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Pharmaceutical Calculators · Renal Dosing · PK / Clinical Trials

Creatinine Clearance Calculator

Estimate renal function using the Cockcroft-Gault equation for drug dose adjustment. Includes MDRD eGFR reference, IBW/ABW weight correction, CKD staging, and pharma trial context.

Quick Answer

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) in mL/min from age, sex, body weight, and serum creatinine. CrCl remains the default metric in many FDA drug labels and historical clinical trial protocols for renal dose adjustment, even though eGFR is preferred for CKD staging. This free calculator applies IBW/ABW weight correction for obese patients and reports MDRD eGFR as a reference value.

Cockcroft-Gault Formula (Primary — Drug Dosing)
CrCl = [(140 − Age) × Weightkg × F] / (72 × SCrmg/dL)
F = 1.0 (male)    F = 0.85 (female)    SCr = Serum Creatinine
MDRD eGFR = 175 × SCr−1.154 × Age−0.203 × (0.742 if female) × (1.212 if Black)

Enter Patient Values

Enter age, sex, weight, and serum creatinine. Optionally add height for IBW/ABW weight correction.

Patient demographics
Laboratory values
Height (optional — for IBW)
CrCl — Cockcroft-Gault
—
mL/min Primary (Dosing)
eGFR — MDRD
—
mL/min/1.73m² Reference (eGFR)
Weight Used
—
Dose Adjustment Note: Renal dosing adjustment may be required for medications with renal clearance at this CrCl level. Always verify with current prescribing information.

How to Use the Creatinine Clearance Calculator

1
Enter the patient's age in years (18–120). Cockcroft-Gault is validated for adult patients only.
2
Select sex — this applies the 0.85 female correction factor and the MDRD sex multiplier.
3
Enter body weight in kg or lbs and serum creatinine in mg/dL or μmol/L. Units are converted automatically.
4
Optionally enter height to enable IBW and ABW weight correction for overweight and obese patients.
5
Review CrCl (mL/min) for drug dosing, MDRD eGFR for reference, and compare against the specific label or protocol threshold.

Worked Example

Example Calculation

Patient: 65-year-old female, weight 70 kg, serum creatinine 1.2 mg/dL

Calculation: CrCl = [(140 − 65) × 70 × 0.85] / (72 × 1.2)

= [75 × 70 × 0.85] / 86.4 = 4462.5 / 86.4 = 51.7 mL/min

Interpretation: CrCl 51.7 mL/min — CKD Stage 3a (45–59 mL/min). Many antibiotics and metformin require dose review below CrCl 50 mL/min; verify the specific drug label.

Renal Dose Adjustment Thresholds

Common CrCl cutoffs referenced in drug labels and institutional protocols. Always verify the current prescribing information for each medication.

CrCl range CKD stage Typical dosing action Example drug classes
≥ 60 mL/min Stage 1–2 Standard dose in most labels Most renally cleared drugs at full dose
30–59 mL/min Stage 3 Dose reduction or interval extension Metformin, many β-lactams, gabapentin
15–29 mL/min Stage 4 Significant dose reduction; some contraindicated DOACs (apixaban, rivaroxaban), enoxaparin
< 15 mL/min Stage 5 Contraindicated or dialysis-specific dosing Metformin (contraindicated), aminoglycosides (extended intervals)

CKD Stage Classification

The following thresholds are used by this calculator for CKD staging based on eGFR/CrCl:

Stage 1: ≥ 90 — Normal Stage 2: 60–89 — Mildly Decreased Stage 3a: 45–59 — Mildly to Moderately Decreased Stage 3b: 30–44 — Moderately to Severely Decreased Stage 4: 15–29 — Severely Decreased Stage 5: < 15 — Kidney Failure

Renal Dosing Context for Pharma Professionals

Cockcroft-Gault CrCl remains embedded in FDA-approved drug labels, investigator brochures, and clinical trial protocols for renal dose adjustment. Phase 1 PK studies often stratify participants by CrCl bands; Phase 2/3 protocols specify inclusion/exclusion cutoffs and dose-modification rules tied to calculated CrCl at screening and on-treatment visits.

PK sampling schedules may shift when CrCl falls below protocol thresholds—for example, extended sampling windows for renally cleared drugs or triggered sparse PK at CrCl < 50 mL/min. Trial teams should document the weight type used (actual, IBW, or ABW) to match the label language. Compare CrCl with indexed eGFR using our GFR Calculator when protocols reference CKD-EPI, and apply dose calculations via our Dosage Calculator.

Aminoglycoside trials and hospital protocols frequently pair CrCl with therapeutic drug monitoring (peak/trough sampling). Sponsors should align the renal function metric in the statistical analysis plan with the metric specified in each drug's label—mixing CrCl and eGFR without conversion introduces dosing errors in both clinical practice and trial safety reporting.

About the Cockcroft-Gault Equation

The Cockcroft-Gault equation, developed in 1976, remains the standard formula for estimating creatinine clearance for drug dosing purposes. It uses age, sex, body weight, and serum creatinine as variables, reflecting the physiological relationship between muscle mass, creatinine production, and renal excretion.

The MDRD (Modification of Diet in Renal Disease) equation provides an estimated GFR normalized to body surface area (mL/min/1.73 m²), making it more useful for CKD staging and monitoring kidney disease progression. Unlike Cockcroft-Gault, MDRD does not require body weight and includes a race correction factor based on the original study population.

For obese patients, Adjusted Body Weight (ABW) is recommended for Cockcroft-Gault because adipose tissue contributes little to creatinine production. ABW = IBW + 0.4 × (Actual − IBW), where IBW is calculated using the Devine formula.

Sources and Further Reading

Frequently Asked Questions

Cockcroft-Gault estimates creatinine clearance (CrCl) in mL/min: CrCl = [(140 − Age) × Weight (kg) × F] / [72 × Serum Creatinine (mg/dL)], where F = 1.0 for males and 0.85 for females. Published by Cockcroft and Gault in 1976, it remains the most widely referenced equation in drug labels and prescribing information for renal dose adjustment.
Use actual body weight when it is at or below ideal body weight (IBW). Use IBW when actual weight is modestly above IBW (up to 1.3× IBW). Use adjusted body weight (ABW) when actual weight exceeds 1.3× IBW or BMI exceeds 30. This calculator automatically selects the appropriate weight when height is provided.
For obese patients, using actual body weight overestimates CrCl because adipose tissue contributes little to creatinine production. Adjusted Body Weight (ABW = IBW + 0.4 × [actual weight − IBW]) is the standard correction. IBW is calculated via the Devine formula from height and sex. Many institutional protocols and drug labels reference ABW for patients with BMI > 30.
Cockcroft-Gault was validated in adults aged 18–80. Performance may decline in very elderly patients (>80 years) and those with low muscle mass, malnutrition, or amputation. This calculator accepts ages 18–120 but results in extremes of age should be interpreted with clinical context. Pediatric dosing requires age-specific equations—not this adult tool.
For most renally cleared medications, use Cockcroft-Gault CrCl (mL/min) because FDA labels and historical trial protocols reference this metric. eGFR (mL/min/1.73 m²) from CKD-EPI or MDRD is preferred for CKD staging and nephrology monitoring but is not interchangeable with CrCl for dose adjustment. When a label specifies CrCl thresholds, do not substitute eGFR without protocol guidance.
In acute kidney injury (AKI), serum creatinine rises over hours to days and CrCl estimates may lag behind true GFR changes. Cockcroft-Gault assumes stable creatinine production and steady-state renal function. In CKD, creatinine is relatively stable and CrCl is more reliable for chronic dose adjustment. During AKI recovery or rapidly changing creatinine, use measured clearance, institutional protocols, or specialist guidance rather than a single CrCl snapshot.
Avoid relying on Cockcroft-Gault alone in patients with unstable or rapidly changing creatinine (AKI, post-contrast, rhabdomyolysis), extreme muscle mass (bodybuilders, amputees, malnutrition), pregnancy, or when creatinine is not at steady state. It is also unreliable in patients receiving dialysis or with non-creatinine-based clearance. Always integrate clinical context, urine output, and protocol-specific requirements.
No. Cockcroft-Gault is validated for adults only. Pediatric renal function requires age- and size-specific equations (e.g., Schwartz, updated bedside Schwartz, or measured iohexol/inulin clearance in trials). This tool is restricted to patients aged 18 and older. Pediatric dosing in clinical trials follows protocol-specified renal function criteria, not adult Cockcroft-Gault.
Many renally cleared drugs reference CrCl in their labels: aminoglycosides (gentamicin, tobramycin, amikacin) use CrCl for interval and dose selection; direct oral anticoagulants (apixaban, rivaroxaban) specify CrCl cutoffs; metformin, gabapentin, enoxaparin, and numerous antibiotics also require renal adjustment. Aminoglycoside protocols often target peak/trough levels with CrCl-driven dosing intervals—verify each drug's current prescribing information.
Report CrCl to one decimal place for calculation, then apply the rounding rule specified in the drug label or institutional protocol. Some labels use whole-number CrCl thresholds (e.g., <30, <50 mL/min); others specify exact cutoffs. When CrCl is near a threshold, confirm with the current prescribing information rather than assuming a single rounding convention across all medications.
Cockcroft-Gault CrCl is reported in absolute mL/min (not indexed to BSA). MDRD and CKD-EPI eGFR are normalized to 1.73 m² body surface area. For patients with very small or large body size, indexed eGFR and absolute CrCl can diverge meaningfully. Some PK analyses and trial protocols convert indexed eGFR to absolute mL/min using BSA. Use our BMI/BSA calculator when BSA-adjusted values are required.
MDCalc provides the standard Cockcroft-Gault calculation for clinical use. NovaPharmaNews adds pharma-specific context: IBW/ABW weight correction for obesity, MDRD eGFR reference, CKD staging, renal dose adjustment thresholds mapped to common drug classes, and trial-protocol framing (PK sampling windows, label CrCl cutoffs, links to GFR and dosage calculators). Designed for pharmacists, clinical pharmacology teams, and trial operations—not bedside quick reference alone.

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GFR GFR Calculator (CKD-EPI 2021) Rx Dosage Calculator BSA BMI / BSA Calculator t½ Half-Life Calculator FeNa FeNa Calculator (AKI)

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