Creatinine Clearance Calculator
The creatinine clearance calculator estimates CrCl in mL/min using the Cockcroft-Gault formula, an estimate of how well your kidneys filter waste, and categorises the result.
verified_userReviewed by the Calculopedia editorial teamLast updated 2026-08-15
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- Age
- 40
- Gender
- male
- Weight
- 70
- Serum creatinine
- 1
Results
- Creatinine clearance
- 97.2
- Kidney function
- Normal (≥ 90 mL/min)
functionsThe formula
Creatinine clearance (CrCl) estimates how well your kidneys filter creatinine — a waste product of muscle metabolism. It's used to gauge kidney function and to dose drugs that are cleared by the kidneys.
What creatinine is and why it tracks kidney health
Creatinine is produced at a fairly steady rate as your muscles break down creatine, and your kidneys constantly filter it out of the blood. If kidney function drops, creatinine accumulates, so its level in the blood indirectly reflects how well the filter is working. The clever part is that blood creatinine alone is hard to interpret — a "high" value depends on your muscle mass — so these formulas combine it with age, weight and sex to produce a number in mL/min that describes the kidney's filtering capacity directly.
The Cockcroft-Gault formula
Men: CrCl = (140 − age) × weight(kg) ÷ (72 × serum creatinine mg/dL)
Women: same result × 0.85
This equation was published in 1976 by Donald Cockcroft and Henry Gault, who derived it by fitting data from hospital patients. It quickly became a standard because it needs only simple, cheap measurements, and it remains widely used — especially for dosing renally-cleared drugs, where an estimate matters more than waiting for a lab test.
Worked example
A 40-year-old man, 70 kg, serum creatinine 1.0 mg/dL:
CrCl = (140 − 40) × 70 ÷ (72 × 1.0) = 7,000 ÷ 72 ≈ 97.2 mL/min
A 40-year-old woman with the same numbers:
97.2 × 0.85 ≈ 82.6 mL/min
Reading the result (CKD stages)
| CrCl (mL/min) | Kidney function |
|---|---|
| ≥ 90 | Normal |
| 60–89 | Mildly reduced |
| 30–59 | Moderately reduced |
| 15–29 | Severely reduced |
| < 15 | Kidney failure |
These bands broadly align with the chronic kidney disease staging used in clinical practice, and are meant as orientation rather than a diagnosis.
Limitations
Cockcroft-Gault estimates creatinine clearance — it is not a direct measurement. Results are less accurate in very elderly, obese, or edematous patients, and other equations (MDRD, CKD-EPI) may be preferred. The 0.85 correction for women reflects their generally lower muscle mass and creatinine production. A single figure is also a snapshot — kidney function fluctuates, and serum creatinine responds to diet, hydration and muscle mass. Always have results interpreted by a clinician.
This tool is for general education and is not medical advice. Discuss any kidney-function results with your doctor.
helpFrequently asked questions
question_markHow is creatinine clearance calculated?
The Cockcroft-Gault formula estimates it: CrCl = (140 − age) × weight ÷ (72 × serum creatinine), multiplied by 0.85 for women. Results are in mL/min.
question_markWhat is a normal creatinine clearance?
Normal is roughly 90 mL/min or above for adults. Values of 60–89 are mildly reduced, and below 60 suggests progressively more significant kidney impairment.
question_markWhy multiply by 0.85 for women?
Women typically have less muscle mass and therefore lower creatinine production, so the formula applies a 15% reduction to avoid overestimating their clearance.
question_markIs creatinine clearance the same as GFR?
Not exactly. CrCl estimates creatinine filtration and is closely related to GFR, but modern practice often uses equations like CKD-EPI for estimated GFR. This calculator estimates CrCl only.