What this calculator does
The Cockcroft-Gault equation estimates creatinine clearance (CrCl) in mL/min. Clinicians often use this estimate to guide medication dosing, especially for drugs that are eliminated through the kidneys. This tool is designed for quick educational use and gives an immediate estimate based on age, sex, weight, and serum creatinine.
The Cockcroft-Gault equation
The classic formula is:
CrCl = ((140 − age) × weight in kg) / (72 × serum creatinine in mg/dL)
For females, multiply the result by 0.85.
Variables used
- Age: Older age lowers the estimate.
- Weight: Higher weight increases the estimate (in this standard form).
- Serum creatinine: Higher creatinine lowers the estimate.
- Sex factor: Female estimates are multiplied by 0.85.
How to use this cockroft and gault calculator
- Enter age in years.
- Select sex at birth (required by the original equation).
- Enter body weight in kilograms.
- Enter serum creatinine and choose its unit (mg/dL or µmol/L).
- Click Calculate CrCl.
Interpreting your result
Creatinine clearance categories are often used for practical renal dosing discussions. These ranges are broad and do not replace professional judgment:
| Estimated CrCl (mL/min) | General Interpretation |
|---|---|
| ≥ 90 | Near normal kidney filtration range |
| 60–89 | Mild reduction |
| 30–59 | Moderate reduction |
| 15–29 | Severe reduction |
| < 15 | Kidney failure range (urgent clinical review) |
Important clinical caveats
1) Not for unstable kidney function
Cockcroft-Gault assumes relatively stable serum creatinine. In acute kidney injury, the estimate may be unreliable.
2) Weight selection matters
In obesity, edema, or very low body mass, which weight to use (actual, ideal, or adjusted) can significantly change the result. This calculator uses the exact weight you enter, so use clinical judgment.
3) Different equations serve different purposes
eGFR equations (such as CKD-EPI) are often used for chronic kidney disease staging, while many drug labels still reference Cockcroft-Gault for dosing.
Quick example
If a 65-year-old male weighs 70 kg and has serum creatinine 1.1 mg/dL:
CrCl = ((140 - 65) × 70) / (72 × 1.1) = 66.3 mL/min (approx).
Bottom line
This cockroft and gault calculator is useful for rapid renal dosing estimates, but it should be treated as a decision-support tool, not a diagnosis. Always interpret results alongside full clinical context, medication profile, and professional guidance.