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Calculator: Creatinine clearance estimate by Cockcroft-Gault equation in adults and older adolescents (age ≥16 years) (SI units)*

Calculator: Creatinine clearance estimate by Cockcroft-Gault equation in adults and older adolescents (age ≥16 years) (SI units)*

Sex Male (1)

Female (0.85)
Serum creatinine  

Important: Inputs must be complete to perform calculation.

Estimated creatinine clearance  
Decimal precision  


  • The Cockcroft-Gault equation was developed prior to the use of standardized creatinine assays and has not been updated for use with creatinine values reported with contemporary assay methods.[1] Thus, use of the Cockcroft-Gault equation with creatinine values measured by most laboratories in the United States today will result in a 10 to 40 percent overestimate of creatinine clearance.[2,3]
  • For drug dose adjustments in kidney impairment, the Cockcroft-Gault equation remains in use according to some published sources (eg, drug product labeling) and institutional protocols. However, many experts recommend using the most accurate method for estimating kidney function (eg, CKD-EPI equation or MDRD study equation) for drug dosing rather than the Cockcroft-Gault equation.[2,3]
  • Before using Cockcroft-Gault equation or another estimation of kidney function for drug dose adjustment, consult appropriate sources, including clinical drug reference(s), manufacturer’s labeling, and institutional protocols to avoid risk of overdosing, particularly for narrow therapeutic index drugs (eg, chemotherapeutic agents).
  • Kidney function must be stable to estimate creatinine clearance using this equation; Cockcroft-Gault equation does not provide accurate estimates when serum creatinine is rapidly changing (eg, hospitalized patients with acute kidney injury).
  • For patients at extremes of muscle mass (eg, those with amputation or muscle wasting), with unusual diets, or with conditions associated with changes in creatinine production or secretion, estimation equations that use serum creatinine have limited utility. The use of an alternative method of assessing kidney function may be necessary.
  • Refer to UpToDate topic reviews of assessment of kidney function for discussion of the accuracy of creatinine clearance as an estimate of true GFR and the use and limitations of Cockcroft-Gault and other GFR-estimating equations.
  • CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration; MDRD: Modification of Diet in Renal Disease; GFR: glomerular filtration rate; BMI: body mass index.
  • † Weight - Modifications of actual (total) body weight (eg, adjusted body weight, ideal body weight, or lean body weight) have been proposed to better quantify creatinine-producing muscle mass in patients with a high BMI. However, the use of body weight adjustment(s) is not standardized or universally accepted.[4] For guidance on whether to use an adjustment to the Weight input, refer to a clinical drug reference, manufacturer’s labeling, and institutional protocols. Separate calculators to estimate adjusted body weight, ideal body weight, and lean body weight for adult patients are available in UpToDate.
  • * This calculator uses SI units (Système international d'unités) as the default for inputs. Do not use this calculator if you are using conventional units (also known as US units and gravimetric units); please refer instead to the conventional units version of this calculator.

Equations used
Estimated_creatinine_clearance = (Sex * (140 - Age) * Weight * 1.23) / Serum_creatinine


Equation parameters, such as Sex, have two or more discrete values that may be used in the calculation. The numbers in the parentheses, eg, (1), represent the values that will be used.

  1. Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976; 16:31.
  2. Matzke GR, Aronoff GR, Atkinson AJ Jr, et al. Drug dosing consideration in patients with acute and chronic kidney disease-a clinical update from Kidney Disease: Improving Global Outcomes (KDIGO). Kidney Int 2011; 80:1122.
  3. National Kidney Foundation Inc. Cockcroft-Gault formula. Available at: (Accessed on December 15, 2021).
  4. National Institute of Diabetes and Digestive and Kidney Diseases. CKD & drug dosing: Information for providers - estimation of kidney function for prescription medication dosage in adults. Available at (Accessed on December 15, 2021).
Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

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