For healthcare professionals
Creatinine clearance calculator (Cockcroft-Gault)
The Cockcroft-Gault equation estimates creatinine clearance in mL/min from age, body weight, sex and serum creatinine. Many drug labels still state kidney dose adjustments in terms of Cockcroft-Gault creatinine clearance. This calculator is written for clinicians. It is not a test for kidney disease, which is staged with eGFR.
Patient values
Adults. Nothing you enter leaves this page.
What you will see
The estimated creatinine clearance in mL/min, with the working shown.
Educational only, not medical advice. Not a diagnosis. Use the drug label's own thresholds for dosing.
Source
Cockcroft DW and Gault MH, Nephron 1976, for the formula and the 15% lower value in females; the equation as printed in FDA-approved labeling (SAVAYSA prescribing information, section 2.1, on DailyMed). The tests check worked examples from that equation.
Validated in
Derived from the relationship between age and 24-hour creatinine excretion per kg in 249 adult patients aged 18 to 92, then compared with the mean of two measured 24-hour creatinine clearances in 236 patients (correlation 0.83). The formula was developed for adult males, with values 15% less in females (Cockcroft 1976).
Limits
An estimate of creatinine clearance, not a measured GFR, and not adjusted to body surface area. Serum creatinine also depends on muscle mass, body size, diet and tubular secretion. Body weight choice changes the result: in overweight or obese adults, FDA guidance says ideal or adjusted body weight is likely more accurate than actual weight. Not for staging chronic kidney disease, for children, or when creatinine is changing quickly.
The Cockcroft-Gault equation
Creatinine clearance (mL/min) = (140 − age) × weight in kg × (0.85 if female) / (72 × serum creatinine in mg/dL) (FDA label).
Cockcroft and Gault developed the formula for adult males and gave values 15% less for females, which is the 0.85 factor (Cockcroft 1976). To enter creatinine in µmol/L, the calculator divides by 88.4 to convert to mg/dL. The result is in mL/min for the individual, not mL/min/1.73 m², because body weight is already in the equation.
Which body weight to use
The original formula uses body weight in kg (Cockcroft 1976). FDA guidance on renal impairment studies says that in overweight or obese individuals, using ideal body weight or adjusted body weight in the Cockcroft-Gault equation is likely to give a more accurate estimate of kidney function than actual body weight (FDA 2024). Some drug labels name the weight to use; follow the label where it does.
Creatinine clearance and drug dosing
FDA-approved drug labels base kidney dose adjustments on different measures: measured creatinine clearance, Cockcroft-Gault estimated creatinine clearance, or eGFR from the MDRD Study or CKD-EPI equations. Labels for drugs developed before 2005 may predate standardized creatinine assays (NIDDK). NIDDK notes that the FDA does not recommend one estimating equation over another for dose adjustment, and that across most patients and drugs the choice of equation made little difference to the recommended dose in a 2009 simulation study (NIDDK).
When a result sits close to a label's cut point, or the drug has a narrow therapeutic index, NIDDK suggests considering cystatin C based eGFR, a measured creatinine clearance, or measured GFR, especially in people with a very large or very small body size (NIDDK).
FDA guidance groups kidney function for dedicated renal impairment studies as 90 mL/min or more (control), 60 to under 90 (mild), 30 to under 60 (moderate) and under 30 (severe or kidney failure not on dialysis). It states that this grouping is only for designing those studies and not for classifying kidney disease (FDA 2024).
Creatinine clearance is not eGFR
Chronic kidney disease is staged with eGFR in mL/min/1.73 m² together with urine albumin, using the G1 to G5 and A1 to A3 categories (KDIGO 2024). NIDDK points to the CKD-EPI equations, notably the 2021 versions, as the newest (NIDDK). For staging, use the eGFR calculator (CKD-EPI 2021) and the urine albumin-to-creatinine ratio calculator; how the two combine is in kidney disease stages, explained.
Related tools
The MELD score calculator also uses serum creatinine. For people without lab results yet, the kidney disease risk score (SCORED) shows whether kidney testing is worth asking about.
Sources
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41. doi:10.1159/000180580. PMID 1244564. Abstract. pubmed.ncbi.nlm.nih.gov/1244564/
- SAVAYSA (edoxaban) tablets, FDA-approved prescribing information, section 2.1 (Cockcroft-Gault equation as printed in the label). DailyMed, U.S. National Library of Medicine, set ID e77d3400-56ad-11e3-949a-0800200c9a66. dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e77d3400-56ad-11e3-949a-0800200c9a66
- U.S. Food and Drug Administration. Pharmacokinetics in Patients with Impaired Renal Function: Study Design, Data Analysis, and Impact on Dosing. Guidance for Industry. March 2024. Section IV.A and Table 1. www.fda.gov/media/78573/download
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). CKD and Drug Dosing: Information for Providers. Last reviewed October 2024. www.niddk.nih.gov/research-funding/research-programs/kidney-clinical-research-epidemiology/laboratory/ckd-drug-dosing-providers
- 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.org/10.1016/j.kint.2023.10.018
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-01. Spotted an error? See About.