Kidney function education
Creatinine Clearance Calculator: Cockcroft–Gault
Estimate adult creatinine clearance using age, actual body weight, sex and serum creatinine when a medicine label specifies Cockcroft–Gault.
Actual weight can overestimate clearance in obesity. Low muscle mass, amputation, pregnancy, severe illness or rapidly changing kidney function can reduce reliability. A value near a dosing threshold needs clinical review.
Method and equation
The original equation estimates CrCl in mL/min. A is age in years, W is actual weight in kg, and SCr is serum creatinine in mg/dL; f is 0.85 for the published female term and 1 for the male term. Creatinine in µmol/L is divided by 88.4. The equation originated in hospitalized adult men, with a historical female correction. It estimates creatinine clearance rather than directly measuring glomerular filtration.
CrCl = (140 − A) × W / (72 × SCr) × f
How to use this tool
- Check that the medicine's current approved label calls for this method. Enter the measured values and the exact creatinine unit. This version uses actual body weight; a pharmacist or prescriber may choose ideal or adjusted weight in specific circumstances.
- Review the original report, earlier results and relevant urine tests with a qualified clinician before making a care decision.
Worked example
For a 65-year-old man weighing 70 kg with creatinine 1.2 mg/dL, (140 − 65) × 70 ÷ (72 × 1.2) gives about 60.8 mL/min. The female coefficient gives about 51.6 mL/min for otherwise identical inputs.
Understanding the result
CrCl is unindexed mL/min; CKD-EPI eGFR is usually indexed to 1.73 m². They are not interchangeable. Compare the result only with the renal-function method and ranges stated in the current medicine label; this tool does not recommend a dose.
Limitations and safety
- Actual weight can overestimate clearance in obesity. Low muscle mass, amputation, pregnancy, severe illness or rapidly changing kidney function can reduce reliability. A value near a dosing threshold needs clinical review.
- Educational use only. A result cannot diagnose disease or choose a medicine dose. Do not delay urgent care for symptoms or rapidly changing kidney results.
Sources
Method and explanations checked against the sources below on October 14, 2026. This is editorial and technical verification, not a physician review. External sources may be in English.