Creatinine Clearance (CrCl)
The definitive calculator for renal drug dosing. Estimate kidney function using the Cockcroft-Gault equation to ensure safe medication administration.
Cockcroft-Gault
Standard formula
Drug Dosing
Adjustment guide
Weight Factor
Uses ABW/IBW
Gender Specific
0.85 Correction
What is Creatinine Clearance?
CrCl estimates the rate at which your kidneys clear creatinine from the blood. It is used primarily to determine the correct dosage for medications that are excreted by the kidneys.
CrCl vs. eGFR
While eGFR (CKD-EPI) is better for staging kidney disease, CrCl (Cockcroft-Gault) remains the standard for FDA-approved drug labeling. This means when a drug label says "Reduce dose if renal function is < 30 mL/min," it is referring to CrCl, not eGFR.
Weight Dependent
Unlike eGFR, the Cockcroft-Gault formula includes body weight, making it sensitive to muscle mass and obesity.
FDA Standard
Most older drug studies used this formula, so it remains the benchmark for dosing antibiotics and anticoagulants.
Age Factor
Kidney function naturally declines with age. This formula adjusts heavily for age, preventing overdose in the elderly.
Dosing Safety
Calculate precise renal function to avoid toxicity in drugs like Vancomycin or Gentamicin.
IBW Adjustment
For obese patients, we automatically calculate Ideal Body Weight (IBW) to prevent overestimation of clearance.
Unit Flexible
Works with mg/dL (US) and µmol/L (International) creatinine units.
Why Use Our Calculator?
Clinical Precision
We implement the specific logic for obesity adjustment (using Adjusted Body Weight if BMI > 30), which simple calculators miss.
Instant Staging
We color-code the result (Normal, Mild, Moderate, Severe) to give immediate context to the number.
Secure
Calculations run locally. Patient data never leaves the device, ensuring HIPAA compliance for professionals.
How to Use the CrCl Calculator
Get the right number for dosing.
Enter Serum Creatinine
Input the value from the patient's blood work. Ensure you select the correct unit (mg/dL or µmol/L).
Input Patient Demographics
Enter age, gender, weight, and height. Height is required to calculate Ideal Body Weight (IBW), which is crucial for accurate dosing in overweight patients.
Evaluate Results
The result will show the estimated Creatinine Clearance in mL/min. Use this number to adjust medication dosages according to the package insert.
Understanding the Variables
Why do we need all this info to check your kidneys?
Serum Creatinine
A waste product from muscle breakdown. Healthy kidneys filter it out. High levels in blood = low kidney function.
Age & Gender
Kidney function declines naturally with age. Women generally have less muscle mass than men, producing less creatinine, so the formula adjusts (x 0.85) for females.
Weight & Height
The formula assumes creatinine comes from muscle. In obesity, total weight includes excess fat (no creatinine). We use Height to find "Ideal Weight" to correct this error.
Calculate CrCl
Based on Cockcroft-Gault Formula.
Understanding CrCl Levels
How this number guides clinical decisions.
Normal (> 90 mL/min)
Kidneys are clearing waste effectively. Standard doses of medication are typically safe.
Moderate (30 - 59 mL/min)
"Renal Impairment." Many drugs require a dose reduction (e.g., taking a pill every 24 hours instead of every 12) to prevent accumulation.
Severe (< 30 mL/min)
Significant loss of function. Some drugs are contraindicated (unsafe to use) at this level. Close monitoring is essential.
The Math Behind the Tool
The Cockcroft-Gault Equation (1976).
The Formula
CrCl = [ (140 - age) × Weight(kg) ] / ( 72 × SCr )
*Multiply by 0.85 for females.
Why Weight Matters?
This formula assumes creatinine production is proportional to muscle mass. However, in obesity, total weight overestimates muscle.
Our Smart Adjustment: If you provide height and are overweight, we automatically substitute "Actual Weight" with "Adjusted Body Weight" to ensure the CrCl isn't falsely elevated.
Clinical Significance
Avoiding Toxicity
Kidneys clear drugs from the body. If clearance is slow (low CrCl), the drug stays in the blood longer. If you take the next dose too soon, drug levels can rise to toxic levels.
Common drugs requiring adjustment: Antibiotics, Digoxin, Lithium, NOACs.
Tracking Progression
For patients with chronic kidney disease, CrCl is tracked over months and years. A sudden drop can indicate acute kidney injury (AKI) or dehydration, requiring immediate intervention.
Trusted by Thousands for 100+ Free Online Tools
Join a growing community of creators, developers, and businesses who rely on our all-in-one tools platform for secure, fast, and free online tools. Your trust is our top priority—no sign-ups, no hidden costs, and complete privacy.
Frequently Asked Questions
Is CrCl the same as GFR?
Not exactly. GFR measures actual filtration. CrCl estimates it based on creatinine excretion. CrCl tends to slightly overestimate GFR, but it is still the preferred number for drug dosing guidelines.
Why do I need height?
Height allows us to calculate Ideal Body Weight. Using total weight for obese patients results in a falsely high CrCl, which could lead to an overdose. Height corrects this.
How do I know my Creatinine?
This requires a blood test (BMP or CMP panel). You cannot measure it at home. It is a standard part of annual checkups.
Does diet affect the result?
Yes. Eating a lot of cooked meat can temporarily raise serum creatinine. Extreme vegan diets might lower it. Muscle mass also affects it (bodybuilders have higher baseline creatinine).