Cockcroft-Gault Equation

Q: When should I use Cockcroft-Gault instead of CKD-EPI?

Use Cockcroft-Gault when adjusting medication doses, as many drug labels still reference CrCl from this equation.

Q: What weight should I use in the Cockcroft-Gault equation?

Use actual body weight by default. Adjusted body weight may be used in obese patients per institutional guidelines.

Estimates creatinine clearance (CrCl) for medication dosing using the Cockcroft-Gault equation.

Nephrology Internal MedicineEvidence-BasedUpdated 2026-08-06

Clinical Notes

Formula

CrCl = ((140 − age) × weight) / (72 × creatinine) × 0.85 (if female)

Normal Range

90–120 mL/min

Clinical Notes

Interpret results together with the patient's clinical presentation.

References

MedCalcHub Clinical References

Calculator Information

Specialty

Internal Medicine

📋 Reference Ranges

Normal Range

90–120 mL/min

Reference ranges for this calculator
Classification	Range
Normal renal function	≥90
Mild renal impairment	60–89
Moderate renal impairment	30–59
Severe renal impairment	15–29
Kidney failure	<15

What This Calculator Measures

Estimates creatinine clearance (CrCl) to guide drug dosing adjustments, particularly for renally cleared medications.

How to Use

Enter the patient's age, weight (kg), and serum creatinine (mg/dL).
Select the patient's sex.
Review the estimated creatinine clearance.

Interpretation Guide

CrCl >90 mL/min is normal. 60–89 is mildly decreased. 30–59 is moderately decreased. 15–29 is severely decreased. <15 indicates kidney failure. Use the result to adjust medication doses per drug-specific guidance.

Sex-specific interpretationAge-specific interpretation

Clinical Significance

The Cockcroft-Gault equation remains the most widely referenced method for drug dosing adjustments in renal impairment, as most drug labeling and pharmacokinetic studies used this equation for dose adjustments.

When to Use

Drug dosing for renally cleared medications (many antibiotics, anticoagulants, diabetes medications)
Situations where a medication label specifically requires Cockcroft-Gault CrCl
When eGFR-based dosing is not specified in drug labeling

When Not to Use

For CKD staging (use CKD-EPI eGFR instead)
In patients with rapidly changing renal function (use actual measured CrCl or consider real-time eGFR)
As a precise measure of GFR — it is an estimate

Limitations

Uses estimated rather than measured creatinine clearance.
Weight choice matters: actual, ideal, or adjusted body weight may be appropriate depending on clinical context.
Less accurate in obesity, extreme muscle mass, amputees, and unstable renal function.
Many drug dosing guidelines still reference Cockcroft-Gault despite its age.

Worked Example

A 70-year-old man weighing 75 kg has a serum creatinine of 1.4 mg/dL.

Inputs:

age: 70

weight: 75

creatinine: 1.4

sex: 1

CrCl ≈ (140 − 70) × 75 / (72 × 1.4) ≈ 52.1 mL/min. This indicates moderate renal impairment and may require dose adjustment for renally cleared drugs.

Evidence

Source: Nephrology / Pharmacy
Reference: Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16:31-41.
Reviewed By: MedCalcHub Clinical Team
Version: 1.0
Updated: 2026-08

Cockcroft DW, Gault MH. Nephron. 1976;16:31-41.

References

Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16:31-41. (Original Description)

Frequently Asked Questions

When should I use Cockcroft-Gault instead of CKD-EPI?

Use Cockcroft-Gault when adjusting medication doses, as many drug labels still reference CrCl from this equation.

What weight should I use in the Cockcroft-Gault equation?

Use actual body weight by default. Adjusted body weight may be used in obese patients per institutional guidelines.

Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Drug dosing decisions should always consider the individual patient's clinical context and current drug labeling.