Creatinine Clearance Calculator (Cockcroft-Gault)

Calculate estimated creatinine clearance using the Cockcroft-Gault equation, a measure of kidney function commonly used historically for medication dosing reference. Educational tool only.

💊 Clinical Reference📐 CrCl = [(140-Age) × Weight] / (72 × SCr)🏥 Health
Sex
Age (years)
Weight (kg)
Serum creatinine (mg/dL)
Please enter valid values.

Formula & Reference

VariableSymbolFormulaUnits
Creatinine Clearance Calculator (Cockcroft-Gault)—CrCl = [(140-Age) × Weight] / (72 × SCr)mL/min

Step-by-Step Examples

Example 1
Normal Function

Male, age 40, weight 80kg, SCr=0.9.

  • CrCl = [(140-40)×80]/(72×0.9) = 8000/64.8 = 123.5
  • Above normal threshold — excellent kidney function
✓ CrCl ≈ 124 mL/min (normal)
Example 2
Mildly Decreased

Female, age 65, weight 65kg, SCr=1.1.

  • Base = [(140-65)×65]/(72×1.1) = 4875/79.2 = 61.6
  • Female adjustment: 61.6×0.85 = 52.4
  • Falls in moderately decreased range
✓ CrCl ≈ 52 mL/min (moderately decreased)
Example 3
Significantly Reduced

Male, age 78, weight 70kg, SCr=2.0.

  • CrCl = [(140-78)×70]/(72×2.0) = 4340/144 = 30.1
  • Borderline moderate-to-severe reduction, common in elderly population
✓ CrCl ≈ 30 mL/min (moderately-severely decreased)

Real-World Applications

💊
Medication Dosing Reference
Historically widely used for renal dose adjustment of many medications, especially in older clinical guidelines and drug references.
👨‍⚕️
Nephrology Practice
Kidney function trending using creatinine clearance helps monitor chronic kidney disease progression.
📚
Pharmacy Education
Cockcroft-Gault calculation remains a standard teaching topic despite newer eGFR equations becoming more common.
🏥
Clinical Trial Eligibility
Many drug studies historically used Cockcroft-Gault CrCl thresholds for inclusion/exclusion criteria.

Common Mistakes to Avoid

⚠️
Using actual body weight in obese or edematous patients without adjustment

Cockcroft-Gault can overestimate kidney function in obese patients; some clinicians use adjusted or ideal body weight in these situations — consult current clinical guidelines.

⚠️
Confusing Cockcroft-Gault CrCl with newer eGFR equations

CKD-EPI and MDRD equations are now often preferred over Cockcroft-Gault in many clinical contexts, though Cockcroft-Gault remains specifically referenced in some drug dosing guidelines.

⚠️
Using this for actual medication dosing decisions

This is an educational reference tool only — actual medication dosing requires consultation of current prescribing information and clinical judgment by qualified healthcare providers.

Frequently Asked Questions

What is creatinine clearance used for? ▾
Historically used as an estimate of kidney filtration function (GFR), particularly important for adjusting doses of renally-cleared medications to avoid toxicity in reduced kidney function.
What is the difference between CrCl and eGFR? ▾
Cockcroft-Gault CrCl uses age, weight, sex, and creatinine. Modern eGFR equations (CKD-EPI) use age, sex, race (in some versions), and creatinine but not weight, and are now often preferred for general kidney function assessment.
Why does Cockcroft-Gault include weight but eGFR formulas typically don't? ▾
Cockcroft-Gault estimates total creatinine clearance (which scales with body size), while eGFR equations are normalized to standard body surface area (1.73m²), removing the need for weight in the calculation.
Is Cockcroft-Gault still used clinically? ▾
Yes, particularly for medication dosing where original drug trials and FDA labeling were based on Cockcroft-Gault calculations, making it still relevant for certain dosing decisions despite newer GFR equations existing.
What factors can affect creatinine clearance accuracy? ▾
Muscle mass (creatinine is a muscle breakdown product), extremes of body weight, rapidly changing kidney function, and certain medications can all affect the accuracy of calculated estimates.

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