Creatinine Clearance Calculator
Estimate creatinine clearance using the Cockcroft–Gault equation with age, sex, weight, height, and serum creatinine.
Results
This calculator is for educational estimation only and is not medical advice. Cockcroft–Gault creatinine clearance is not the same as lab-reported eGFR, is not body-surface-area adjusted, and may be unreliable when serum creatinine is not stable. Always confirm medication dosing or kidney function decisions with a qualified clinician.
The Creatinine Clearance Calculator estimates CrCl using the Cockcroft-Gault equation from age, sex, body weight and serum creatinine. It is commonly encountered in medication references, but the number is an estimate and is not interchangeable with every laboratory eGFR result.
Clinical warning: Do not diagnose kidney disease or change a medicine dose from this page alone. Confirm the equation, weight convention, laboratory units, current prescribing information and patient-specific factors with a clinician or pharmacist.
Inputs that control the Cockcroft-Gault result
Age is entered in years, weight in kilograms, and serum creatinine usually in mg/dL. If the laboratory reports micromoles per liter, convert the value correctly before calculating. A unit error can change the estimate by an order of magnitude.
The traditional equation estimates clearance in mL/min. Some clinical decisions instead use kidney-function values normalized to body surface area, reported as mL/min/1.73 m². Those numbers answer related but different questions.
The equation and its sex factor
For the traditional male equation: CrCl = (140 − age) × weight ÷ (72 × serum creatinine). The historical female adjustment multiplies that result by 0.85. The calculator applies the selected input path consistently and shows an estimate rather than a measured clearance.
These coefficients came from an older population and creatinine-assay era. Modern patients can differ in body composition, health status and laboratory calibration, which is one reason professional interpretation remains necessary.
Which body weight belongs in the formula?
Actual, ideal or adjusted body weight may be used in different protocols, particularly when body size is far from the range in which the equation performs best. There is no universally correct replacement rule for every drug and patient. Follow the policy or prescribing source relevant to the decision.
Document the weight value and method used. Two calculators can disagree simply because one used actual weight and the other used an adjusted value.
Creatinine can make the estimate misleading
Serum creatinine reflects both renal handling and creatinine production. Low muscle mass, amputation, frailty, unusual muscularity, rapidly changing kidney function, pregnancy and some medicines can reduce the reliability of a steady-state equation.
When kidney function is changing quickly, a single creatinine measurement may lag behind the clinical situation. Measured clearance, repeat testing or an alternative biomarker may be more informative when a decision is high stakes.
Example without turning it into a dose recommendation
For a 60-year-old man weighing 80 kg with serum creatinine of 1.0 mg/dL, the traditional arithmetic is (140−60)×80÷72, which is about 88.9 mL/min. That worked example only demonstrates the formula. It does not identify a diagnosis or a safe dose for any medication.
Checks before using a CrCl estimate
- Confirm mg/dL versus µmol/L
- Verify current age and an appropriate recent weight
- Identify which weight convention the relevant protocol requires
- Check whether kidney function is stable
- Use the exact renal metric specified in current drug labeling
Related calculations and records
Use the Dose Calculator only for arithmetic based on an already verified instruction. The Body Surface Area Calculator can explain normalization concepts, but it should not be used to convert values for clinical decisions without a validated method.
Creatinine Clearance Calculator FAQ
Is CrCl the same as eGFR?
No. They use different equations and may be reported with different normalization. Use the measure required for the specific clinical purpose.
Can I use a creatinine result from months ago?
Only a qualified professional can judge whether it still represents current kidney function. Acute illness and medication changes can make an old value unsuitable.
Why do calculators return different answers?
Differences often come from units, rounding, sex factors or the chosen body weight rather than the core equation itself.
The FDA has published the traditional Cockcroft-Gault creatinine-clearance equation in renal-function guidance.
