Creatinine Clearance Calculator
Calculate CrCl using the Cockcroft-Gault equation with actual, ideal, or adjusted body weight. Get instant CKD staging, drug dosing guidance, and clinical decision support for healthcare professionals.
Calqulate.net estimates kidney function from creatinine, age and weight using the Cockcroft-Gault equation, cross-checked with eGFR. You get accurate CKD staging and dosing guidance.
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What is Creatinine Clearance?
Creatinine clearance (CrCl) is the volume of blood plasma cleared of creatinine per unit time, measured in milliliters per minute (mL/min). It serves as a clinically practical estimate of the glomerular filtration rate (GFR)—the gold standard measure of kidney function.
Creatinine is a metabolic waste product generated from the normal breakdown of creatine phosphate in skeletal muscle. Production is relatively constant and proportional to muscle mass. Healthy kidneys filter creatinine from the blood into the urine at a predictable rate.
Normal Ranges
- Adult Males: 97-137 mL/min
- Adult Females: 88-128 mL/min
- Age Decline: ~1 mL/min/year after 40
Clinical Uses
- Drug dosing for renally cleared medications
- CKD staging and progression monitoring
- Pre-surgical kidney function assessment
Understanding the Variables:
(140 - Age): Accounts for age-related decline in kidney function. GFR decreases with age.
Weight (kg): Approximates muscle mass, which determines creatinine production. Most debated variable for obese patients.
72: A constant derived empirically to convert the equation's output to mL/min.
× 0.85: Adjustment factor for females, accounting for lower average muscle mass compared to males.
Developed in 1976 by Drs. Cockcroft and Gault using data from 249 male veterans with CrCl ranging from 30-130 mL/min.
Which Weight Should You Use?
Selecting the appropriate body weight is critical for accurate CrCl estimation. Here are evidence-based recommendations:
Normal Weight Patients
Use: Actual Body Weight (ABW)
When actual weight is within 20% of ideal body weight, ABW provides accurate estimation.
Underweight Patients
Use: Actual Body Weight (ABW)
For patients below their ideal body weight, always use actual weight. Using IBW would overestimate kidney function.
Overweight/Obese Patients (BMI ≥30 or >20% above IBW)
Use: Adjusted Body Weight with 40% Correction Factor
Multiple studies confirm the 40% correction factor provides the least bias and highest accuracy in obese patients.
Chronic Kidney Disease Staging (KDIGO 2012)
| Stage | GFR (mL/min) | Description | Clinical Action |
|---|---|---|---|
| G1 | ≥90 | Normal or High | Monitor if risk factors. No dose adjustment needed. |
| G2 | 60-89 | Mildly Decreased | Estimate progression. Some drugs may need monitoring. |
| G3a | 45-59 | Mild-Moderate Decrease | Evaluate complications. Adjust renally cleared drugs. |
| G3b | 30-44 | Moderate-Severe Decrease | Prepare for RRT. Significant dose adjustments. |
| G4 | 15-29 | Severely Decreased | Refer to nephrology. Major dose reductions. |
| G5 | <15 | Kidney Failure (ESRD) | Dialysis or transplant. Many drugs contraindicated. |
Note: G1 and G2 require additional evidence of kidney damage (albuminuria, structural abnormalities) to be classified as CKD.
Common Medications Requiring Renal Dose Adjustment
| Drug | Normal Dose | CrCl 30-59 | CrCl 15-29 | ESRD |
|---|---|---|---|---|
| Metformin | 500-2550 mg/day | Max 1000 mg/day if CrCl 30-45 | Contraindicated | Contraindicated |
| Gabapentin | 300-3600 mg/day | 200-700 mg BID | 100-300 mg daily | 125-350 mg post-HD |
| Lisinopril | 10-40 mg daily | Start 5 mg daily | Start 2.5 mg daily | Start 2.5 mg daily |
| Ciprofloxacin | 250-750 mg BID | 250-500 mg q12h | 250-500 mg q18h | 250-500 mg q24h post-HD |
| Enoxaparin | 1 mg/kg BID | Monitor anti-Xa | 1 mg/kg once daily | Consider UFH |
| Vancomycin | 15-20 mg/kg q8-12h | 15 mg/kg q24h | 15 mg/kg q48-72h | 15 mg/kg reload post-HD |
| Dabigatran | 150 mg BID | 75 mg BID with P-gp inhibitor | Not recommended | Contraindicated |
| Allopurinol | 100-800 mg daily | 100 mg daily | 100 mg every 2-3 days | 100 mg post-dialysis |
Disclaimer: This table provides general guidance only. Actual dosing should be based on current drug labeling, clinical guidelines, patient-specific factors, and therapeutic drug monitoring where applicable.
CrCl vs eGFR: Which Should You Use?
Healthcare professionals often face confusion about which equation to use for drug dosing:
✓ Use Cockcroft-Gault CrCl When:
- Drug labeling specifically requires CrCl
- Narrow therapeutic index drugs (vancomycin, aminoglycosides)
- DOACs (dabigatran, rivaroxaban)
- Elderly or obese patients
✓ eGFR is Acceptable When:
- Drugs with wide therapeutic indices
- Drug labeling allows eGFR
- CKD staging and monitoring
- Weight is not available
May Overestimate CrCl
- • Obese patients (using actual body weight)
- • Patients with edema or fluid overload
- • High protein diet consumers
- • Patients taking creatine supplements
May Underestimate CrCl
- • Elderly patients with muscle wasting (sarcopenia)
- • Amputees
- • Vegetarians or low protein diet
- • Patients with neuromuscular diseases
Why Our CrCl Calculator Is More Reliable
Who Uses This Calculator?
Physicians
Adjusting medication doses based on kidney function for patient safety.
Pharmacists
Verifying renal dosing before dispensing renally cleared medications.
Nurses
Monitoring kidney function and communicating with care team.
Scientific References
Who Built This Calculator?
This tool was developed by healthcare professionals and clinical pharmacists with expertise in nephrology and drug dosing. Our goal is to provide accurate, evidence-based tools that support clinical decision-making.
Need to calculate eGFR instead?
Try our CKD-EPI eGFR Calculator for kidney function assessment and CKD staging without requiring patient weight.
Kidney Health During GLP-1 Therapy
If you're taking a GLP-1 medication like semaglutide or tirzepatide and you've landed here checking your kidney numbers, here's the honest, calm version. For most people the main thing that connects these medications to kidney function is fairly simple, and it's something you can manage at home.
GLP-1 drugs can cause side effects like nausea, vomiting, and diarrhea, especially early on. When those symptoms are strong enough that you lose more fluid than you take in, you can get dehydrated. Dehydration is the main way kidney function tends to be affected, because your kidneys briefly get less blood flow to work with. It's usually temporary and improves once your fluids are back to normal. The medication itself is not typically damaging healthy kidneys directly, the fluid loss is the piece worth keeping an eye on.
Because of that, staying well hydrated is the easy, normal precaution that does most of the work. It matters most in the first few weeks after starting, and again for a little while after each dose increase, since that's when stomach side effects are most likely to show up. Sipping fluids through the day, and drinking a bit extra on any day you're queasy or your stomach is off, is usually plenty. If you ever can't keep fluids down for a stretch, that's the point to check in with your clinician rather than tough it out.
You may also see your clinician order a routine blood test to check renal function around the time you start or move up a dose. This is normal monitoring, not a sign something is wrong. It simply gives your care team a baseline and a quick way to confirm everything looks fine, and it's worth following their guidance on timing and any follow-up. If you want to understand when different side effects tend to appear and settle down, our GLP-1 side effect timeline walks through what to expect week by week, and you can revisit this creatinine clearance calculator any time you have a fresh lab result to plug in.
Wondering when side effects usually hit?
See a calm, week-by-week guide to what's common early on and when things typically settle.
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Frequently Asked Questions
Important Medical Disclaimer
This calculator is intended for educational and clinical decision support purposes only. It does not replace professional medical advice, diagnosis, or treatment. The Cockcroft-Gault equation may be less accurate in certain populations including the very elderly, morbidly obese, patients with muscle wasting diseases, amputees, and those with unstable kidney function. Always verify calculations and consult with a nephrologist, clinical pharmacist, or other qualified healthcare provider.
No data is stored. All calculations are performed locally in your browser. This tool is HIPAA compliant.
Tool Information
June 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.
About the authors
Meet Akabari
·Co-Founder, Calqulate.net