Creatinine Clearance (Cockcroft–Gault)

Methodology

Cockcroft–Gault (1976)

CrCl = (140 − age) × weight (kg) ÷ (72 × Scr mg/dL) × 0.85 [female]

Still specified in some medication dosing recommendations and product labelling, although other estimating equations are also used. Which weight to use is drug- and protocol-specific; all three are shown.

Who it is for

Adults with stable kidney function.

Version

1.0.1

How this calculator works

Where the formula comes from

• Cockcroft and Gault published the equation in 1976 to predict creatinine clearance in adult men from serum creatinine, stating that values for women are about 15% lower.^[1]
• It was derived from 24-hour creatinine excretion in 249 patients aged 18–92 and compared with measured creatinine clearance in 236 patients.^[1]

The inputs

• The inputs are age, body weight in kilograms, serum creatinine in mg/dL and sex; the original equation used actual body weight.^[1]

Versions and alternatives

• Using ideal or adjusted body weight instead of actual weight is a later adaptation. In one study of overweight and obese patients, adjusted body weight (IBW + 0.4 × excess weight) gave the least biased estimate among the weights compared.^[2]

Where accuracy falls (published evidence)

• The equation estimates creatinine clearance, not GFR, and its result is not indexed to body surface area.^[1]
• Cockcroft–Gault was developed before serum creatinine assays were standardised; with modern standardised creatinine measurements its estimates can differ from those with older methods, and are often higher.^[3][4]
• Like other creatinine-based equations, it is not reliable when creatinine is not at a steady state, such as during rapidly changing kidney function.^[5]
• In a study of people with diabetes and reduced kidney function, the error of Cockcroft–Gault was associated with body weight (BMI).^[6]

What guidelines say

• KDIGO 2024 notes that Cockcroft–Gault is still commonly used for drug dosing but has limitations, including development before creatinine standardisation.^[4]

Sources

1. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41. doi:10.1159/000180580
2. Winter MA, Guhr KN, Berg GM. Impact of various body weights and serum creatinine concentrations on the bias and accuracy of the Cockcroft-Gault equation. Pharmacotherapy. 2012;32(7):604–612. doi:10.1002/j.1875-9114.2012.01098.x
3. Carboplatin dosing in the era of IDMS-creatinine; the Cockroft-Gault formula no longer provides a reliable estimate of GFR. Gynecol Oncol. 2020. PMID 32220419
4. 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. doi:10.1016/j.kint.2023.10.018
5. Ullah S, et al. A model-based approach to assess unstable creatinine clearance in critically ill patients. Clin Pharmacol Ther. 2021;110(5):1240–1249. doi:10.1002/cpt.2341
6. Rigalleau V, et al. Cockcroft-Gault formula is biased by body weight in diabetic patients with renal impairment. Metabolism. 2006;55(1):108–112. doi:10.1016/j.metabol.2005.07.014

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on 2026-10-11

Worked example: how to calculate crCl (Cockcroft–Gault)

Calculation:

(80 × 80) / (72 × 1.2) = 74.07

An illustration with sample values, worked out with the same method the tool above uses.

Limitations

• Not standardized to body surface area and not equal to GFR.
• Overestimates with modern IDMS-standardized creatinine, especially at low values.
• Not reliable when serum creatinine is not at a steady state, such as during rapidly changing kidney function.

References

1. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41. doi:10.1159/000180580