How to use it
- Choose sex and enter age in years (18 to 120).
- Choose metric or US units and enter weight and height. Height is used for ideal body weight.
- Choose the creatinine unit from your lab report and enter the value.
- Read creatinine clearance with actual, ideal and adjusted body weight.
Formulas
Cockcroft–Gault: CrCl (mL/min) = (140 − age) × weight (kg) ÷ (72 × creatinine in mg/dL), multiplied by 0.85 for females.
- Ideal body weight (Devine): 50 kg for males or 45.5 kg for females, plus 2.3 kg for every inch of height over 5 feet (60 in).
- Adjusted body weight: ideal weight + 0.4 × (actual weight − ideal weight).
- Creatinine in µmol/L is divided by 88.4; pounds and inches are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).
For people shorter than 5 feet the Devine formula gives less than the base weight; for very short heights, where it gives zero or less, the ideal and adjusted rows are left out.
Worked example
A 60-year-old man weighing 80 kg, 175 cm tall, with creatinine 1.2 mg/dL:
- Actual weight: (140 − 60) × 80 ÷ (72 × 1.2) = 6400 ÷ 86.4 = 74 mL/min.
- Ideal weight: 175 cm = 68.9 in, so 50 + 2.3 × 8.9 = 70.5 kg; 80 × 70.5 ÷ 86.4 = 65 mL/min.
- Adjusted weight: 70.5 + 0.4 × (80 − 70.5) = 74.3 kg; 80 × 74.3 ÷ 86.4 = 69 mL/min.
Limits and tips
- This is an estimate for information, not a diagnosis or a dosing decision. Dose adjustments come from the prescriber or pharmacist.
- The equation assumes stable creatinine. In acute kidney injury, after amputation, or with very low muscle mass the estimate can be far off.
- Some protocols round low creatinine values up (for example in older adults) before using the equation. This calculator uses the value exactly as entered.