Medication dosing estimate
Creatinine Clearance Calculator Using Cockcroft-Gault
Estimate creatinine clearance from age, weight, sex, and serum creatinine when a medicine's approved labeling specifically uses Cockcroft-Gault CrCl.
This estimate uses the original Cockcroft-Gault equation and actual body weight. Clinicians may select a different weight method for obesity or unusual body composition.
How this tool works
The original equation estimates CrCl in mL/min as (140 - age) × weight in kg ÷ (72 × serum creatinine in mg/dL), multiplied by 0.85 for the female term in the published formula. This calculator uses the entered actual body weight and converts µmol/L creatinine to mg/dL when needed.
CrCl and CKD-EPI eGFR are related but not interchangeable. CKD-EPI reports filtration normalized to 1.73 m² and is used for CKD evaluation and staging. Some medicine labels and pharmacokinetic studies still specify Cockcroft-Gault CrCl, so the method named by the label matters.
How to use it
- Confirm that the clinical question or medicine label calls for Cockcroft-Gault creatinine clearance.
- Enter age, weight, sex term, serum creatinine, and the creatinine unit exactly as measured.
- Review the result with a pharmacist or prescriber, especially if it is near a dosing threshold or body composition is unusual.
How to interpret the result
The output is an unindexed estimate in mL/min. A result should be compared with the exact renal-function ranges in the current approved medicine label; this site does not provide a dose recommendation.
Small differences can move a value across a label threshold. Clinicians may consider whether actual, ideal, or adjusted body weight is appropriate and whether kidney function is stable before acting on the estimate.
Limitations and safety
- The original equation was derived from hospitalized adult men and included a historical female coefficient; accuracy varies across populations and body composition.
- Actual body weight can overestimate CrCl in obesity, while creatinine can be misleading with low muscle mass, amputation, severe illness, pregnancy, or rapidly changing kidney function.
- Do not use this result alone to start, stop, or change a medicine. Follow the current product label and qualified clinical judgment.
Sources and method
Formula and interpretation checked against the following primary or authoritative sources. Editorial review date: September 9, 2026.