Creatinine Clearance Calculator (Cockcroft-Gault Equation)
Estimate creatinine clearance using the Cockcroft-Gault equation to support kidney function assessment and drug dosing.
Creatinine Clearance Calculator
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This calculator is for informational and educational purposes. Results should be interpreted with clinical judgment and local guidelines.
What is Creatinine Clearance (CrCl)?
Creatinine clearance (CrCl) is a measure of how effectively the kidneys filter creatinine from the blood. It serves as a clinical estimate of the glomerular filtration rate (GFR) and is widely used to adjust medication doses in patients with impaired renal function. The Cockcroft-Gault equation estimates CrCl from serum creatinine, age, weight, and sex.
CrCl (mL/min) = [(140 − Age) × Weight (kg)] / [72 × Serum Creatinine (mg/dL)]. Multiply by 0.85 for females.
When to Use the Creatinine Clearance Calculator
- Drug dosing adjustment for renally-cleared medications (e.g., antibiotics, anticoagulants, chemotherapy, antivirals).
- Assessing kidney function before prescribing direct-acting oral anticoagulants (DOACs) — many DOAC labels specifically require Cockcroft-Gault CrCl.
- Evaluating renal function in elderly patients before surgery or contrast media administration.
- Monitoring kidney function trends over time in patients with chronic kidney disease (CKD).
- Pharmacokinetic calculations where drug labels reference Cockcroft-Gault CrCl rather than eGFR.
- ICU and critical care settings where rapid renal function estimation is needed for medication management.
Cockcroft-Gault Formula
Males
CrCl (mL/min) = [(140 − Age) × Weight (kg)] / [72 × Serum Creatinine (mg/dL)]
Example: [(140 − 60) × 70] / [72 × 1.2] = 5600 / 86.4 = 64.8 mL/min
Females
CrCl (mL/min) = [(140 − Age) × Weight (kg)] / [72 × Serum Creatinine (mg/dL)] × 0.85
Example: [(140 − 60) × 60] / [72 × 1.0] × 0.85 = 4800 / 72 × 0.85 = 56.7 mL/min
Variables
Age (years)
Patient age in years.
Weight (kg)
Actual body weight. Use ideal or adjusted weight for obese patients per institutional protocol.
Serum Creatinine (mg/dL)
Serum creatinine level from a recent blood test.
Sex (Male/Female)
A correction factor of 0.85 is applied for female patients.
The Cockcroft-Gault equation was published in 1976 and was developed using data from 249 male patients. It has not been re-derived for modern IDMS-standardized creatinine assays. Many drug labels still reference this equation, making it the standard for pharmacokinetic dose adjustments.
CrCl Interpretation & Kidney Function Staging
Creatinine clearance values correspond to kidney function stages. These ranges help guide drug dosing decisions.
| Range | Classification | Health Risk |
|---|---|---|
| > 90 mL/min | Normal Kidney Function | Standard dosing |
| 60 – 89 mL/min | Mild Impairment (CKD Stage 2) | Monitor function |
| 30 – 59 mL/min | Moderate Impairment (CKD Stage 3) | Dose reduction likely required |
| 15 – 29 mL/min | Severe Impairment (CKD Stage 4) | Significant dose reduction |
| < 15 mL/min | Kidney Failure (CKD Stage 5) | Dialysis-level; contraindication for many drugs |
CKD staging is officially based on eGFR (CKD-EPI equation), not Cockcroft-Gault CrCl. However, for drug dosing, many protocols still require CrCl. Always check the drug label to determine which renal function metric is required.
Limitations & Clinical Warnings
The Cockcroft-Gault equation was derived from a small, predominantly male cohort in 1976. It has not been validated for diverse modern populations.
It assumes a steady state of serum creatinine. It is unreliable in acute kidney injury (AKI), rapidly changing renal function, or critical illness.
The equation uses actual body weight, which can overestimate CrCl in obese patients and underestimate it in cachectic patients. Ideal body weight (IBW) or adjusted body weight (ABW) may be preferred — follow institutional protocol.
Modern IDMS-standardized creatinine assays produce lower serum creatinine values than older assays, which can inflate Cockcroft-Gault CrCl estimates.
Creatinine production depends on muscle mass. Low muscle mass (elderly, malnourished, amputees) can produce falsely normal serum creatinine and overestimate renal function.
Do not use in patients on dialysis, with rapidly changing creatinine, or in pregnant women without clinical context.
Medical Disclaimer
This calculator is for clinical reference only. Always verify drug dosing against current drug labels, institutional guidelines, and pharmacist review. CrCl calculations should be interpreted alongside the complete clinical picture including urine output, hydration status, and comorbidities.
References & Citations
- Cockcroft DW, Gault MH. “Prediction of creatinine clearance from serum creatinine”. Nephron. 1976. 16(1): 31-41. PMID: 1244564
- National Kidney Foundation. “K/DOQI Clinical Practice Guidelines for Chronic Kidney Disease”. American Journal of Kidney Diseases. 2002. 39(2 Suppl 1): S1-S266. PMID: 11904577
- KDIGO. “KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease”. Kidney International Supplements. 2013. 3(1): 1-150. DOI: 10.1038/kisup.2012.73
- Levey AS, Coresh J, Tighiouart H, et al.. “Measured and estimated glomerular filtration rate: current status and future directions”. Nature Reviews Nephrology. 2020. 16(1): 51-64. DOI: 10.1038/s41581-019-0191-y
Medically Reviewed
Reviewed by CliniqWise Clinical Advisory Board · Last updated: 2026-08-27 · Next review: 2027-02-27
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