Creatinine Clearance Calculator (Cockcroft-Gault)
Estimate creatinine clearance with the Cockcroft-Gault equation from age, weight, serum creatinine and sex (US units, mg/dL).
How to use this tool
- Enter age in years and body weight in kilograms.
- Enter serum creatinine in mg/dL.
- Select sex to apply the 0.85 factor for females.
- Read the estimated creatinine clearance and category.
The Cockcroft-Gault creatinine clearance calculator estimates kidney filtration from age, weight, serum creatinine and sex — the equation long used for renal drug dosing.
Formula
CrCl (mL/min) = ((140 − age) × weight) ÷ (72 × serum creatinine)
Multiply the result by 0.85 for females. Age is in years, weight in kilograms, and serum creatinine in mg/dL.
How it works
The Cockcroft-Gault equation estimates creatinine clearance, a proxy for kidney filtration, from age, body weight, serum creatinine and sex. Clearance falls with age and with rising creatinine, and women receive a 0.85 multiplier to reflect lower average muscle mass. It remains widely used for renal drug dosing because many dosing studies were built on it.
This calculator uses US conventional units (creatinine in mg/dL). The estimate assumes stable kidney function; it is unreliable when creatinine is changing rapidly, and the choice of body weight (actual, ideal, or adjusted) strongly affects the result in people who are very lean or who carry excess weight. eGFR equations such as CKD-EPI are now preferred for staging kidney disease.
This calculator is provided for general information and education only and is not medical advice. Clinical formulas are screening and estimation tools, not diagnoses, and they assume valid, correctly-measured inputs. Always consult a qualified clinician before making any decision about your health.
Worked example
60-year-old man, 80 kg, creatinine 1.0 mg/dL
- 140 − age = 140 − 60 = 80
- Multiply by weight: 80 × 80 = 6400
- Denominator: 72 × 1.0 = 72
- Divide: 6400 ÷ 72 = 88.8889 mL/min
- Male, so no 0.85 factor; round = 88.89 mL/min
Creatinine Clearance = 88.89 mL/min (Mildly reduced)
CrCl for an 80 kg man at age 60 across creatinine levels
| Serum creatinine (mg/dL) | CrCl (mL/min) |
|---|---|
| 0.8 | 111.11 |
| 1.0 | 88.89 |
| 1.5 | 59.26 |
| 2.0 | 44.44 |
| 3.0 | 29.63 |
Key terms
- Creatinine clearance (CrCl)
- An estimate of how much blood the kidneys clear of creatinine per minute, used as a marker of kidney filtration.
- Serum creatinine
- A waste product of muscle metabolism filtered by the kidneys; higher levels generally indicate lower filtration.
- Cockcroft-Gault equation
- The 1976 formula that estimates creatinine clearance from age, weight, creatinine and sex.
- eGFR
- Estimated glomerular filtration rate, a related kidney-function measure now preferred for staging chronic kidney disease.
Frequently asked questions
- What is a normal creatinine clearance?
- A CrCl of roughly 90 mL/min or above is generally considered normal for adults, though it declines naturally with age. Lower values suggest reduced kidney filtration.
- Which weight should I enter?
- Cockcroft-Gault was derived with actual body weight, but clinicians often use ideal or adjusted weight for very lean or heavier patients to avoid over- or underestimating clearance.
- Is creatinine clearance the same as eGFR?
- They are related but not identical. Cockcroft-Gault CrCl is still used for drug dosing, while eGFR equations like CKD-EPI are preferred for staging chronic kidney disease.