Creatinine Clearance Calculator

Creatinine clearance (CrCl) is an estimate of the kidneys' ability to filter creatinine — a waste product of normal muscle metabolism — from the blood. It serves as a proxy for the glomerular filtration rate (GFR) and is widely used to assess kidney function, detect chronic kidney disease, and guide drug dosing for medications cleared by the kidneys.

The Cockcroft-Gault equation estimates CrCl using age, body weight, sex, and serum creatinine: CrCl (mL/min) = [(140 − age) × weight (kg)] / [72 × serum creatinine (mg/dL)], multiplied by 0.85 for females. It was developed in 1976 and remains the most commonly used formula for drug dosing adjustments in clinical practice.

Normal CrCl is generally 90–120 mL/min for adults, though values naturally decline with age. Values between 60–89 mL/min suggest mildly reduced kidney function, 30–59 mL/min indicates moderate reduction, 15–29 mL/min is severely reduced, and below 15 mL/min is associated with kidney failure requiring dialysis or transplant.

Women typically have less muscle mass than men and therefore produce less creatinine. The Cockcroft-Gault formula accounts for this by multiplying the result by 0.85 for females, reducing the estimated CrCl to reflect the lower baseline muscle mass and creatinine generation rate.

For most patients, actual body weight (ABW) is used. However, in obese patients, some clinicians use ideal body weight (IBW) or an adjusted body weight to avoid overestimating kidney function. This calculator uses actual body weight as entered, which is the standard approach for the basic Cockcroft-Gault formula.

Creatinine clearance (CrCl) and glomerular filtration rate (GFR) both measure kidney filtration capacity, but they are calculated differently. CrCl from the Cockcroft-Gault equation tends to slightly overestimate true GFR because creatinine is also secreted by renal tubules. The CKD-EPI or MDRD equations are considered more accurate for staging chronic kidney disease, while Cockcroft-Gault is preferred for drug dosing.

Serum creatinine rises as kidney function declines — when the kidneys are unable to filter creatinine efficiently, it accumulates in the blood. However, creatinine levels alone can be misleading because they are also influenced by muscle mass, diet, and hydration status. That's why the Cockcroft-Gault equation incorporates age, sex, and weight alongside creatinine for a more meaningful estimate.

This calculator provides an educational estimate of CrCl based on the Cockcroft-Gault equation, which is commonly referenced in drug prescribing information. However, all clinical drug dosing decisions must be made by a qualified healthcare professional who can account for the patient's full medical context. Do not use this tool as a substitute for professional medical advice.