Creatinine Clearance (CrCl) Calculator

What this CrCl estimate represents

This calculator applies the Cockcroft–Gault equation to age, body weight, sex, and serum creatinine. It returns an estimated creatinine clearance (CrCl) in mL/min. The result is an equation-based estimate: it is not a timed urine measurement, measured GFR, or the body-surface-area-indexed eGFR commonly reported in mL/min/1.73 m².

The formula was published by Donald Cockcroft and Matthew Gault in 1976. In the conventional mg/dL form used here, the male-branch calculation is:

How the units and example work

Weight is entered in kilograms. Serum creatinine can be entered in mg/dL or μmol/L. With μmol/L selected, the entered value is divided by 88.4 before it is used in the formula. For example, 100 μmol/L becomes about 1.13 mg/dL.

Using the page’s sample values—male, age 45, weight 70 kg, and serum creatinine 100 μmol/L—the calculation is approximately ((140 − 45) × 70) ÷ (72 × 1.13), giving 81.6 mL/min after rounding. Selecting female for the same numbers applies the 0.85 factor and displays 69.4 mL/min. The displayed result is rounded to one decimal place.

Enter the values from the same clinical record

1. Choose the equation branch

   Select male or female to apply the corresponding Cockcroft–Gault branch. If you are checking a result for care, follow the clinician’s or prescribing reference’s instructions for this input.

2. Enter age and weight

   Enter age in years and weight in kg. The calculator uses the number entered as-is; it does not ask whether weight is actual, ideal, or adjusted, and it does not convert pounds to kilograms.

3. Match the creatinine unit

   Read the unit printed beside serum creatinine on the lab report, then choose the same unit in the calculator. Changing the unit selector only changes how the existing number is interpreted; it does not convert the number in the field. If you change from μmol/L to mg/dL, convert the value first.

4. Read and copy the result

   When each numeric entry is greater than zero, the estimate appears in mL/min and can be copied. Check the values and units before sharing or comparing the result.

Common CrCl calculation questions

Limits that affect interpretation

This calculator is for education and arithmetic checking. It does not diagnose kidney disease, assess prognosis, or recommend a medicine or dose.

• Cockcroft–Gault is an estimate, and serum creatinine equations can be less reliable when creatinine is changing or when body size or muscle mass is unusual. Ask a qualified professional which measure is appropriate for the situation.
• The form has male and female equation branches and does not provide an individualized way to select a branch. A health professional can help interpret the result when the branch is unclear.
• Age, weight, and creatinine are accepted when entered as positive numbers; the calculator does not check whether they fall within a clinically appropriate range. Implausible values can still produce a number.
• Do not use this result alone to stage CKD or make a dosing decision. NIDDK notes that medicine labels use a range of kidney-function measures and that estimates have limitations. Follow the current label and professional guidance.