Creatinine Clearance Calculator

CrCl is an estimate of how well your kidneys filter waste from your blood, expressed in milliliters per minute (mL/min). It's calculated from your age, sex, weight, and serum creatinine level using the Cockcroft-Gault formula. It's used to stage kidney disease and adjust medication doses for drugs cleared by the kidneys.

CrCl = [(140 − age) × weight in kg × (0.85 if female)] / (72 × serum creatinine in mg/dL). This formula, developed in 1976, estimates creatinine clearance and remains the standard for medication dosing decisions in clinical practice.

For healthy adults, normal CrCl is roughly 90-120 mL/min for men and 80-110 mL/min for women. CrCl naturally declines with age — by about 1 mL/min per year after age 40. A CrCl of 70 mL/min in a 75-year-old may be normal for that age, while it would be concerning in a 30-year-old.

Both estimate kidney function. CrCl (Cockcroft-Gault) reports raw mL/min and is preferred for medication dosing. eGFR (CKD-EPI 2021) reports mL/min per 1.73 m² (normalized for body size) and is preferred for CKD diagnosis and staging. They give similar but not identical results for the same patient.

Women typically have less muscle mass than men of the same age and weight, so they produce less creatinine. The Cockcroft-Gault formula multiplies the result by 0.85 for females to account for this. Without this adjustment, women's kidney function would be underestimated.

For most patients: actual body weight. For obese patients (>30% above ideal), using actual body weight may overestimate CrCl — many clinicians use adjusted body weight or ideal body weight in obese patients. For underweight or muscle-wasted patients, actual body weight may underestimate kidney function.

CrCl naturally declines with age, even in healthy people. From peak values around age 30, CrCl decreases by about 1 mL/min per year. By age 80, a normal CrCl might be 60-80 mL/min. This is why the formula uses (140 − age) as a starting point — it builds in the expected age-related decline.

Many drugs require renal dose adjustments, including: most antibiotics (especially aminoglycosides, vancomycin), digoxin, lithium, metformin, gabapentin, allopurinol, many cancer drugs, low-molecular-weight heparins, and direct oral anticoagulants (DOACs). Always check the drug label or institutional protocols for specific dosing.

Yes, particularly in early diabetes (hyperfiltration) or pregnancy (normal physiological increase). A very high CrCl (>140 mL/min) in a non-pregnant person may indicate early diabetic kidney disease and warrants further evaluation.

The Cockcroft-Gault formula is reasonably accurate (±20-30%) for most adults with stable kidney function. Accuracy decreases in extreme body weights, pregnancy, acute kidney injury, and significant muscle wasting. This calculator is for educational and planning purposes — clinical decisions should be made by qualified healthcare providers using the full clinical picture.