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CrCl vs eGFR Calculator — Which to Use for Drug Dosing
Creatinine clearance (CrCl) and eGFR are not interchangeable, and using the wrong one is a common error. CrCl from the Cockcroft-Gault equation is the traditional standard for renal drug dosing — most pharmacokinetic studies and FDA/EMA labels use it, and it is not indexed to body surface area. eGFR (CKD-EPI 2021) is used to stage and diagnose chronic kidney disease and is BSA-indexed (mL/min/1.73m²). A simple rule: use CrCl for drug dosing, and eGFR for CKD classification. This calculator estimates CrCl with Cockcroft-Gault (CrCl = [(140 − age) × kg × (0.85 ♀)] ÷ (72 × Scr mg/dL)) and shows the general renal-dosing tier it lands in; for CKD staging use the eGFR calculator instead. Because they use different equations and units, the two numbers can differ for the same patient — so do not read an eGFR as a dosing clearance or vice versa. This is an estimate for dose adjustment, not dosing advice, and a clinician decision. Free, private, browser-only.
CrCl (Cockcroft-Gault) → renal drug dosing, not BSA-indexed
- eGFR (CKD-EPI 2021) → CKD staging, BSA-indexed (mL/min/1.73m²)
- When in doubt: CrCl for dosing, eGFR for classification
Frequently asked questions
What is the difference between CrCl and eGFR?
CrCl (Cockcroft-Gault) is the standard for renal drug dosing — most drug labels use it, and it is not BSA-indexed. eGFR (CKD-EPI 2021) is for staging chronic kidney disease and is BSA-indexed (mL/min/1.73m²). They use different equations, so the two numbers can differ for the same patient. Use CrCl for dosing and eGFR for classification.
Which should I use for drug dosing — CrCl or eGFR?
Use CrCl from Cockcroft-Gault for renal drug dosing, because that is what most pharmacokinetic studies and FDA/EMA labels are based on. eGFR is for CKD staging. Some newer guidance references eGFR for certain drugs, but the drug label is the authority — check it. It is an estimate for dose adjustment, not dosing advice.