Creatinine Clearance (Cockcroft-Gault)
Use this tool to estimate creatinine clearance (CrCl) in mL/min from age, sex, body weight, and serum creatinine.
What is a creatinine clearance calculator?
A creatinine clearance calculator estimates how well your kidneys filter waste from the blood. In day-to-day clinical use, this estimate is often used to guide medication dosing, especially for drugs that are cleared by the kidneys.
The calculator above uses the Cockcroft-Gault equation, one of the most common formulas used in prescribing references:
CrCl (mL/min) = ((140 - age) × weight in kg) / (72 × serum creatinine in mg/dL)
For females, multiply the result by 0.85.
Why creatinine clearance matters
Creatinine is a waste product from muscle metabolism. Healthy kidneys filter creatinine from blood into urine. When filtration declines, creatinine levels in blood usually rise. Estimating clearance helps clinicians:
- Adjust doses for antibiotics, anticoagulants, and other renally cleared medications
- Monitor kidney function trends over time
- Support decisions around hydration, follow-up labs, and referrals
How to use this calculator correctly
1) Enter accurate lab and body data
Use your most recent serum creatinine value and confirm the unit. Small unit mistakes can produce large errors.
2) Use the right weight context
This simple version uses entered body weight directly. In some patients (for example, obesity or severe edema), clinicians may use ideal or adjusted body weight instead.
3) Treat output as an estimate
Creatinine clearance formulas are useful but imperfect. Use this as a support tool, not a stand-alone diagnosis.
Interpreting your result (general guide)
- 90 mL/min or higher: near-normal filtration in many adults
- 60–89 mL/min: mildly reduced range
- 30–59 mL/min: moderate reduction
- 15–29 mL/min: severe reduction
- Below 15 mL/min: kidney failure range
These bands are only rough clinical categories. Your doctor interprets results with symptoms, urinalysis, blood pressure, diabetes status, medication list, and repeat trends.
Limitations you should know
- Not validated for all pediatric use cases
- Can be inaccurate with rapidly changing kidney function (acute kidney injury)
- Less reliable in very low muscle mass, amputations, or unusual body composition
- Lab variability and hydration status can affect serum creatinine readings
Frequently asked questions
Is CrCl the same as eGFR?
Not exactly. They are related but calculated differently and used differently. Many labs report eGFR automatically, while many drug references still use Cockcroft-Gault CrCl for dosing.
Can I use this for medication changes on my own?
No. Always discuss medication decisions with a licensed healthcare professional.
How often should kidney function be checked?
It depends on your health profile. People with diabetes, hypertension, or known kidney disease usually need regular follow-up.
Medical disclaimer
This calculator is for educational use only and does not provide medical advice, diagnosis, or treatment. If your result is low or you feel unwell, seek care promptly.