. This tool handles all the complex arithmetic so you can focus on interpreting results and making informed decisions based on accurate data.
Drug manufacturers base their dosing recommendations on creatinine clearance, not eGFR. When your doctor adjusts medication doses for kidney function, they almost always use the Cockcroft-Gault CrCl. This calculator helps you understand the number that directly affects your drug dosing. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Cockcroft-Gault Equation: CrCl (mL/min) = ((140 − age) × weight(kg)) ÷ (72 × Scr) • Multiply by 0.85 for females Where: • age = years • weight = actual body weight in kg • Scr = serum creatinine in mg/dL Note: For obese patients, adjusted body weight should be considered: ABW = IBW + 0.4 × (Actual − IBW) IBW(male) = 50 + 2.3 × (inches over 60) IBW(female) = 45.5 + 2.3 × (inches over 60)
Result: CrCl = 79.6 mL/min
CrCl = ((140 − 55) × 80) ÷ (72 × 1.2) = (85 × 80) ÷ 86.4 = 6800 ÷ 86.4 = 78.7 mL/min. This indicates mildly reduced kidney function. Many drugs don't require dose adjustment above 50 mL/min, but some sensitive medications may need adjustment below 80.
Donald Cockcroft and Henry Gault published their landmark equation in 1976 based on data from 249 male patients at Queen Mary Veterans Hospital in Montreal. The formula was remarkably simple yet effective, using readily available clinical data. Despite being nearly 50 years old, it remains the primary method for drug dosing adjustments because virtually all pharmacokinetic studies reference it.
The equation is less reliable in: extremes of body weight (very obese or cachectic), acute kidney injury (creatinine not at steady state), pregnancy, patients with limb amputations, and those on creatinine-altering medications (trimethoprim, cimetidine). In these cases, a timed urine collection for measured CrCl or cystatin C-based estimates may be preferable.
Pharmacists routinely calculate CrCl for renally-cleared medications. Common CrCl thresholds are <50, <30, and <15 mL/min, with dose reductions or contraindications at each level. Some protocols also specify maximum doses per CrCl range. Always consult current drug monographs for the latest recommendations.
Creatinine clearance (CrCl) is a measure of how quickly creatinine is removed from the blood by the kidneys. It estimates the rate at which the kidneys filter blood, expressed in mL per minute. It closely approximates the glomerular filtration rate and is the standard for drug dosing decisions.
CrCl is measured in absolute mL/min and depends on patient size. eGFR is normalized to a standard body surface area (1.73 m²). Drug dosing studies overwhelmingly used Cockcroft-Gault CrCl, so most drug labels reference CrCl. For clinical staging of CKD, eGFR (CKD-EPI) is preferred.
The 0.85 factor for females accounts for lower creatinine production due to generally lower muscle mass. Without this correction, CrCl would be overestimated in women because their baseline creatinine production is lower per kilogram of body weight.
The original Cockcroft-Gault study used actual body weight. For obese patients, using actual weight may overestimate CrCl. Many pharmacists use adjusted body weight (IBW + 0.4 × [Actual − IBW]) for patients more than 130% of IBW. For underweight patients, actual weight is appropriate.
Common medications with CrCl cutoffs include: metformin (hold if <30), enoxaparin (adjust <30), dabigatran (adjust <50), gabapentin/pregabalin (adjust <60), vancomycin (dose by CrCl), aminoglycosides, and many antibiotics. Always check individual drug labels.
No, the Cockcroft-Gault equation was developed for adults aged 18 and older. For pediatric patients, the Schwartz equation is used to estimate GFR. The original study population was adult males, with the female correction factor added later.