Actual measured body weight. The weight basis selector below decides what the equation uses.
Switch to µmol/L if your lab reports SI units. 88.4 µmol/L is 1.0 mg/dL.
Only needed for ideal or adjusted body weight.
What the 1976 paper was derived on.
The equation, and where it comes from
CrCl = [(140 - age) x weight in kg x (0.85 if female)] / (72 x serum creatinine in mg/dL)
Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
How to read the result
Cockcroft-Gault estimates a clearance in mL/min. It is an estimate of kidney function, not a dose: it predates modern creatinine assay standardisation and tends to differ from CKD-EPI eGFR, particularly at the extremes of body weight.
Your patient's numbers never leave this device
The creatinine clearance arithmetic runs in JavaScript inside your own browser. There is no server call when you type, nothing is written to a database, nothing is logged, and no account is involved. Once the page has loaded you can disconnect from the network and it still works.
That matters more here than on an ordinary calculator. Values entered on a hospital workstation come off a real chart, and this tool deliberately does not remember them: close the tab and they are gone, including for the next person who uses that machine.
Frequently asked questions
- What is the Cockcroft-Gault equation?
- CrCl = [(140 - age) x weight in kg] / (72 x serum creatinine in mg/dL), multiplied by 0.85 for women. It was published by Cockcroft and Gault in Nephron in 1976 from 249 adult men, and the 0.85 factor accounts for lower average muscle mass.
- Should I use actual, ideal or adjusted body weight?
- The original equation was derived on actual body weight, so that is the default here. Ideal and adjusted body weight are widely used in obesity because fat mass does not generate creatinine, and using actual weight in a very heavy patient overestimates clearance. This calculator offers all three and tells you which weight it used.
- How does creatinine clearance differ from eGFR?
- Cockcroft-Gault estimates creatinine clearance in mL/min and is not indexed to body surface area. CKD-EPI and MDRD estimate glomerular filtration rate in mL/min per 1.73 m². The numbers are not interchangeable, and the two can diverge substantially in people who are very large, very small, or elderly.
- My lab reports creatinine in µmol/L. Can I use that?
- Yes. Switch the creatinine unit to µmol/L and the value is converted to mg/dL for you before the equation runs: divide by 88.4 to reach mg/dL. The clearance is reported in mL/min either way, since Cockcroft-Gault is not indexed to body surface area. Entering an SI value into a field expecting mg/dL is one of the more common ways these calculators are misused, which is why the switcher is there rather than a footnote.
- Is this valid in children?
- No. Cockcroft-Gault was derived in adults and the calculator flags a warning if you enter an age under 18. Paediatric estimates use different equations built for growing children.