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This free creatinine clearance calculator, developed by Rology, uses the Cockcroft-Gault equation to estimate a patient's creatinine clearance (CrCl) in mL/min. Enter the patient's sex, age, weight, and serum creatinine, and the tool returns an estimated CrCl value along with KDIGO-mapped staging and practical guidance for contrast-enhanced imaging.
The Cockcroft-Gault formula estimates creatinine clearance as [(140 − age) × weight (kg)] / (72 × serum creatinine (mg/dL)), multiplied by 0.85 for female patients.
Because it incorporates age, body weight, and serum creatinine, the Cockcroft-Gault equation remains one of the most widely used bedside methods for gauging renal function when a rapid estimate is needed rather than a formal measured clearance.
This calculator is designed for radiographers, radiologists, and imaging teams who need to assess renal function before administering iodinated or gadolinium-based contrast media. Estimating CrCl helps identify patients at higher risk of contrast-associated kidney injury, supports safe contrast-dosing decisions, and reinforces sound clinical judgement as part of a wider pre-scan safety check. It is intended to support—not replace—clinical assessment and local contrast-safety protocols.
Rology is a health technology company focused on improving access to high-quality radiology services through teleradiology, AI-enabled solutions, and digital imaging tools. Rology supports hospitals, imaging centers, radiologists, and healthcare teams with technology designed to make radiology workflows faster, more accessible, and more efficient.
A creatinine clearance calculator estimates how efficiently the kidneys are filtering creatinine from the blood, reported in mL/min. This tool uses the Cockcroft-Gault equation, combining age, weight, sex, and serum creatinine to produce a fast estimate of renal function at the point of care.
CrCl (creatinine clearance) from the Cockcroft-Gault equation estimates clearance in mL/min and is weight-based, which is why it is often used for drug and contrast dosing. eGFR (estimated glomerular filtration rate), usually from the CKD-EPI or MDRD equations, is normalised to body surface area and reported in mL/min/1.73m². The two values can differ, especially at extremes of body weight, so the appropriate measure depends on the clinical purpose.
Reduced renal function increases the risk of contrast-associated acute kidney injury. Estimating CrCl before contrast-enhanced CT or MRI helps imaging teams flag higher-risk patients, choose appropriate contrast agents and volumes, and follow local safety protocols.
You need the patient's sex, age in years, body weight, and a recent serum creatinine result. Entering these values returns an estimated creatinine clearance along with KDIGO-aligned staging and contrast-safety guidance.
No. The Cockcroft-Gault estimate is a screening aid. It should be interpreted alongside the full clinical picture, local guidelines, and specialist input where needed, and does not replace measured clearance or professional medical assessment.
A CrCl above roughly 90 mL/min is generally considered normal kidney function. Values between 60 and 89 mL/min suggest mildly reduced function, 30 to 59 mL/min moderate reduction, 15 to 29 mL/min severe reduction, and below 15 mL/min kidney failure. These ranges broadly mirror the KDIGO GFR categories (G1 to G5), though CrCl and GFR are not identical measures and results should always be interpreted alongside the patient's clinical context.
The Cockcroft-Gault equation uses body weight directly, so CrCl rises with higher weight and falls with lower weight for the same age, sex, and creatinine value. In patients who are obese or underweight, many clinicians use an adjusted or ideal body weight instead of actual weight to avoid over- or under-estimating renal function. Unit mismatches are a common source of error too: this calculator expects weight in kilograms and serum creatinine in mg/dL, so values entered in pounds or micromol/L must be converted first, or the result will be inaccurate.
Want the clinical background? Learn how the Cockcroft-Gault formula works and why it matters for radiographers.
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