Health tool
Creatinine Clearance Calculator
Estimate adult creatinine clearance with the Cockcroft-Gault equation using age, sex, body weight, and serum creatinine. This tool is useful for a quick kidney function estimate in mL/min, especially when reviewing adult renal dosing references or comparing lab values.
Result
Estimated Creatinine Clearance
Cockcroft-Gault
Creatinine clearance
85.86 mL/min
Using 80 kg and 1.1 mg/dL serum creatinine.
Weight Used
80 kg
Creatinine Used
1.1 mg/dL
Sex Factor
1.00
Formula
(140 - age) x kg x factor / (72 x SCr)
Details
Calculation Notes
mL/min
Guide
What Is This Calculator?
This creatinine clearance calculator estimates how much blood plasma the kidneys clear of creatinine each minute. It is based on the Cockcroft-Gault equation, a long-used adult CrCl formula that combines age, body weight, sex, and serum creatinine.
Creatinine clearance is commonly discussed when reviewing kidney function, renal dosing references, and whether a creatinine value should be interpreted in the context of age and body size. It should be treated as an estimate, not a diagnosis.
Method
How the Calculator Works
Formula
Cockcroft-Gault Equation
CrCl = ((140 - age) x weight kg x sex factor) / (72 x SCr)- CrCl: estimated creatinine clearance in mL/min.
- Age: adult age in years.
- Weight: body weight in kilograms.
- SCr: serum creatinine in mg/dL.
- Sex factor: 1.00 for male and 0.85 for female in this equation.
- Unit note: 1 mg/dL is commonly converted from about 88.4 umol/L.
Cockcroft-Gault estimates creatinine clearance, not body-surface-area-indexed eGFR. CKD-EPI and MDRD equations are different kidney function estimates and may be preferred for CKD staging or routine lab reporting.
Example
Worked Example
Example inputs: male, age 55 years, body weight 80 kg, serum creatinine 1.1 mg/dL.
- Substitute the values: ((140 - 55) x 80 x 1.00) / (72 x 1.1).
- Calculate the numerator: 85 x 80 x 1.00 = 6,800.
- Calculate the denominator: 72 x 1.1 = 79.2.
- Divide: 6,800 / 79.2 = 85.86 mL/min.
Use
How to Use the Calculator
- Select male or female as used by the Cockcroft-Gault equation.
- Enter adult age in years.
- Enter body weight and choose kg or lb.
- Enter serum creatinine from a blood test and choose mg/dL or umol/L.
- Read the estimated creatinine clearance and the converted values used.
Results
Understanding the Result
| CrCl range | General meaning | Important note |
|---|---|---|
| 90 mL/min or higher | Often compatible with preserved filtration. | Kidney health also depends on urine and clinical findings. |
| 60-89 mL/min | Mildly lower estimate in many adults. | Age, muscle mass, and body size matter. |
| 30-59 mL/min | Moderately reduced estimate. | Medication review and follow-up testing may be needed. |
| Below 30 mL/min | Severely reduced estimate. | Prompt clinical interpretation is important. |
Practical Notes
Benefits, Limitations, and Accuracy Tips
Mistakes
Common Mistakes to Avoid
- Mixing up mg/dL and umol/L creatinine units.
- Entering pounds while kg is selected, or kilograms while lb is selected.
- Using the result as a diagnosis without urine testing or clinical review.
- Assuming Cockcroft-Gault CrCl is identical to lab-reported eGFR.
- Using the equation for children, pregnancy, or unstable acute kidney injury.
- Ignoring medication-specific dosing instructions about weight selection.
FAQ
Frequently Asked Questions
What does this creatinine clearance calculator estimate?
It estimates adult creatinine clearance, often abbreviated CrCl, in mL/min using the Cockcroft-Gault equation.
What formula does the calculator use?
It uses CrCl = ((140 - age) x weight in kg x sex factor) / (72 x serum creatinine in mg/dL), with a sex factor of 0.85 for female and 1.00 for male.
Is creatinine clearance the same as eGFR?
No. Creatinine clearance is reported in mL/min and is not indexed to body surface area, while many eGFR results are reported as mL/min/1.73 m2.
Can this calculator be used for children?
No. The Cockcroft-Gault equation was developed for adults. Pediatric kidney function estimates usually use pediatric-specific equations and clinician review.
Why does the calculator ask for body weight?
The Cockcroft-Gault equation uses body weight as a proxy for creatinine production, which is related to muscle mass.
Which creatinine units can I enter?
You can enter serum creatinine in mg/dL or umol/L. The calculator converts umol/L to mg/dL before applying the equation.
What does a lower creatinine clearance mean?
A lower result can suggest reduced kidney filtration, but interpretation depends on medical history, lab trends, urine testing, medications, and clinical context.
Can creatinine clearance be used for medication dosing?
Many drug labels and dosing references use renal function estimates, but medication decisions should be made by a qualified clinician or pharmacist.
Does the result diagnose chronic kidney disease?
No. CKD diagnosis generally depends on persistent kidney abnormalities over time, often including eGFR and urine albumin results, not one calculator result alone.
Why is there a 0.85 factor for female sex?
The original Cockcroft-Gault equation applies a 0.85 multiplier for female patients to reflect lower average creatinine production in the study population.
When may this estimate be less reliable?
It may be less reliable during acute kidney injury, pregnancy, very high or low muscle mass, amputations, severe malnutrition, or extremes of body size.
Should I use actual, ideal, or adjusted body weight?
This calculator uses the body weight you enter. Clinical dosing references may specify actual, ideal, or adjusted weight depending on the medication and patient.
Why can serum creatinine look normal when clearance is low?
Serum creatinine is influenced by age, sex, muscle mass, and creatinine production, so a single creatinine number can miss reduced clearance in some adults.
Do I need a 24-hour urine collection?
This calculator does not require urine collection. Measured creatinine clearance from timed urine may be used when estimates are unreliable or more precision is needed.
More Tools
Related Calculators
Glossary
Key Terms
- Creatinine
- A waste product from muscle metabolism measured in blood and urine.
- Creatinine clearance
- An estimate of how quickly creatinine is cleared from blood, reported in mL/min.
- Serum creatinine
- The creatinine concentration measured in a blood sample.
- eGFR
- Estimated glomerular filtration rate, often indexed to 1.73 m2 body surface area.
- Cockcroft-Gault equation
- An adult formula that estimates CrCl from age, weight, sex, and serum creatinine.
- Renal dosing
- Adjusting medication selection or dose based on kidney function and drug labeling.
Sources
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
- Kidney Disease: Improving Global Outcomes (KDIGO). 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
- National Kidney Foundation. KDOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification.
- U.S. Food and Drug Administration. Pharmacokinetics in Patients with Impaired Renal Function: Study Design, Data Analysis, and Impact on Dosing.
Health & Medical Notice
Medical & Educational Disclaimer
This calculator is for general education only. It does not provide medical advice, diagnosis, treatment, medication dosing, or emergency guidance. Kidney function interpretation should be reviewed with a licensed healthcare professional who can consider your full medical history, lab trends, medications, and current condition.
Calculations and transformations execute locally on your machine with full offline support. Always verify critical results.
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