How the creatinine clearance calculator works
The Cockcroft-Gault equation (1976) estimates how fast the kidneys clear creatinine, a waste product of muscle metabolism. Drug labels have long used it to set doses for kidney impairment.
× 0.85 for women
Which weight to use is debated. Actual body weight can overestimate clearance in obesity, so many pharmacists use ideal or adjusted body weight when actual weight is more than 20% to 30% above ideal. The function categories shown here roughly follow the KDIGO GFR stages, but CrCl and eGFR are not interchangeable.
Worked example
A 60-year-old man weighing 72 kg with a serum creatinine of 1.0 mg/dL has CrCl = 80 × 72 ÷ 72 = 80 mL/min, mildly reduced. A woman with the same values would be 80 × 0.85 = 68 mL/min.
For education only. Not medical advice; confirm with a qualified clinician.
Frequently asked questions
Is CrCl the same as eGFR?
No. Both estimate kidney function, but eGFR (CKD-EPI 2021) is normalised to body surface area and used for staging kidney disease, while Cockcroft-Gault CrCl is used for many drug dose adjustments.
What is a normal creatinine clearance?
Roughly 90 to 140 mL/min in healthy young adults, declining with age.
Which weight should I use?
Actual weight for normal-weight patients. For obesity, many references suggest adjusted body weight.
How do I convert µmol/L to mg/dL?
Divide by 88.4. A creatinine of 88 µmol/L is about 1.0 mg/dL.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.