Free tool
Creatinine Clearance.
The Cockcroft-Gault estimate of creatinine clearance — the number drug references actually use to adjust renal dosing (eGFR is for staging, not dosing). The part that trips people up is which weight to use. This tool computes the clearance from actual, ideal, and adjusted body weight, recommends the one to use, and shows the safety caveats. Runs on your device — no PHI leaves the page.
Cockcroft-Gault creatinine clearance
Enter age, sex, serum creatinine, and weight. Add a height to unlock the ideal / adjusted weight logic.
Enter age, sex, creatinine, and weight.
Which weight does Cockcroft-Gault use?
There's no single right answer, but the common clinical-pharmacy convention is:
| Situation | Use |
|---|---|
| Actual weight is below ideal (underweight) | Actual body weight |
| Actual weight is near ideal (within ~20%) | Ideal body weight (IBW) |
| Actual weight is > 1.2 × ideal (obese) | Adjusted body weight |
IBW (Devine) needs a sex and a height ≥ 5 ft. Adjusted body weight = IBW + 0.4 × (actual − IBW). The result above shows the clearance for each weight and flags the recommended one — but always follow the weight your pharmacy or drug reference specifies for the specific medication.
Reading the clearance
| CrCl (mL/min) | Renal function | For dosing |
|---|---|---|
| ≥ 90 | Normal / high | Usually full dose unless drug says otherwise. |
| 60–89 | Mildly decreased | Most drugs full dose; check the label. |
| 30–59 | Moderately decreased | Many drugs need adjustment; common cut-points at <50 and <30. |
| 15–29 | Severely decreased | Significant dose reduction or avoidance for many renally-cleared drugs. |
| < 15 | Kidney failure | Specialist / pharmacy input; many drugs contraindicated or dialysis-dosed. |
These bands mirror the GFR categories used to describe kidney function, but Cockcroft-Gault gives creatinine clearance in mL/min (not normalized to 1.73 m²) — that raw mL/min value is what most drug labels and FDA renal-dosing tables were built around, so keep it un-normalized for dosing.
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41.
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655. (Ideal body weight formula.)
- U.S. FDA. Guidance for Industry: Pharmacokinetics in Patients with Impaired Renal Function — Study Design, Data Analysis, and Impact on Dosing. (Cockcroft-Gault CrCl as the basis for renal dose labeling.)
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD. Kidney Int. 2024;105(4S):S117–S314. (GFR categories; eGFR for staging vs CrCl for drug dosing.)
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