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Creatinine Clearance Calculator

Estimate your creatinine clearance with the Cockcroft-Gault formula. Used to assess kidney function and adjust medication dosing.

Enter age, weight, and serum creatinine to calculate your creatinine clearance.

Clearance (mL/min)Classification
≥ 90Normal
60 – 89Mildly decreased
30 – 59Moderately decreased
15 – 29Severely decreased
< 15Kidney failure

How it works

Cockcroft-Gault formula (Cockcroft & Gault, Nephron 1976): CrCl = ((140 − age) × weight in kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 for women. SI units are converted automatically (88.4 µmol/L = 1 mg/dL). The formula remains widely used for medication dose adjustment — modern estimates also use CKD-EPI 2021 (eGFR).

This calculation is an estimate, not a diagnosis. Cockcroft-Gault overestimates clearance in obesity and may be inaccurate at body composition extremes. Therapy and dosing decisions belong to your doctor or pharmacist.

Frequently Asked Questions

What is creatinine clearance?+
Creatinine clearance is a measure of how much blood the kidneys filter free of creatinine each minute. It serves as a surrogate marker for the glomerular filtration rate (GFR) and reflects kidney function.
How does the Cockcroft-Gault formula work?+
((140 − age) × weight in kg) / (72 × serum creatinine in mg/dL). For women, multiply the result by 0.85. Output is in mL/min. The formula has been in clinical use since 1976 and still drives many drug-dosing recommendations.
What values are considered normal?+
In healthy young adults, clearance is roughly 90–140 mL/min. It drops by about 1 mL/min per year with age. Sustained values below 60 mL/min for more than 3 months meet criteria for chronic kidney disease (CKD).
Cockcroft-Gault or CKD-EPI — which should I use?+
CKD-EPI 2021 is the recommended estimate of eGFR (e.g. KDIGO). Cockcroft-Gault gives the creatinine clearance — still required for many drug labels and older studies. The two complement each other; many clinicians compute both.
Why the 0.85 correction for women?+
Women on average have less muscle mass and therefore lower creatinine production. Without the correction, the formula would systematically overestimate clearance in women.
What does a value below 60 mL/min mean?+
Sustained < 60 mL/min for more than 3 months meets CKD stage G3 or worse. It warrants nephrology evaluation — common drivers are diabetes, hypertension, certain medications, or primary kidney disease.
Which factors distort the estimate?+
Obesity (overestimation), severe underweight, pregnancy, amputations, muscle wasting, vegan diets with low creatinine, and acute kidney injury can all skew the result. Confirm with 24-h urine collection or eGFR when in doubt.

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Creatinine Clearance Calculator Guide: Cockcroft-Gault Explained

8 min