Creatinine Clearance Calculator (Cockcroft-Gault)

Estimate creatinine clearance (CrCl) in mL/min from age, sex, body weight and serum creatinine using the Cockcroft-Gault equation — the formula used in many drug labels for kidney-based dose adjustment.

years
Sex
Enter your values above — the result appears instantly. Nothing you type leaves your device.
Medical disclaimer: This calculator is intended for educational and informational purposes and does not replace professional medical advice, diagnosis, laboratory interpretation, or treatment. Laboratory methods and reference intervals vary. Always consult a qualified healthcare professional about your results.

How the Creatinine Clearance Calculator works

Creatinine clearance (CrCl) is an estimate of how quickly the kidneys remove creatinine from the blood. The Cockcroft-Gault equation, published in 1976, estimates CrCl from age, body weight, sex and a single serum creatinine value.

Unlike eGFR, the result is not normalized to body surface area — it is expressed in mL/min. Because many medicines were originally studied using Cockcroft-Gault, it is still referenced in drug labeling for renal dose adjustments.

Required inputs

  • Age (years, adults)
  • Sex
  • Body weight in kg or lb (converted to kg internally)
  • Serum creatinine in mg/dL or µmol/L

Formula used

CrCl (mL/min) = [(140 − age) × weight (kg)] ÷ [72 × serum creatinine (mg/dL)]
× 0.85 if female
  • Weight in lb × 0.4536 = kg
  • Creatinine in µmol/L ÷ 88.4 = mg/dL

This calculator uses the body weight you enter. Clinicians sometimes substitute ideal or adjusted body weight in people with obesity or low body weight — follow local protocols or the drug's labeling.

Worked example

A 60-year-old man weighing 70 kg with a serum creatinine of 1.0 mg/dL:

  • CrCl = [(140 − 60) × 70] ÷ (72 × 1.0) = 5,600 ÷ 72 ≈ 78 mL/min
  • For a woman with the same values: 77.8 × 0.85 ≈ 66 mL/min

Interpreting the result

There is no single "normal" CrCl cut-off for every purpose. Dose-adjustment thresholds are specific to each medicine and are set out in its prescribing information. A lower CrCl can suggest reduced kidney clearance, but results should be interpreted in clinical context together with eGFR, urine tests and trends over time.

Limitations

  • It is an estimate. Accuracy is reduced at extremes of body size (obesity, cachexia), in older adults with low muscle mass, in pregnancy, and in people with amputations or edema.
  • Not reliable when kidney function is changing rapidly (e.g. acute kidney injury).
  • The original equation was derived before creatinine assays were standardized (IDMS); modern assays give slightly lower creatinine values.
  • Medication dosing decisions require clinical judgment and the specific drug's labeling — do not change any medication based on this calculator.

Frequently asked questions

A 1976 formula that estimates creatinine clearance in mL/min from age, weight, sex and serum creatinine: [(140 − age) × weight] ÷ (72 × creatinine), multiplied by 0.85 for women.

CrCl (Cockcroft-Gault) is in mL/min and depends on body weight; eGFR (CKD-EPI) is normalized to 1.73m² body surface area and does not use weight. eGFR is preferred for staging kidney disease, while CrCl is often referenced for drug dosing.

The original equation used actual body weight. In people with obesity or very low weight, clinicians may use ideal or adjusted body weight instead. This calculator uses the weight you enter.

The formula assumes clearance falls with age because muscle mass and kidney function typically decline, which is why age is subtracted from 140.

No. Medication changes must be made by a qualified prescriber using the drug's labeling and the full clinical picture.
Medical disclaimer: This calculator is intended for educational and informational purposes and does not replace professional medical advice, diagnosis, laboratory interpretation, or treatment. Laboratory methods and reference intervals vary. Always consult a qualified healthcare professional about your results.