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Creatinine clearance calculator

Free

Calculate creatinine clearance (CrCl) using the Cockcroft-Gault equation — the standard formula for drug dosing in renal impairment. Enter age, weight, sex and serum creatinine. All results must be verified before clinical use.

Age (years)

Sex

Male Female

Weight (kg)

Use ideal body weight if actual weight exceeds IBW. Calculate IBW

Serum creatinine

CrCl result

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Creatinine clearance: the Cockcroft-Gault equation explained

Cockcroft-Gault is the standard formula used for drug dosing in renal impairment. Published in 1976, it calculates an estimated creatinine clearance from 4 variables: age, sex, weight and serum creatinine.

The formula

CrCl (mL/min) = ((140 - age) × weight in kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 for female patients. The female correction accounts for lower muscle mass and therefore lower baseline creatinine production.

Which weight to use

For patients whose actual body weight is close to their ideal body weight, use actual weight. For obese patients (actual weight significantly exceeds IBW), use IBW instead — otherwise CrCl is overestimated. Use our Ideal Body Weight Calculator if needed.

CrCl vs eGFR

Cockcroft-Gault CrCl and CKD-EPI eGFR are different calculations that serve different purposes. CrCl is used for drug dosing because the vast majority of renal dosing guidelines were developed using Cockcroft-Gault data. eGFR (reported by labs) is used for CKD staging. Don't use eGFR for drug dosing — use our Renal Dose Adjustment Calculator alongside this CrCl result.

Frequently asked questions

What is the Cockcroft-Gault equation?

CrCl = ((140 - age) × weight in kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 for female patients. Published in 1976, it estimates the kidneys' ability to filter creatinine and is the standard for drug dose adjustment in renal impairment.

Should I use CrCl or eGFR for drug dosing?

Use Cockcroft-Gault CrCl for drug dosing. Most renal dosing guidelines were developed using this equation. The eGFR reported by labs uses the CKD-EPI formula, which gives different values — especially in elderly and obese patients. Using eGFR for dosing can lead to under- or over-dosing.

Why does gender affect CrCl?

Female patients typically have less muscle mass than male patients of the same age and weight, which means they produce less creatinine. A serum creatinine of 1.0 mg/dL therefore represents a lower GFR in a woman than in a man. The 0.85 correction factor in Cockcroft-Gault accounts for this difference.