Creatinine Clearance Calculator (Cockcroft-Gault) Formula

Understand the math behind the creatinine clearance calculator (cockcroft-gault). Each variable explained with a worked example.

Use the Creatinine Clearance Calculator (Cockcroft-Gault)

Formulas Used

Creatinine Clearance

crcl = ((140 - age) * weight_kg) / (72 * serum_creatinine) * gender_factor

GFR Estimate

kidney_stage = ((140 - age) * weight_kg) / (72 * serum_creatinine) * gender_factor

Variables

VariableDescriptionDefault
ageAge(years)50
weight_kgWeight(kg)80
serum_creatinineSerum Creatinine(mg/dL)1
gender_factorGender1

How It Works

Cockcroft-Gault Equation

CrCl = [(140 - Age) x Weight(kg)] / [72 x Serum Creatinine] x (0.85 if female)

This equation estimates creatinine clearance as a proxy for glomerular filtration rate (GFR).

Kidney Function Stages

CrCl (mL/min)Stage >90Normal 60-89Mild decrease 30-59Moderate decrease 15-29Severe decrease <15Kidney failure

Worked Example

A 50-year-old male, 80 kg, serum creatinine 1.0 mg/dL.

age = 50weight_kg = 80serum_creatinine = 1gender_factor = 1
  1. 01CrCl = (140 - 50) x 80 / (72 x 1.0)
  2. 02= 90 x 80 / 72
  3. 03= 7200 / 72 = 100 mL/min (Normal)

Frequently Asked Questions

What is creatinine clearance?

Creatinine clearance measures how well the kidneys filter creatinine from the blood. It serves as an estimate of the glomerular filtration rate (GFR).

Why is this equation important?

The Cockcroft-Gault equation is widely used for adjusting drug dosages in patients with reduced kidney function. Many drug labels reference this equation.

What is a normal creatinine level?

Normal serum creatinine is typically 0.7-1.3 mg/dL for men and 0.6-1.1 mg/dL for women. Higher values may indicate reduced kidney function.

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Open Creatinine Clearance Calculator (Cockcroft-Gault)