Creatinine Clearance Calculator
Creatinine clearance
– mL/min
Enter age, weight and serum creatinine.
- Weight used
- –
- Creatinine
- –
The working
This works out the arithmetic. The order, the product in your hand and local policy still govern what is given.
The Cockcroft-Gault formula
CrCl (mL/min) = (140 − age) × weight in kg ÷ (72 × serum creatinine in mg/dL), × 0.85 if female
A 60-year-old man weighing 70 kg with a creatinine of 1.0 mg/dL comes out at 77.8 mL/min. The same figures for a woman give 66.1 mL/min, because the equation carries a 0.85 factor that reflects the lower average muscle mass behind the same creatinine reading.
Creatinine in µmol/L is divided by 88.4 before it enters the equation. The calculator does that step and shows it, so an SI result can be checked against a reference printed in conventional units.
Which weight to use in Cockcroft-Gault
This is the choice that moves the answer most, and it is the one most calculators make for you without saying. Cockcroft and Gault derived the equation against actual body weight. Renal dosing references frequently specify ideal or adjusted weight instead, because creatinine is produced by muscle and adipose tissue contributes little, so actual weight can read high in obesity.
A 55-year-old man, 170 cm tall, weighing 130 kg, with a creatinine of 1.1 mg/dL:
| Weight used | Value | Estimated CrCl |
|---|---|---|
| Actual body weight | 130 kg | 139.5 mL/min |
| Adjusted body weight | 91.6 kg | 98.3 mL/min |
| Ideal body weight | 65.9 kg | 70.8 mL/min |
Those are the same patient and the same blood test. Which of the three is right is set by the dosing source you are following, not by the arithmetic, which is why the calculator asks rather than choosing. Theideal body weight calculator works the two derived figures out on their own.
Creatinine clearance and eGFR are different numbers
Both estimate kidney function and they are routinely confused, but they are not interchangeable. Cockcroft-Gault gives creatinine clearance in mL/min for the person in front of you. An eGFR equation gives mL/min/1.73 m², normalised to a standard body surface area so that results compare across people of different sizes.
The practical consequence is that a lab report and a drug dosing table can disagree about the same patient while both being correct. Drug monographs that were written against Cockcroft-Gault expect the un-normalised figure, which is why this page does not normalise it. TheeGFR calculator runs the CKD-EPI 2021 equation for the other one.
Questions about creatinine clearance
- What is the Cockcroft-Gault formula?
- Creatinine clearance in mL/min equals 140 minus the age in years, multiplied by the body weight in kilograms, divided by 72 times the serum creatinine in mg/dL. The result is multiplied by 0.85 for a female patient.
- Which body weight should I use in Cockcroft-Gault?
- The equation was derived using actual body weight, and that remains the default. Many renal dosing references specify ideal or adjusted body weight instead, particularly in obesity, where actual weight can overestimate clearance substantially. Follow whichever weight the dosing source you are working from names.
- Is creatinine clearance the same as eGFR?
- No. Cockcroft-Gault estimates creatinine clearance in mL/min and is not adjusted for body size. eGFR equations such as CKD-EPI report mL/min/1.73 m², normalised to a standard body surface area. The two numbers are not interchangeable, and drug dosing tables usually name which one they expect.
- What is a normal creatinine clearance?
- Roughly 90 to 140 mL/min in healthy adult men and 80 to 125 mL/min in healthy adult women, falling with age. The figure is an estimate rather than a measurement, and it is unreliable where creatinine is changing rapidly, as in acute kidney injury.
- How do I convert creatinine from µmol/L to mg/dL?
- Divide by 88.4. So 88.4 µmol/L is 1.0 mg/dL, and 150 µmol/L is about 1.7 mg/dL.