Creatinine Clearance — Cockcroft-Gault
Calculate creatinine clearance (CrCl) with the validated Cockcroft-Gault equation. Enter age, weight, serum creatinine and sex for kidney function in mL/min.
CalcVita. (2026). Creatinine Clearance — Cockcroft-Gault. CalcVita. Retrieved June 4, 2026, from https://calcvita.com/en/calculators/creatinine-clearance
How to use the creatinine clearance calculator
Enter your age (years), body weight (kg or lb), serum creatinine (mg/dL or µmol/L from a blood test), and biological sex. The calculator applies the Cockcroft-Gault equation to estimate your creatinine clearance in mL/min. Results are displayed with a kidney function category and clinical interpretation. Use actual body weight for most patients; for obese patients, consult your prescriber about adjusted body weight.
The Cockcroft-Gault equation explained
CrCl (mL/min) = ((140 − age) × weight [kg] × [0.85 if female]) ÷ (72 × serum creatinine [mg/dL]). Published by Cockcroft DW and Gault MH in Nephron (1976, 16:31–41), derived from 249 patients with stable renal function. The sex correction factor (0.85 for women) accounts for lower average muscle mass. Despite being nearly 50 years old, this equation remains the standard for pharmaceutical drug dosing because most drug pharmacokinetic studies used it to define renal dosing categories.
Drug dosing in renal impairment
CrCl thresholds commonly used in drug labeling: CrCl ≥ 50 mL/min — usually no adjustment needed; CrCl 30–49 mL/min — dose reduction often required (e.g., metformin, gabapentin, many antibiotics); CrCl 15–29 mL/min — significant dose adjustment or avoidance (e.g., NSAIDs, some anticoagulants); CrCl < 15 mL/min — most renally-cleared drugs require specialist oversight. Always verify current prescribing information — thresholds vary by drug and indication.
Normal values by age and sex
Average CrCl by age group (mL/min): Age 20–30: men 100–130, women 85–115. Age 40–50: men 85–110, women 70–95. Age 60–70: men 65–85, women 55–75. Age 70+: men 50–70, women 40–60. These are population averages — individual values vary significantly based on muscle mass, hydration, and comorbidities. Declining CrCl with age is physiologically normal; the rate of decline accelerates with diabetes, hypertension, and cardiovascular disease.
Scientific References
- Cockcroft DW, Gault MH. (1976). Prediction of creatinine clearance from serum creatinine. Nephron 16(1):31–41. PMID: 1244564
- National Kidney Foundation. (2023). KDOQI Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification. Am J Kidney Dis 39(Suppl 1):S1–S266.
- Levey AS, Stevens LA, Schmid CH, et al. (2009). A new equation to estimate glomerular filtration rate. Ann Intern Med 150(9):604–612. PMID: 19414839
- Dowling TC, Matzke GR, Murphy JE, Burckart GJ. (2010). Evaluation of renal drug dosing: prescribing information and clinical pharmacist approaches. Pharmacotherapy 30(8):776–786. PMID: 20653349
- What is creatinine clearance (CrCl)?
- Creatinine clearance (CrCl) is an estimate of the glomerular filtration rate (GFR) calculated from serum creatinine, using the Cockcroft-Gault equation. It reflects how much blood the kidneys clear of creatinine per minute (mL/min). Unlike eGFR (which is normalized to 1.73 m² body surface area), CrCl is an absolute value that depends on actual body size, making it especially useful for drug dosing decisions in renal impairment.
- What is the Cockcroft-Gault equation?
- The Cockcroft-Gault equation (1976) calculates creatinine clearance as: CrCl = ((140 − age) × weight × [0.85 if female]) / (72 × serum creatinine). Age is in years, weight in kg, and serum creatinine in mg/dL. The 0.85 female correction factor accounts for women having proportionally less muscle mass than men at the same weight. This formula is still the standard for drug dosing because most pharmacokinetic studies used it to define renal dosing categories.
- What is the difference between CrCl and eGFR?
- CrCl (Cockcroft-Gault) and eGFR (CKD-EPI) measure similar things but differ in key ways. eGFR is normalized to 1.73 m² body surface area and is the preferred metric for CKD staging and diagnosis per KDIGO guidelines. CrCl is absolute (not normalized) and is the standard metric referenced in drug prescribing information and clinical pharmacology studies. In practice, for an average-sized adult, CrCl and eGFR give similar values; they diverge significantly in very obese or very underweight patients.
- What weight should I use for the Cockcroft-Gault formula?
- The original Cockcroft-Gault formula uses actual body weight (ABW). However, clinical guidelines often recommend adjusted body weight (AdjBW) for obese patients, defined as: AdjBW = ideal body weight + 0.4 × (actual weight − ideal body weight). For patients at or below ideal body weight, use actual weight. For patients significantly above ideal weight, consult a clinical pharmacist, as overestimating CrCl in obese patients can lead to drug overdosing.
- What are normal creatinine clearance values?
- Normal CrCl varies by age and sex. In healthy young adults (20–30 years), CrCl is typically 100–130 mL/min in men and 85–115 mL/min in women. CrCl declines approximately 1 mL/min per year after age 40. Ranges: ≥ 90 mL/min (normal), 60–89 (mildly reduced), 30–59 (moderately reduced), 15–29 (severely reduced), < 15 (kidney failure). Drug dosing adjustments are typically triggered at CrCl < 50 or < 30 mL/min, depending on the medication.
- When should I see a doctor about my creatinine clearance?
- Consult your doctor if your CrCl is below 60 mL/min, especially if confirmed on repeat testing (> 3 months apart). CrCl below 30 mL/min (Stage 4–5 equivalent) requires urgent nephrology evaluation. All patients with reduced CrCl who take medications should have their doses reviewed, as many common drugs — including metformin, NSAIDs, antibiotics, anticoagulants, and diabetes medications — are contraindicated or require dose adjustment below certain CrCl thresholds. Never adjust medication doses based on this calculator alone — consult your healthcare provider.
Suggested article
Creatinine Clearance (CrCl): The Cockcroft-Gault Formula Explained
Creatinine clearance (CrCl) estimated by the Cockcroft-Gault equation is the pharmacokinetic standard for drug dosing in kidney disease. Learn how the formula works, why it differs from eGFR, how to choose the right body weight, and what CrCl thresholds matter for common medications.
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