Creatinine Clearance Calculator (Cockcroft-Gault)

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Creatinine clearance calculator

Cockcroft-Gault creatinine clearance, as drug labels use it for renal dosing.

US unitsSI units

Creatinine clearance– mL/min

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The Cockcroft-Gault equation estimates creatinine clearance in mL/min:

CrCl = (140 - age) x weight in kg / (72 x serum creatinine in mg/dL), multiplied by 0.85 for women.

A 60-year-old man weighing 72 kg with a creatinine of 1.0 mg/dL has an estimated CrCl of 80 mL/min.

Why it is still used:

Drug dosing. Many drug labels, including those of the direct oral anticoagulants, several antibiotics and some chemotherapy, give renal dose adjustments by Cockcroft-Gault creatinine clearance, because their pharmacokinetic studies used it. Use the measure the label uses.
eGFR for staging kidney disease. For diagnosing and staging chronic kidney disease, KDIGO and US laboratories use eGFR from the race-free CKD-EPI 2021 equation, which is more accurate than Cockcroft-Gault in most adults (Inker, 2021).

Which weight to use matters. The equation was derived with actual body weight; in obesity, actual weight overestimates clearance, and ideal or adjusted body weight is often used. The calculator shows the result for each weight it can calculate.

Limitations and when not to use it

Creatinine must be stable. In acute kidney injury the result is not meaningful.
It assumes average muscle mass. It overestimates clearance in people with low muscle mass (frailty, amputation, cirrhosis, paralysis) and can underestimate it in very muscular people.
The equation came from 249 men; the 15% reduction for women was an assumption about muscle mass, not measured in women.
Creatinine assays have changed since 1976. Values from today's standardised (IDMS-traceable) assays are lower, so Cockcroft-Gault tends to give higher results than it did originally.
Not for children (use the bedside Schwartz equation) or pregnancy.

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Creatinine clearance (Cockcroft-Gault): common questions

Is creatinine clearance the same as eGFR?

No. Cockcroft-Gault estimates creatinine clearance in mL/min, unadjusted for body size; eGFR from CKD-EPI is in mL/min/1.73 m². They often differ, especially in older, smaller or obese patients.

Which body weight should I use?

The equation used actual weight. Many pharmacists use ideal body weight, or adjusted body weight when actual weight is well above ideal; follow your institution's policy and the drug label.

Why multiply by 0.85 for women?

To allow for lower average muscle mass and creatinine production. The original study included only men, so the factor was an estimate.

How do I convert creatinine from µmol/L?

Divide by 88.4 to get mg/dL. The calculator converts when you choose SI units.

References

Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749.
Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int. 2024;105(4S):S117-S314.
US Food and Drug Administration. Pharmacokinetics in Patients with Impaired Renal Function: Study Design, Data Analysis, and Impact on Dosing (draft guidance). 2020.

Last updated October 29, 2026 by 2 Minute Medicine. For healthcare professionals. A decision aid that supports, and never replaces, clinical judgment.