This tool estimates adult creatinine clearance (CrCl) with the Cockcroft–Gault equation. The output is in mL/min. It is different from a lab-reported eGFR in mL/min/1.73 m² and from measured clearance using a timed urine sample.
Which equation and lab value does this use?
Estimated CrCl (mL/min) = (140 − age in completed years) × weight (kg) ÷ [72 × serum creatinine (mg/dL)]. Multiply by 0.85 for the equation’s female parameter. For a laboratory result in µmol/L, divide the creatinine value by 88.4 first. Enter serum creatinine, not urine creatinine.
The equation was published in 1976 and developed from 249 men aged 18–92. This tool uses the actual body weight entered and does not silently substitute ideal or adjusted body weight. The appropriate weight may differ by clinical situation.
Which value should I take from my report?
Enter serum creatinine with its reported unit, completed years of age and an actual measured weight in kilograms. Urine creatinine and an already-reported eGFR are different values. Software input limits, such as ages 18–120 and serum creatinine equivalent to 0.1–30 mg/dL, catch possible entry errors; they do not establish that the equation is clinically valid for every accepted input.
| Equation parameter | Estimated Cockcroft–Gault CrCl |
|---|---|
| Male parameter | (140−60)×70÷(72×1.20) ≈ 64.8 mL/min |
| Female parameter | Same initial calculation×0.85 ≈ 55.1 mL/min |
A serum creatinine of 1.20 mg/dL is 106.08 µmol/L. These two parameter choices illustrate the equation; they do not instruct someone to choose a parameter or medication dose without an individual clinical review. This estimate is neither a GFR category nor a 24-hour measured urine clearance.
How should I interpret the number?
The number is estimated CrCl. Contemporary 2021 CKD-EPI eGFR uses a different equation and reporting unit. A CrCl of 44 mL/min must not be assigned the same GFR category as an eGFR of 44 mL/min/1.73 m². This page does not assign a CKD stage or suggest a medicine dose.
A CKD assessment considers whether kidney abnormalities persist for at least three months, urine albumin, eGFR, and the underlying cause. The right kidney measure for a medication depends on its label and the clinical situation; do not start, stop, or alter a medicine from this result. The U.S. National Kidney Foundation advocates transitioning medication-related decisions from Cockcroft–Gault toward current race-free eGFR equations.
When might the estimate be misleading?
Very small or large body size, obesity, fluid retention, amputation, substantially different muscle mass, older age, and differences in creatinine assays can affect interpretation. In overweight or obesity, a clinician may consider ideal or adjusted body weight, but no single automatic weight choice works for everyone. Some medicine labels specify actual body weight, so the label and individual clinical judgment matter. Do not automatically round a low creatinine result in an older person up to 1.0 mg/dL.
Rapidly changing creatinine during acute kidney injury or serious illness does not meet the stable-function assumption behind this estimate. Pregnancy and dialysis require a different assessment of kidney function and medicine removal. The original development data covered ages 18–92; results above that range deserve additional caution. Ask your laboratory or clinician if the equation’s sex parameter does not clearly fit your circumstances.
Frequently asked questions
Why does this differ from eGFR on my lab report?
Cockcroft–Gault estimates CrCl using age, body weight, and serum creatinine. The 2021 CKD-EPI equation estimates GFR differently and usually reports a value indexed to 1.73 m² of body surface area. The values cannot be substituted for one another.
Can I choose a medication dose from my CrCl?
No. Some older medication labels still refer to CrCl, but the required measure and interpretation vary by medicine and person. Discuss your own medication and new lab result with your prescriber or pharmacist.
Reviewing this with other results
- Record the date, serum creatinine unit, and when and how your current weight was measured. Compare prior laboratory results.
- The eGFR calculator and urine ACR calculator use different specimens and provide different information.
- The eGFR versus CrCl guide can help you ask your prescriber or pharmacist which measure and units apply to a particular medicine.
Related calculators and sources
Health calculators · 2021 CKD-EPI eGFR calculator · Adult BMI calculator. Contact your clinical team promptly about a result that has changed markedly or concerning symptoms.
Original Cockcroft–Gault paper (1976) · NKF: Limitations of Cockcroft–Gault · FDA: Renal pharmacokinetics guidance (2024) · NIDDK: Creatinine unit conversion · KDIGO 2024 CKD guideline · UK Kidney Association pregnancy guidance. Sources and examples checked by Life Choice Note, 26 September 2026. No independent physician review has been performed. This is general information, not individual medical or dosing advice. Editorial standards · Disclaimer