What is the Cockcroft-Gault formula?

CrCl (mL/min) = [(140 − age) × weight (kg)] / [72 × serum creatinine (mg/dL)], multiplied by 0.85 for females. It was published by Cockcroft and Gault in 1976 and remains the standard for renal drug dosing.

Should I use actual, ideal, or adjusted body weight?

Most drug dosing guidelines specify which weight to use. This calculator uses actual body weight by default. For obese patients, many pharmacists use ideal body weight (IBW) or adjusted body weight (ABW). Consult the specific drug monograph.

How does CrCl differ from eGFR?

eGFR (CKD-EPI or MDRD) is standardized to body surface area and used for CKD staging. CrCl from Cockcroft-Gault is not BSA-adjusted and is the recommended metric for drug dosing by most regulatory agencies and package inserts.

What are normal CrCl values?

Normal CrCl is roughly 85–125 mL/min in healthy adults. Values decline with age, and a CrCl below 60 mL/min generally indicates moderate renal impairment and triggers dose adjustments for many drugs.

Why does CrCl decrease with age even if creatinine looks normal?

Elderly patients have less muscle mass, so they produce less creatinine. Serum creatinine may appear "normal" while true kidney function is substantially reduced. The Cockcroft-Gault age term captures this effect.

Is this calculator validated for pediatric patients?

No. The Cockcroft-Gault equation is validated for adults. Pediatric renal function is typically estimated with the Schwartz equation. Do not use this tool for patients under 18 years.

Cockcroft-Gault CrCl Calculator

Estimate creatinine clearance (mL/min) using the Cockcroft-Gault equation for kidney function and drug dosing adjustments.

Patient Parameters

Age (years)

Body Weight

Biological Sex

Serum Creatinine

Normal: 0.6–1.2 mg/dL (men), 0.5–1.1 mg/dL (women)

Fill in the patient parameters and click Calculate CrCl

Estimated CrCl

— mL/min

Function

—

0 30 60 90 120+

Formula Breakdown

Renal Function Reference

Category	CrCl (mL/min)	Description

Clinical note: This tool is for educational reference only. Always consult the specific drug monograph for dosing thresholds, and consider using ideal or adjusted body weight for obese patients as directed. Results do not replace clinical judgment.

Summary

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) as a surrogate for glomerular filtration rate (GFR). It uses age, body weight, sex, and serum creatinine to produce a result in mL/min. Clinicians rely on it to identify renal impairment and adjust medication doses for drugs that are renally cleared.

How it works

Enter the patient's age in years.
Enter actual body weight in kilograms (or toggle to lbs for auto-conversion).
Select biological sex — the female correction factor (×0.85) is applied automatically.
Enter serum creatinine in mg/dL (or toggle to µmol/L for auto-conversion).
CrCl (mL/min) is calculated instantly using the Cockcroft-Gault formula.
Review the renal function category and dosing guidance shown below the result.

Use cases

Dose-adjust renally cleared medications (e.g., vancomycin, metformin, direct oral anticoagulants).
Screen patients for renal impairment before prescribing nephrotoxic drugs.
Assess baseline renal function before contrast-enhanced imaging.
Monitor kidney function trends in patients with diabetes or hypertension.
Support pharmacokinetic calculations in clinical practice.
Guide appropriate drug selection in elderly patients with reduced muscle mass.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu