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Creatinine Clearance Calculator

Estimate kidney creatinine clearance.

How it is calculated

This is the Cockcroft-Gault estimate of creatinine clearance: CrCl = (140 − age) × weight × k ÷ (72 × creatinine). Age is in years, weight in kilograms, serum creatinine in mg/dL, and the result is in mL/min. The sex factor k is 1 for men and 0.85 for women. Age, weight and creatinine must all be above zero. The formula uses the actual body weight you enter, with no correction for obesity or oedema, and it gives an estimate for people with stable kidney function. It is not the same as eGFR from CKD-EPI or MDRD, which are indexed to body surface area and give different numbers.

Worked example

A 62-year-old woman weighs 68 kg with serum creatinine 1.1 mg/dL. Age term: 140 − 62 = 78. Multiply by weight: 78 × 68 = 5,304. Apply the female factor: 5,304 × 0.85 = 4,508.4. Denominator: 72 × 1.1 = 79.2. Divide: 4,508.4 ÷ 79.2 gives 56.92 mL/min.

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Common mistakes

  • Entering creatinine in µmol/L. The field expects mg/dL; a value around 100 would give a near-zero clearance.
  • Entering weight in pounds instead of kilograms.
  • Choosing the wrong sex. The 0.85 factor for women lowers the result by 15%, so a mix-up is a large error.
  • Comparing the number with eGFR thresholds. Cockcroft-Gault is in mL/min and not indexed to body surface area, so it is not interchangeable with eGFR in mL/min/1.73 m².
  • Using it when creatinine is changing quickly, such as in acute kidney injury, where any steady-state formula is unreliable.

About this calculator

This calculator estimates creatinine clearance (CrCl), a measure of kidney filtering function, using the Cockcroft-Gault formula: CrCl = [(140 − age) × weight(kg) × (0.85 if female)] ÷ (72 × serum creatinine mg/dL). It approximates the glomerular filtration rate by relating how quickly the kidneys clear creatinine — a waste product from muscle metabolism — from the blood, adjusted for age, sex, and body weight since muscle mass (and thus baseline creatinine production) varies by these factors.

Physicians and hospital pharmacists rely on Cockcroft-Gault primarily for renal drug dosing — many medications (including common antibiotics, anticoagulants, and chemotherapy agents) must be dose-adjusted based on kidney function to avoid toxic accumulation, and this formula remains the historical reference standard baked into most drug-label dosing tables, even though newer eGFR equations (like CKD-EPI) are now preferred for general kidney-disease staging. Enter age, weight, sex, and serum creatinine to estimate CrCl.

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