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Creatinine Clearance Calculator

Source: Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41 · Source verified July 22, 2026

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

A creatinine clearance calculator estimates kidney function (specifically the glomerular filtration rate) using the Cockcroft-Gault formula, which incorporates a patient's age, sex, weight, and serum creatinine level. The result, expressed in mL/min, is used clinically to assess kidney health, stage chronic kidney disease, and adjust medication doses for drugs cleared by the kidneys. It remains a standard reference in FDA drug labeling despite the more recent CKD-EPI eGFR formula.

Estimate creatinine clearance (CrCl) for kidney function and drug dosing using the standard Cockcroft-Gault formula.

See also: BUN/Creatinine Ratio Calculator, Corrected Calcium Calculator, and AFT Calculator.

Quick Answer

Enter age, sex, weight, and serum creatinine to estimate creatinine clearance (CrCl) via the Cockcroft-Gault formula. Used for medication dosing and CKD staging.

Sex

Creatinine Clearance (CrCl)

Estimated CrCl

69.4 mL/min

Stage G2 — Mildly Decreased

Formula usedCockcroft-Gault

Stage G2: Mildly Decreased

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How it works

Formula · CrCl = ((140 − age) × weight kg × sex factor) / (72 × serum creatinine mg/dL); sex factor 1.0 male, 0.85 female

What is creatinine clearance?

Creatinine clearance (CrCl) is an estimate of how well your kidneys filter waste from your blood. Specifically, it measures the rate at which creatinine — a waste product from normal muscle breakdown — is cleared from the bloodstream by the kidneys.

CrCl is one of the most widely used measures of kidney function. It's used to diagnose and stage chronic kidney disease (CKD), adjust medication doses for drugs cleared by the kidneys, determine eligibility for certain medical procedures, and monitor kidney function over time.

The Cockcroft-Gault formula

The Cockcroft-Gault formula is the most commonly used method for estimating CrCl, especially for medication dosing decisions.

CrCl (mL/min) = [(140 − age) × weight (kg) × (0.85 if female)] / [72 × serum creatinine (mg/dL)]

For SI units (creatinine in μmol/L), the denominator is replaced by simply the serum creatinine value, and the sex multipliers become 1.04 for females and 1.23 for males.

CrCl vs. eGFR — what's the difference?

Both estimate kidney function. CrCl (Cockcroft-Gault) reports raw mL/min and is preferred for medication dosing because it matches FDA labeling. eGFR (CKD-EPI) reports mL/min per 1.73 m² (normalized for body size) and is preferred for CKD diagnosis and staging.

Interpreting your CrCl result

  • ≥ 90 mL/min: Normal or High (Stage G1)
  • 60-89 mL/min: Mildly Decreased (Stage G2)
  • 45-59 mL/min: Mildly to Moderately Decreased (Stage G3a)
  • 30-44 mL/min: Moderately to Severely Decreased (Stage G3b)
  • 15-29 mL/min: Severely Decreased (Stage G4)
  • < 15 mL/min: Kidney Failure (Stage G5)

Limitations and clinical considerations

The Cockcroft-Gault formula has several known limitations. It is not as accurate when kidney function is changing rapidly (acute kidney injury), at extremes of body weight, during pregnancy, or in patients with significant muscle wasting or extreme muscle mass.

Medical Disclaimer

This calculator provides estimates based on the Cockcroft-Gault formula. Results are for educational purposes only and not a substitute for medical advice, diagnosis, or treatment. Medication dosing and clinical decisions must be made by qualified healthcare providers.

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Frequently asked questions

CrCl is an estimate of how well your kidneys filter waste from your blood, expressed in milliliters per minute (mL/min). It's calculated from your age, sex, weight, and serum creatinine level using the Cockcroft-Gault formula. It's used to stage kidney disease and adjust medication doses for drugs cleared by the kidneys.

CrCl = [(140 − age) × weight in kg × (0.85 if female)] / (72 × serum creatinine in mg/dL). This formula, developed in 1976, estimates creatinine clearance and remains the standard for medication dosing decisions in clinical practice.

For healthy adults, normal CrCl is roughly 90-120 mL/min for men and 80-110 mL/min for women. CrCl naturally declines with age — by about 1 mL/min per year after age 40. A CrCl of 70 mL/min in a 75-year-old may be normal for that age, while it would be concerning in a 30-year-old.

Both estimate kidney function. CrCl (Cockcroft-Gault) reports raw mL/min and is preferred for medication dosing. eGFR (CKD-EPI 2021) reports mL/min per 1.73 m² (normalized for body size) and is preferred for CKD diagnosis and staging. They give similar but not identical results for the same patient.

Women typically have less muscle mass than men of the same age and weight, so they produce less creatinine. The Cockcroft-Gault formula multiplies the result by 0.85 for females to account for this. Without this adjustment, women's kidney function would be underestimated.

For most patients: actual body weight. For obese patients (>30% above ideal), using actual body weight may overestimate CrCl — many clinicians use adjusted body weight or ideal body weight in obese patients. For underweight or muscle-wasted patients, actual body weight may underestimate kidney function.

CrCl naturally declines with age, even in healthy people. From peak values around age 30, CrCl decreases by about 1 mL/min per year. By age 80, a normal CrCl might be 60-80 mL/min. This is why the formula uses (140 − age) as a starting point — it builds in the expected age-related decline.

Many drugs require renal dose adjustments, including: most antibiotics (especially aminoglycosides, vancomycin), digoxin, lithium, metformin, gabapentin, allopurinol, many cancer drugs, low-molecular-weight heparins, and direct oral anticoagulants (DOACs). Always check the drug label or institutional protocols for specific dosing.

Yes, particularly in early diabetes (hyperfiltration) or pregnancy (normal physiological increase). A very high CrCl (>140 mL/min) in a non-pregnant person may indicate early diabetic kidney disease and warrants further evaluation.

The Cockcroft-Gault formula is reasonably accurate (±20-30%) for most adults with stable kidney function. Accuracy decreases in extreme body weights, pregnancy, acute kidney injury, and significant muscle wasting. This calculator is for educational and planning purposes — clinical decisions should be made by qualified healthcare providers using the full clinical picture.