Creatinine Clearance Calculator (Cockcroft–Gault) | DrugChug

Creatinine clearance (CrCl) is a common way to estimate kidney function for renal dose adjustment, pharmacokinetics, and therapeutic drug monitoring education. This page provides a fast Cockcroft–Gault creatinine clearance calculator that uses age, weight, sex, and serum creatinine (SCr) to estimate CrCl in mL/min.

Use this calculator to learn how changes in serum creatinine, body weight, and age affect estimated renal function. If you’re studying antimicrobial dosing, vancomycin monitoring, or general clinical pharmacology, CrCl is one of the most frequently referenced estimates when thinking about drug clearance and dosing intervals.

Educational use only: CrCl is an estimate and may not reflect true kidney function in all patients. Always follow institutional protocols and clinician judgment.

Creatinine clearance approximates how effectively the kidneys clear creatinine from the blood. In drug dosing education, CrCl is commonly used as a practical estimate of renal elimination capacity—especially for medications that are primarily cleared by the kidneys.

CrCl is not the same as eGFR (estimated glomerular filtration rate). Many labs report eGFR automatically, but Cockcroft–Gault CrCl is still widely referenced in drug labeling and older dosing studies.

This calculator uses the classic Cockcroft–Gault approach:

• CrCl (mL/min) ≈ (140−age)×weight(kg)(140 − age) × weight (kg)(140−age)×weight(kg) ÷ 72×SCr(mg/dL)72 × SCr (mg/dL)72×SCr(mg/dL)
   
• For females, multiply the result by 0.85
   

• Age (years)
   
• Weight (kg or lb) — the calculator converts to kg automatically
   
• Sex (male/female)
   
• Serum creatinine (SCr) in mg/dL
   

• Estimated CrCl in mL/min, displayed immediately as you type

CrCl is often used to think through:

• Whether a drug’s dose should be reduced
• Whether the dosing interval should be extended (e.g., q12h → q24h)
• Whether serum concentrations might rise due to reduced clearance
   

In learning scenarios (like antibiotic PK), lower CrCl often implies lower drug clearance and potentially higher exposure at the same regimen—especially for primarily renally cleared drugs.

 No. CrCl (Cockcroft–Gault) and eGFR use different equations and assumptions. eGFR is often normalized to body surface area (mL/min/1.73m²), while CrCl is typically expressed as mL/min and often used for dosing references. 

 Different clinical protocols may use actual body weight, ideal body weight, or adjusted body weight in specific populations. This calculator is designed for education and uses the weight you enter (with unit conversion). For clinical use, follow your institution’s dosing policy. 

CrCl estimates can be less accurate in situations like:

• rapidly changing renal function (acute kidney injury)
• extremes of body size
• very low muscle mass or unusual creatinine generation
• unstable serum creatinine

• Weight: kg or lb
• SCr: mg/dL
• Output: mL/min