Creatinine Clearance Calculator
Calculate estimated creatinine clearance (CrCl) via the Cockcroft-Gault equation for clinical pharmacokinetic assessment and renal drug dosing.
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Cockcroft-Gault applies a 0.85 factor for females to account for lower average muscle mass relative to body weight.
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Validated for adult patients aged 18 to 110. Cockcroft-Gault is not validated for pediatric patients.
yrs
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Blood test level of creatinine. Normal adult reference range is typically 0.6–1.3 mg/dL (53–115 µmol/L).
mg/dL
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Patient's current measured weight. Used to calculate Ideal and Adjusted Body Weights.
lbs
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Required to compute Ideal Body Weight (Devine formula) and Body Surface Area (Mosteller).
ft
in
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Guidelines recommend Actual weight if underweight/normal, and Adjusted weight (40% factor) if obese (>120% IBW).
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Some clinical protocols round low creatinine (e.g. <0.7 mg/dL) up in elderly/cachectic patients to prevent CrCl overestimation.
Recommended CrCl (Actual Weight)
83.16 mL/min
CrCl (Ideal Body Weight - Devine)
81.11 mL/min
CrCl (Adjusted Body Weight - 40%)
81.93 mL/min
BSA-Normalized CrCl (per 1.73 m²)
74.83 mL/min/1.73 m²
Patient Body Surface Area (BSA)
1.92 m²
Calculated Ideal Weight (IBW)
160.9 lbs (73.0 kg)
Weight Classification
102.5% of IBW (Normal Weight)
KDIGO Functional Staging
Stage 2 (Mild: 60–89 mL/min)
Clinical Dosing Guidance: Patient is at 102.5% of Ideal Body Weight (normal range). Actual body weight is recommended for standard renal drug dosing. Check drug-specific package inserts for narrow therapeutic index medications (e.g., aminoglycosides, vancomycin, DOACs).
Kidney Function Gauge (Cockcroft-Gault Dial)
STAGE 2: MILD REDUCTION
Substituted Cockcroft-Gault Equation:
Plugged-in:
Numerator:
Calculated Result: 83.16 mL/min (Normalized to 1.73 m²: 74.83 mL/min/1.73 m²).
CrCl = [ (140 − Age) × Weight (kg) ] ÷ [ 72 × Scr (mg/dL) ] × (0.85 if Female)Plugged-in:
[ (140 − 60) × 74.84 kg ] ÷ [ 72 × 1.00 mg/dL ] × 1.00Numerator:
80 × 74.84 = 5,987.42 | Denominator: 72 × 1.00 = 72.00Calculated Result: 83.16 mL/min (Normalized to 1.73 m²: 74.83 mL/min/1.73 m²).
* Results are estimates for educational and clinical guidance only and do not replace professional medical judgment. Cockcroft-Gault assumes stable renal function (steady-state creatinine) and is not validated for acute kidney injury (AKI) or pediatric patients (<18 years).
Clinical Renal Function Staging & Drug Dosing Implications
| KDIGO Stage | CrCl Range | Renal Function | Standard Drug Dosing Action |
|---|---|---|---|
| Stage 1 | ≥ 90 mL/min | Normal / Hyperfiltration | Standard 100% dosing. Monitor for drug accumulation if borderline. |
| Stage 2 | 60 – 89 mL/min | Mild Reduction | Generally normal dosing for most agents. Monitor nephrotoxic drugs closely. |
| Stage 3 | 30 – 59 mL/min | Moderate Impairment | Dose reduction or extended interval required for renally cleared drugs (e.g. DOACs, antibiotics). |
| Stage 4 | 15 – 29 mL/min | Severe Impairment | Substantial dose reductions (typically 25–50% of normal). Avoid NSAIDs and iodinated contrast. |
| Stage 5 | < 15 mL/min | Kidney Failure / ESRD | Dialysis dependency threshold. Implement strict renal failure protocols and post-HD supplemental dosing. |
About The Cockcroft-Gault Creatinine Clearance Calculator
The Cockcroft-Gault formula was published in 1976 by Donald W. Cockcroft and M. Henry Gault. Over four decades later, it remains the gold standard calculation referenced in FDA-approved medication package inserts and clinical pharmacokinetics for renal drug dosage adjustments.
While newer equations like CKD-EPI and MDRD estimate Glomerular Filtration Rate (eGFR) normalized to standard body surface area (1.73 m²) for chronic kidney disease (CKD) staging, the Cockcroft-Gault equation provides unindexed clearance (mL/min) reflecting a patient's absolute clearance capacity. For medications with narrow therapeutic windows (such as direct oral anticoagulants, aminoglycosides, digoxin, and vancomycin), Cockcroft-Gault CrCl remains the regulatory benchmark required for safe dosing.
Mathematical Equations & Illustrative Clinical Example
1. Cockcroft-Gault Clearance Equation:
For Males: CrCl (mL/min) = [ (140 − Age) × Weight (kg) ] ÷ [ 72 × Scr (mg/dL) ]
For Females: CrCl (mL/min) = [ (140 − Age) × Weight (kg) ] ÷ [ 72 × Scr (mg/dL) ] × 0.85
(If Serum Creatinine is measured in µmol/L: divide µmol/L by 88.4 to convert to mg/dL, or multiply numerator by 1.23 for males / 1.04 for females).
2. Ideal Body Weight (Devine Formula, 1974):
Male: IBW (kg) = 50.0 + 2.3 × (Height in inches − 60)
Female: IBW (kg) = 45.5 + 2.3 × (Height in inches − 60)
3. Adjusted Body Weight (AdjBW):
When Actual Body Weight (ABW) > 120% of IBW: AdjBW = IBW + 0.40 × (ABW − IBW)
4. Body Surface Area (Mosteller Formula):
BSA (m²) = √[ (Height in cm × Weight in kg) ÷ 3600 ]
Illustrative Worked Clinical Example:
A 60-year-old male presents with a Serum Creatinine of 1.00 mg/dL, height of 5'10" (70 inches = 177.8 cm), and weight of 165 lbs (74.84 kg):
- Ideal Weight:
IBW = 50 + 2.3 × (70 − 60) = 73.00 kg (160.9 lbs). - Weight Ratio:
74.84 kg ÷ 73.00 kg = 102.5%. Since patient is not obese (≤ 120% IBW), Actual Body Weight is used. - Cockcroft-Gault Calculation:
CrCl = [ (140 − 60) × 74.84 ] ÷ [ 72 × 1.00 ] = [ 80 × 74.84 ] ÷ 72 = 5987.42 ÷ 72 = 83.16 mL/min. - BSA Normalization: Patient's BSA is
1.92 m². Normalized CrCl is83.16 × (1.73 ÷ 1.92) = 74.83 mL/min/1.73 m². - Clinical Conclusion: The patient's clearance is 83.2 mL/min (Stage 2: Mild Reduction), qualifying for standard dosage on most medications.
How to Use This Calculator
- Select Measurement Unit: Choose US Customary (lbs, ft/in, mg/dL) or Metric / SI (kg, cm, µmol/L).
- Select Biological Sex: Toggle Male or Female. Female applies the 0.85 multiplier to reflect body composition differences.
- Input Clinical Parameters: Enter Patient Age (years), Serum Creatinine, Weight, and Height using either the numeric fields or responsive range sliders.
- Review Renal Staging: Inspect the signature blue result bar, the interactive semicircular gauge meter, and the breakdown table for Ideal vs. Actual weight clearance values.
Cockcroft-Gault Reference Chart Across Age & Weight ($S_{cr} = 1.0\text{ mg/dL}$, Male)
| Patient Age | Weight: 132 lbs (60 kg) | Weight: 165 lbs (75 kg) | Weight: 198 lbs (90 kg) | Weight: 231 lbs (105 kg) |
|---|---|---|---|---|
| 30 Years | 91.7 mL/min (Stage 1) | 114.6 mL/min (Stage 1) | 137.5 mL/min (Stage 1) | 160.4 mL/min (Stage 1) |
| 45 Years | 79.2 mL/min (Stage 2) | 99.0 mL/min (Stage 1) | 118.8 mL/min (Stage 1) | 138.5 mL/min (Stage 1) |
| 60 Years (Baseline) | 66.7 mL/min (Stage 2) | 83.3 mL/min (Stage 2) | 100.0 mL/min (Stage 1) | 116.7 mL/min (Stage 1) |
| 75 Years | 54.2 mL/min (Stage 3) | 67.7 mL/min (Stage 2) | 81.3 mL/min (Stage 2) | 94.8 mL/min (Stage 1) |
| 85 Years | 45.8 mL/min (Stage 3) | 57.3 mL/min (Stage 3) | 68.8 mL/min (Stage 2) | 80.2 mL/min (Stage 2) |
Important Clinical Pharmacokinetic Terms
Creatinine Clearance (CrCl)
Volume of blood plasma cleared of creatinine per unit of time (expressed in mL/min). Evaluates filtration capacity.
Serum Creatinine (Scr)
A chemical waste byproduct of muscle creatine phosphate metabolism, filtered freely by the glomerulus.
Ideal Body Weight (IBW)
Estimated lean body weight calculated from height. Prevents overestimating clearance in obese patients.
Adjusted Body Weight (AdjBW)
Incorporates a 40% correction factor for metabolically active lean tissue in patients with excess adipose tissue.
Frequently Asked Questions
Why does the FDA prefer Cockcroft-Gault over eGFR (CKD-EPI) for drug dosing?
Most landmark clinical trials that established medication dosage adjustments and safety parameters were conducted using the Cockcroft-Gault formula. Consequently, FDA drug package inserts specify dosage tiers in absolute mL/min via Cockcroft-Gault rather than indexed eGFR (mL/min/1.73 m²). Using eGFR without unindexing can lead to under-dosing in large individuals or over-dosing in petite individuals.
Which weight should be used in Cockcroft-Gault for obese patients?
For patients whose actual weight exceeds 120% of their Ideal Body Weight (IBW), clinical consensus and pharmacokinetic guidelines recommend using Adjusted Body Weight: AdjBW = IBW + 0.4 × (Actual Weight − IBW). Using actual body weight in obesity significantly overestimates renal clearance because fat tissue generates very little creatinine compared to muscle mass.
Can this calculator be used in Acute Kidney Injury (AKI)?
No. The Cockcroft-Gault equation strictly assumes steady-state renal function, where creatinine generation equals creatinine excretion. In acute kidney injury or rapidly changing renal function, serum creatinine lags behind acute changes in glomerular filtration rate, rendering Cockcroft-Gault estimates unreliable. Timed 24-hour urine collection or kinetic GFR formulas are required.
Why is serum creatinine sometimes rounded up in elderly or frail patients?
Elderly, bedridden, or severely malnourished patients frequently have diminished muscle mass, resulting in very low daily creatinine production. In these patients, a measured serum creatinine of 0.4 or 0.5 mg/dL does not indicate superior kidney function, but rather muscle wasting. To prevent excessive drug dosing, many clinical protocols round low creatinine up to 0.6–0.8 mg/dL.