Creatinine Clearance Calculator
Estimate kidney function with the Cockcroft-Gault formula.
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
Creatinine clearance estimates how well the kidneys are filtering waste from the blood, and this calculator uses the long-established Cockcroft-Gault equation to produce that estimate from four simple inputs: age, body weight, serum creatinine, and sex. Creatinine is a waste product of normal muscle metabolism that healthy kidneys remove at a steady rate, so its concentration in the blood rises when kidney function declines. The equation combines the serum creatinine with age and weight, which act as a proxy for how much creatinine the body produces, and applies a correction factor for women, who typically have lower muscle mass. The result, expressed in millilitres per minute, approximates the glomerular filtration rate and is widely used to gauge kidney health and, importantly, to adjust the doses of medications that the kidneys clear, since impaired filtration can cause drugs to accumulate to dangerous levels. Clinicians rely on it constantly for safe prescribing, and it also helps stage chronic kidney disease. This tool provides an educational estimate only and is not a substitute for laboratory testing or professional medical judgement; dosing and diagnosis must be made by a qualified clinician. Enter the four values, using recent serum creatinine, to obtain the estimate.
CrCl = ((140 − age) × weight) / (72 × Scr), × 0.85 if female
The Cockcroft-Gault equation estimates creatinine clearance, a proxy for the kidney's filtration rate, from age, body weight, and the serum creatinine level. It multiplies 140 minus the age by the weight in kilograms, divides by 72 times the serum creatinine in mg/dL, and multiplies the result by 0.85 for women to account for their generally lower muscle mass. A higher serum creatinine or older age lowers the estimated clearance.
Source:Cockcroft-Gault equation (Cockcroft & Gault, 1976)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter age, weight, serum creatinine and sex.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Creatinine clearance updates instantly as you type — no button to press.
Frequently asked questions
What is creatinine clearance?
Creatinine clearance estimates the rate at which the kidneys remove creatinine, a muscle waste product, from the blood. It serves as a practical proxy for the glomerular filtration rate, the key measure of kidney function. Expressed in millilitres per minute, it tells clinicians how effectively the kidneys are filtering and whether kidney function is normal, mildly reduced, or significantly impaired.
What is the Cockcroft-Gault equation?
The Cockcroft-Gault equation is a formula published in 1976 that estimates creatinine clearance from a person's age, weight, serum creatinine, and sex. It remains widely used, especially for adjusting medication doses, because it is simple and only needs routinely available data. Newer equations like CKD-EPI estimate filtration differently, but Cockcroft-Gault is still standard in many drug-dosing guidelines.
Why does sex affect the result?
The equation multiplies the result by 0.85 for women because, on average, women have less muscle mass than men of the same age and weight, and therefore produce less creatinine. Without this adjustment, the formula would overestimate a woman's clearance. Selecting the correct sex ensures the estimate reflects typical differences in creatinine production between men and women.
What is a normal creatinine clearance?
A normal creatinine clearance for a healthy adult is roughly 90 to 120 millilitres per minute, though it declines gradually with age. Values below 60 sustained over time may indicate chronic kidney disease, and lower values indicate more severe impairment. Interpretation depends on the individual and clinical context, so any concerning result should be reviewed by a healthcare professional.
Why is creatinine clearance used for drug dosing?
Many medications are cleared from the body mainly by the kidneys, so when kidney function is reduced these drugs can build up and cause harm. Estimating creatinine clearance lets clinicians lower doses or lengthen dosing intervals for such drugs to keep them safe and effective. This is a major reason the Cockcroft-Gault estimate remains important in everyday clinical practice.