Creatinine Clearance Calculator (Cockcroft-Gault)
Estimate creatinine clearance (CrCl) using age, sex, weight, and serum creatinine. This is commonly used to support kidney function assessment and medication dosing decisions.
The term CR clearance usually refers to creatinine clearance, an estimate of how effectively your kidneys remove creatinine from your blood. This calculator uses the Cockcroft-Gault equation, which remains widely used in clinical settings—especially for medication dose adjustment.
What is creatinine clearance?
Creatinine is a waste product generated by muscle metabolism. Healthy kidneys filter it out of the bloodstream and eliminate it through urine. Creatinine clearance (CrCl) estimates filtration efficiency and is reported in mL/min.
Because direct urine-based clearance testing can be cumbersome, clinicians often estimate CrCl from routine blood tests plus patient characteristics.
Formula used in this calculator
This page uses the Cockcroft-Gault equation:
CrCl (male) = ((140 − age) × weight in kg) / (72 × serum creatinine in mg/dL)
CrCl (female) = CrCl (male) × 0.85
If you enter serum creatinine in µmol/L, the tool converts it first:
Serum creatinine (mg/dL) = serum creatinine (µmol/L) ÷ 88.4
How to use the CR clearance calculator
- Enter age in years.
- Select biological sex (used by the standard equation factor).
- Enter body weight in kilograms.
- Input serum creatinine and choose the correct unit.
- Optionally enter height to get a BSA-normalized estimate (mL/min/1.73m²).
- Click Calculate CrCl.
How to interpret the result
The output includes your estimated CrCl and a broad kidney function category:
- 90 mL/min or higher: Normal or near normal range.
- 60–89 mL/min: Mildly reduced.
- 30–59 mL/min: Moderately reduced.
- 15–29 mL/min: Severely reduced.
- Below 15 mL/min: Kidney failure range.
These categories are general guidance and should always be interpreted with symptoms, trend over time, urinalysis, and clinician judgment.
Why CrCl still matters
Medication dosing
Many drugs are cleared by the kidneys. CrCl is often used to decide if a dose should be reduced, spaced out, or avoided altogether.
Clinical decision support
CrCl can complement eGFR in practical treatment decisions, especially in pharmacy and inpatient workflows.
Important limitations
- It is an estimate, not a direct measured clearance.
- Accuracy may be lower in extremes of body composition, rapidly changing kidney function, pregnancy, or critical illness.
- A single value is less useful than a trend over time.
- Different institutions may use adjusted body weight rules in obesity for dosing purposes.
Frequently asked questions
Is CrCl the same as eGFR?
No. They are related estimates but calculated differently and used for slightly different purposes. eGFR is often used for CKD staging, while CrCl is commonly used for drug dosing.
Should I use actual body weight or ideal body weight?
This calculator uses the weight you enter directly. In practice, some protocols use ideal or adjusted body weight for specific patients and medications. Follow your local clinical guideline.
Can I use this as a diagnosis tool?
No. This tool is educational and informational. Only a licensed clinician can diagnose or treat kidney disease.
Medical disclaimer: This calculator does not replace professional medical advice, diagnosis, or treatment. If your result is concerning, speak with a qualified healthcare professional.