About the Creatinine Clearance Calculator
This creatinine clearance calculator estimates kidney function with the Cockcroft-Gault equation, the formula most drug labels use for renal dose adjustment. Enter age, sex, weight, height and serum creatinine (in mg/dL or µmol/L) and it returns creatinine clearance (CrCl) in mL/min using actual, ideal and adjusted body weight, plus a recommended value based on common pharmacy practice.
It is intended for pharmacists, nurses, prescribers and students checking whether a medicine such as an antibiotic, anticoagulant or diabetes drug needs a lower dose, and for patients curious about the number on their chart. Height is needed to work out ideal body weight (Devine formula); the calculator uses actual weight if you are below ideal weight, ideal weight if you are within 120% of it, and adjusted weight above that.
Cockcroft-Gault is an estimate. It is less reliable in unstable kidney function, extremes of age or muscle mass, amputations, pregnancy and very low creatinine values. Lab eGFR (CKD-EPI) is used to stage chronic kidney disease; always follow your local dosing references.
With the default inputs, the creatinine clearance (recommended weight) is 78.3 mL/min. Change any value above to recalculate instantly.
How to use the creatinine clearance calculator
- 1Select sex and enter age.
- 2Enter weight and height in metric or imperial units.
- 3Enter serum creatinine and choose mg/dL or µmol/L.
- 4Read the recommended CrCl and check the actual, ideal and adjusted versions.
- 5Compare with the renal dosing thresholds in the drug’s label or your formulary.
Formula and method
Cockcroft and Gault (1976) derived this estimate of creatinine clearance in mL/min from age in years, weight in kilograms and serum creatinine (SCr) in mg/dL; results for women are multiplied by 0.85 to reflect lower average muscle mass. Creatinine in µmol/L is divided by 88.4 to convert to mg/dL.
Ideal body weight uses the Devine formula: 50 kg (men) or 45.5 kg (women) plus 2.3 kg per inch over 5 feet. Adjusted body weight is IBW + 0.4 × (actual − IBW). The recommended value uses actual weight when it is below IBW, IBW when actual weight is up to 120% of IBW, and adjusted weight above that — a common approach in pharmacy dosing, though protocols vary.
- CrCl
- Creatinine clearance, mL/min
- SCr
- Serum creatinine, mg/dL
- IBW
- Ideal body weight (Devine), kg
- AdjBW
- Adjusted body weight, kg
Worked examples
60-year-old man, 80 kg, 175 cm, SCr 1.0 mg/dL
Ideal body weight is 50 + 2.3 × (68.9 − 60) = 70.5 kg. Actual weight is 114% of ideal, so IBW is used: (140 − 60) × 70.5 ÷ (72 × 1.0) = 78.3 mL/min. Using actual weight would give 88.9 mL/min.
75-year-old woman, 60 kg, 160 cm, creatinine 106 µmol/L
106 µmol/L ÷ 88.4 = 1.2 mg/dL. Her IBW is 45.5 + 2.3 × (63.0 − 60) = 52.4 kg and she is 115% of it, so IBW applies: (140 − 75) × 52.4 ÷ (72 × 1.2) × 0.85 = 33.5 mL/min, in the moderately reduced range.
Obese man, 130 kg, 178 cm, SCr 1.2 mg/dL, age 50
IBW is 73.2 kg and actual weight is 178% of it, so adjusted weight 73.2 + 0.4 × (130 − 73.2) = 95.9 kg is used: (140 − 50) × 95.9 ÷ (72 × 1.2) = 99.9 mL/min. Actual weight would overstate clearance at 135 mL/min.
Frequently asked questions
What is a normal creatinine clearance?+
Normal creatinine clearance in healthy young adults is roughly 90–140 mL/min for men and 80–125 mL/min for women. It declines with age by about 1 mL/min per year after around 40.
What is the difference between CrCl and eGFR?+
CrCl from Cockcroft-Gault estimates creatinine clearance in mL/min and depends on body weight. eGFR (CKD-EPI) is normalised to 1.73 m² body surface area and is used to stage chronic kidney disease. Many drug labels were developed with Cockcroft-Gault.
Which weight should I use in Cockcroft-Gault?+
Practice varies. A common approach is actual weight if below ideal weight, ideal weight if within 120% of ideal, and adjusted body weight (IBW + 0.4 × excess) in obesity. Always follow your institution’s protocol.
Why is the result multiplied by 0.85 for women?+
Women have on average less muscle mass than men of the same weight, so they produce less creatinine. The 0.85 factor in the original Cockcroft-Gault study corrects for this difference.
When is Cockcroft-Gault not accurate?+
It is unreliable when kidney function is changing rapidly (acute kidney injury), in very muscular or very frail people, amputees, pregnancy, children and people with very low creatinine. A measured 24-hour urine clearance may be needed.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.