CrCl Calculator — Creatinine Clearance (Cockcroft-Gault)
Estimate creatinine clearance (CrCl) in mL/min from age, weight, serum creatinine and sex using the Cockcroft-Gault formula — the standard method for drug-dosing adjustments and CKD staging.
years
kg
mg/dL
Biological sex
mL/min — estimated by the Cockcroft-Gault formula
- 1
Numerator: (140 − age) × weight
(140 − 45) × 70 = 6,650 - 2
Denominator: 72 × serum creatinine
72 × 1 = 72 - 3
Raw CrCl (male baseline)
6,650 ÷ 72 = 92.36 - 4
Apply sex correction factor
92.36 × 1.00 = 92.4No correction applied for male sex.
How does this calculator work?
CrCl (mL/min) = [(140 − age) × weight kg / (72 × SCr mg/dL)] × 0.85 for females. Enter age, weight, serum creatinine and sex to get the estimated filtration rate and CKD stage (G1–G5). Used clinically to adjust drug doses in renal impairment — results should always be reviewed by a clinician.
Formula
How this is calculated
The Cockcroft-Gault equation, published in 1976, estimates how many millilitres of blood the kidneys filter per minute from three patient characteristics: age (kidney function naturally declines with age), body weight (a proxy for muscle mass, which determines creatinine production rate), and serum creatinine (SCr — the waste product the kidneys excrete). Female sex applies a 0.85 correction because women generally have less muscle mass and therefore lower creatinine production for the same body weight.
The result maps to KDIGO CKD stages: ≥ 90 mL/min (G1 – normal or high), 60–89 (G2 – mildly decreased), 30–59 (G3 – moderately decreased), 15–29 (G4 – severely decreased), < 15 (G5 – kidney failure). These thresholds guide drug-dose reductions — many antibiotics, anticoagulants and diabetes drugs require adjustment below 50 or 30 mL/min.
Important limitations: Cockcroft-Gault uses actual body weight; in obese patients, clinical pharmacists often substitute ideal or adjusted body weight, which this calculator does not do. The equation also tends to overestimate CrCl in elderly or very thin patients and underestimate it at high muscle mass. The CKD-EPI equation is now preferred for CKD staging; Cockcroft-Gault remains widely used specifically for drug dosing. Always interpret results in clinical context with a qualified clinician.
Frequently asked questions
Creatinine clearance (CrCl) estimates the volume of blood the kidneys filter per minute. It reflects overall kidney function and is the standard basis for adjusting doses of renally-cleared drugs — antibiotics, anticoagulants, chemotherapy — to avoid toxicity in patients with reduced kidney function.
Divide the µmol/L value by 88.4 to get mg/dL. For example, 100 µmol/L ÷ 88.4 ≈ 1.13 mg/dL. US laboratories report creatinine in mg/dL; most of the world uses µmol/L.
Both estimate the kidney filtration rate. Cockcroft-Gault CrCl is used primarily for drug dosing adjustments. eGFR from the CKD-EPI equation is the preferred measure for diagnosing and staging chronic kidney disease. They usually give similar numbers but diverge at extremes of age, weight or muscle mass.
Also known as
TG we-Calculate Editorial Team. (2026). CrCl Calculator — Creatinine Clearance (Cockcroft-Gault) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/crcl-calculator
TG we-Calculate Editorial Team. "CrCl Calculator — Creatinine Clearance (Cockcroft-Gault)." TG we-Calculate. 2026. https://we-calculate.com/calculator/crcl-calculator.
TG we-Calculate Editorial Team, "CrCl Calculator — Creatinine Clearance (Cockcroft-Gault)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/crcl-calculator
@misc{wecalculate_crcl_calculator, title = {CrCl Calculator — Creatinine Clearance (Cockcroft-Gault)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/crcl-calculator}}, year = {2026}, note = {TG we-Calculate} }
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