estimated creatinine clearance calculator

What this estimated creatinine clearance calculator does

This calculator estimates creatinine clearance (CrCl) using the Cockcroft-Gault equation. In clinical practice, CrCl is often used to adjust doses for drugs cleared by the kidneys. It is not exactly the same as eGFR, though the two are related.

This tool is for education and quick estimation only. Always confirm with a licensed clinician, pharmacist, and local dosing guidelines.

Inputs explained

1) Age

Kidney filtration generally declines with age, so age is built directly into the equation.

2) Sex at birth

The Cockcroft-Gault equation applies a multiplier (0.85) for females to account for average differences in muscle mass and creatinine generation.

3) Body weight

Weight selection can significantly change results. For some patients, using actual body weight may overestimate kidney function. This is why IBW/AdjBW options are included.

• Actual body weight: uses entered weight directly.
• Ideal body weight (IBW): estimated from sex and height.
• Adjusted body weight (AdjBW): often used when actual weight is well above IBW.
• Auto: uses adjusted weight if actual weight is more than 120% of IBW.

4) Serum creatinine

Serum creatinine is accepted in either mg/dL or µmol/L (automatically converted). Values should reflect a relatively stable kidney state; rapidly changing kidney function may make this estimate unreliable.

How to use this calculator

• Enter age, sex at birth, body weight, and serum creatinine.
• Select your preferred unit options.
• Choose the weight method (Auto is a practical default).
• Click Calculate Creatinine Clearance.
• Review the estimated CrCl and interpretation band.

Result interpretation bands (general)

• ≥ 90 mL/min: normal or near-normal range
• 60–89 mL/min: mildly reduced range
• 30–59 mL/min: moderately reduced range
• 15–29 mL/min: severely reduced range
• < 15 mL/min: kidney failure range

These categories are broad and not a diagnosis by themselves. Clinical context, trend over time, and laboratory methods all matter.

Clinical limitations to keep in mind

• Less reliable in acute kidney injury (rapidly changing creatinine).
• Can be inaccurate at extremes of body size, age, or muscle mass.
• Pregnancy, limb amputation, severe malnutrition, and cirrhosis may affect accuracy.
• Drug dosing recommendations may specify a particular weight method or alternate equation.

Quick example

For a 65-year-old female, 70 kg, serum creatinine 1.1 mg/dL, using actual body weight: CrCl ≈ ((140−65)×70)/(72×1.1)×0.85 ≈ 56 mL/min. That falls in a moderately reduced range and may affect dosing for renally cleared medications.

Bottom line

This estimated creatinine clearance calculator gives a fast Cockcroft-Gault estimate with practical weight options. It is useful for learning and screening, but medication and diagnosis decisions should always be made with professional clinical judgment.