Creatinine Clearance Calculator (Cockcroft-Gault)

The Cockcroft-Gault (CG) formula was developed in 1973 using data from 249 male patients with creatinine clearance ranging from approximately 30 to 130 mL/min. It estimates renal function using age, weight, sex, and serum creatinine. A correction factor of 0.85 is applied for female patients.

Normal CrCl is generally considered to be 90–130 mL/min, though it naturally declines with age. Values below 90 mL/min may indicate reduced kidney function. Stages are often classified as: ≥90 (normal), 60–89 (mild reduction), 30–59 (moderate reduction), 15–29 (severe reduction), and <15 mL/min (kidney failure).

Many drug dosing guidelines — particularly for renally cleared medications — were originally validated using the Cockcroft-Gault equation. Even though newer equations like CKD-EPI exist, CG remains the standard for pharmacokinetic drug dosing adjustments in clinical and pharmaceutical practice.

CG has not been re-expressed using standardized (IDMS-traceable) creatinine values, making it less accurate for estimating true GFR compared to the CKD-EPI or MDRD equations. It also is not adjusted for body surface area. For clinical GFR staging of CKD, CKD-EPI is preferred.

Yes. CG remains important for drug dosing, particularly in medications where dosing studies used this equation (e.g., direct oral anticoagulants, antibiotics, chemotherapy agents). It is also still widely used in research and to qualify patients for clinical trials based on renal function criteria.

This depends on the patient's body habitus. Total body weight (TBW) is used in normal-weight patients. In obese patients, ideal body weight (IBW) or adjusted body weight (AdjBW) is often preferred to avoid overestimating CrCl. This calculator uses the entered weight directly — clinicians should adjust for obesity as clinically appropriate.

Serum creatinine measured in µmol/L must be converted to mg/dL before applying the Cockcroft-Gault formula. The conversion factor is: mg/dL = µmol/L ÷ 88.4. This calculator handles that conversion automatically when you select µmol/L as your unit.

Women generally have lower muscle mass than men of the same weight and age, which results in less creatinine production. The 0.85 multiplier in the Cockcroft-Gault formula adjusts for this difference in muscle mass, yielding a more accurate CrCl estimate for female patients.