Creatinine Clearance Calculator

Creatinine Clearance Calculator for Nephrology. The output is an estimated clearance in mL/min mapped to conventional function bands: roughly ≥90 normal, 60–89 mildly reduced, 30–59 moderately reduced, 15–29 severely reduced, and <15 kidney failure. In drug dosing the actionable thresholds are the specific cutoffs printed in each label rather than these general bands: common breakpoints include <50 mL/min (dabigatran, many antibiotics), <30 mL/min (rivaroxaban, dabigatran contraindication territory, nitrofurantoin caution), 25 mL/min (apixaban), and <15 mL/min (avoid most DOACs). Cross the relevant threshold and the drug is reduced, spaced, or withheld.

How this calculator works

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) in mL/min from serum creatinine, age, weight, and sex: CrCl = [(140 − age) × weight (kg)] / [72 × serum creatinine (mg/dL)], multiplied by 0.85 for females. It approximates 24-hour urinary creatinine clearance by predicting daily creatinine generation (which falls with age and rises with muscle mass/weight) and dividing by the measured serum concentration. Unlike CKD-EPI or MDRD, it yields a non-indexed clearance in absolute mL/min rather than mL/min/1.73 m², which is why it remains embedded in most FDA drug-labeling dose thresholds.

When to use this calculator

Use Cockcroft-Gault primarily for renal drug dosing, since the majority of approved package inserts and dose-adjustment tables (e.g., DOACs such as apixaban, rivaroxaban, and dabigatran; aminoglycosides; vancomycin nomograms; many chemotherapeutics) were validated against CrCl in mL/min. It is appropriate for adults with stable kidney function. Do not use it in acute kidney injury or any rapidly changing creatinine, in children (use Schwartz/bedside CKiD instead), or as the preferred estimate for CKD staging and eGFR reporting, where KDIGO now endorses the 2021 race-free CKD-EPI creatinine equation.

Inputs used

  • Age
  • Weight
  • Sex
  • Serum creatinine

Clinical interpretation

The output is an estimated clearance in mL/min mapped to conventional function bands: roughly ≥90 normal, 60–89 mildly reduced, 30–59 moderately reduced, 15–29 severely reduced, and <15 kidney failure. In drug dosing the actionable thresholds are the specific cutoffs printed in each label rather than these general bands: common breakpoints include <50 mL/min (dabigatran, many antibiotics), <30 mL/min (rivaroxaban, dabigatran contraindication territory, nitrofurantoin caution), 25 mL/min (apixaban), and <15 mL/min (avoid most DOACs). Cross the relevant threshold and the drug is reduced, spaced, or withheld.

Worked example

A 72-year-old woman, 60 kg, serum creatinine 1.1 mg/dL: CrCl = [(140 − 72) × 60] / [72 × 1.1] × 0.85 = (68 × 60) / 79.2 × 0.85 = 4080 / 79.2 × 0.85 = 51.5 × 0.85 ≈ 44 mL/min. For apixaban in atrial fibrillation this sits above the 25 mL/min dose-reduction floor but, combined with age ≥80 or weight ≤60 kg, would trigger the 2.5 mg twice-daily reduction; here the 60 kg weight satisfies one reduction criterion.

Limitations and safety notes

Because it uses total body weight, Cockcroft-Gault substantially overestimates CrCl in obesity (consider adjusted or ideal body weight) and can underestimate in cachexia or amputees with low muscle mass. It is unreliable in AKI, pregnancy, extremes of age, and severe liver disease with low creatinine generation. It was derived in a predominantly male 1970s cohort using non-IDMS-standardized creatinine assays, so modern IDMS-traceable creatinine values can shift the estimate; it has not been recalibrated to current assays the way CKD-EPI has.

Frequently asked questions

Which weight should I enter in an obese patient?

Total body weight inflates the estimate because the numerator scales with weight while muscle-derived creatinine does not rise proportionally with fat mass. Many clinicians use ideal body weight, or adjusted body weight when actual exceeds ideal by more than about 20-30%, to avoid overdosing renally cleared drugs.

Should I use Cockcroft-Gault or CKD-EPI?

Use CKD-EPI 2021 for CKD staging and eGFR reporting per KDIGO, since it is more accurate and standardized to modern creatinine assays. Use Cockcroft-Gault for drug dosing when the drug label's thresholds were established against creatinine clearance in mL/min, which is still the case for most approved products including the DOACs.

Why is there a 0.85 factor for females?

Women on average have lower muscle mass and therefore lower daily creatinine generation for a given weight, so the equation multiplies by 0.85 to correct the predicted creatinine production downward.

Can I use it in acute kidney injury?

No. The equation assumes steady-state serum creatinine. During AKI the creatinine lags behind true GFR, so a still-low creatinine will make clearance look falsely preserved while function is actually dropping.

Does it need body surface area correction?

No. Cockcroft-Gault deliberately reports non-indexed clearance in mL/min. Do not apply the 1.73 m2 normalization used for eGFR, because drug labels expect the absolute value.

References

  • Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41. PMID: 1244564.
  • Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737-1749. PMID: 34554658.
  • Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2024.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: March 14, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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