Vancomycin Dosing Calculator
Calculate vancomycin dosing based on patient weight, renal function (CrCl), and estimated pharmacokinetic parameters.
About this calculator
Vancomycin is renally cleared and has a narrow therapeutic window, so dosing is individualized to body weight and kidney function rather than given as a flat dose. This calculator first estimates creatinine clearance (CrCl) using the Cockcroft-Gault equation (Cockcroft & Gault, 1976): CrCl = [(140 - age) x weight x (0.85 if female)] / (72 x serum creatinine). The recommended dose applies the commonly-cited empiric range of 15-20 mg/kg (this calculator uses 15 mg/kg as a starting point) to the patient's ACTUAL body weight, consistent with the 2020 ASHP/IDSA/PIDS/SIDP consensus guideline on vancomycin dosing (Rybak et al.). This is a real point of difference from many other renally-cleared, weight-based drugs (including this site's aminoglycoside dosing calculator), where an obesity-adjusted dosing weight is standard -- Rybak 2020 specifically calls for actual body weight for vancomycin maintenance dosing, not an IBW-adjusted weight, even in obese patients. This calculator also computes an ideal body weight via the Devine formula for reference, but does not use it to set the dosing weight. Dosing interval is widened as CrCl falls, reflecting slower renal clearance.
Because actual-weight dosing can produce large per-dose and total daily amounts in larger patients, this calculator also flags when the total daily dose exceeds the 2020 guideline's empiric ceiling of 4,500 mg/day. The estimated trough uses a one-compartment pharmacokinetic model with an elimination rate constant commonly attributed to Matzke et al. (1986), scaled by the steady-state accumulation factor for repeated dosing (1/(1 - e^(-k x tau))) rather than a single dose's decay alone -- this is a rough estimate, not a substitute for an actual drawn level. The 2020 consensus guideline that supports the 15-20 mg/kg empiric dose recommends a 20-35 mg/kg loading dose in appropriate patients before starting maintenance dosing; this calculator does not model a loading dose, only the maintenance regimen, so factor that in separately when appropriate. The same guideline has also moved away from trough-only monitoring (historically targeted at 15-20 mg/L) toward AUC-guided dosing, targeting an AUC24/MIC ratio of 400-600, because trough-only monitoring is associated with higher nephrotoxicity risk for the same efficacy. This calculator estimates a trough, not an AUC, so treat its output as a starting-point estimate for clinical judgment and actual drawn levels -- never as a substitute for pharmacy or infectious-disease consultation on an individual patient's dosing and monitoring plan.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
This tool estimates a starting point only and is not a validated clinical decision-support system. It does not account for every patient-specific factor (organ function, drug interactions, allergies, comorbidities, or current clinical status). Any dose, rate, or setting must be independently verified by the treating clinician and pharmacist or respiratory therapist against current institutional protocols, product labeling, and the patient's full clinical picture before being administered or applied.
Inputs
Results
Recommended Dose
1,000 mg
Dosing Interval
8 hours
Exceeds 4,500 mg/day Guideline Ceiling
No
Estimated Trough
20.9 mcg/mL
Figures current as of 2020. Sources: Rybak MJ, Le J, Lodise TP, et al. Therapeutic monitoring of vancomycin for serious methicillin-resistant Staphylococcus aureus infections: a revised consensus guideline and review by the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists. Clin Infect Dis. 2020;71(6):1361-1364., Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
How to Use This Calculator
- Enter Actual Body Weight, Height, and Age.
- Set Serum Creatinine and select Female Patient.
- Review Recommended Dose (mg), Dosing Interval (hours), Total Daily Dose (mg/day), and the steady-state Estimated Trough (mcg/mL) as starting-point estimates, not a finalized order.
- Use Creatinine Clearance (CrCl) (mL/min) and Dosing Weight Used (kg, actual body weight per Rybak 2020) to understand how the dose was derived — Ideal Body Weight is shown for reference only.
- Check the Exceeds 4,500 mg/day Guideline Ceiling flag for larger patients, and remember a separate loading dose (20-35 mg/kg) may be indicated but isn't modeled here.
- Confirm dosing and monitoring (increasingly AUC-guided rather than trough-only) with pharmacy or infectious-disease consultation and actual drawn levels before treating a patient.
How the result changes with Actual Body Weight
| Actual Body Weight | Recommended Dose | Dosing Interval | Exceeds 4,500 mg/day Guideline Ceiling |
|---|---|---|---|
| 35 | 500 mg | 24 hours | No |
| 53 | 750 mg | 12 hours | No |
| 105 | 1,500 mg | 8 hours | No |
| 175 | 2,750 mg | 8 hours | Yes |
What each input means
- Actual Body Weight
- Patient's actual body weight in kilograms.
- Height
- Patient's height in centimeters (used for ideal body weight).
- Age
- Patient's age in years.
- Serum Creatinine
- Most recent serum creatinine level in mg/dL.
- Female Patient
- Adjusts the Cockcroft-Gault creatinine clearance calculation.
What each result means
- Total Daily Dose
- Recommended Dose × doses/day. The 2020 ASHP/IDSA/PIDS/SIDP guideline caps empiric total daily dosing at 4,500 mg/day.
- Exceeds 4,500 mg/day Guideline Ceiling
- True when Total Daily Dose is above the 2020 guideline's 4,500 mg/day empiric ceiling — most likely for larger patients now that dosing weight is actual body weight. Requires clinical review, not a dose to give as calculated.
- Estimated Trough
- Steady-state trough estimate (includes the multiple-dose accumulation factor, not just single-dose decay) — a rough estimate, not a substitute for an actual drawn level.
- Dosing Weight Used
- Actual body weight — per Rybak 2020, vancomycin maintenance dosing uses actual body weight, not an obesity-adjusted weight.
- Ideal Body Weight (reference only)
- Devine-formula IBW, shown for reference. Not used to set the dosing weight above — vancomycin dosing uses actual body weight per Rybak 2020.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersActual Body Weight = 70, Height = 170, Age = 40, Serum Creatinine = 1 = 5 input(s) provided
- Calculate Recommended DoseRecommended Dose1000 = 1000
- Calculate Dosing IntervalDosing Interval8 = 8
- Calculate Estimated TroughEstimated Trough20.9 = 20.9
- Calculate Creatinine ClearanceCreatinine Clearance97.2 = 97.2
- Calculate Dosing Weight UsedDosing Weight Used70 = 70
Figures and sources
- Vancomycin therapeutic monitoring consensus guideline (actual-weight dosing, AUC-guided monitoring) (2020) — Rybak MJ, Le J, Lodise TP, et al. Therapeutic monitoring of vancomycin for serious methicillin-resistant Staphylococcus aureus infections: a revised consensus guideline and review by the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the Society of Infectious Diseases Pharmacists. Clin Infect Dis. 2020;71(6):1361-1364.
- Cockcroft-Gault creatinine clearance equation (1976) — Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What formula does this calculator use to estimate kidney function?
It uses the Cockcroft-Gault equation (Cockcroft & Gault, 1976): creatinine clearance equals (140 minus age, in years) times weight in kg times 0.85 for female patients, divided by 72 times serum creatinine in mg/dL. It's one of several creatinine clearance estimates in clinical use and remains a standard choice for vancomycin dosing decisions.
Why does the calculator use a different weight for dosing than the patient's actual weight?
It doesn't -- this calculator's dosing weight IS the patient's actual body weight. That's a deliberate, guideline-driven choice, not an oversight: the 2020 ASHP/IDSA/PIDS/SIDP consensus guideline (Rybak et al.) specifically recommends actual body weight for vancomycin maintenance dosing, even in obese patients, unlike many other renally-cleared, weight-based drugs where an ideal-body-weight-adjusted dose is standard (this site's aminoglycoside dosing calculator, for example, does use an adjusted weight above 120% of ideal). This calculator also shows an ideal body weight (Devine formula) for reference, but it is informational only -- it is not used to set the dosing weight.
Is trough level still the recommended way to monitor vancomycin?
Not exclusively anymore. The 2020 ASHP/IDSA/PIDS/SIDP consensus guideline has moved toward AUC-guided monitoring (targeting an AUC24/MIC ratio of 400-600) as the preferred approach for serious infections, since it's associated with lower kidney injury risk than trough-only monitoring at the same efficacy. This calculator estimates a trough level using a simplified model, not an AUC.
Can I use this calculator's recommended dose without a level check?
No -- this calculator provides a starting-point estimate based on population pharmacokinetic formulas, not an individualized, level-verified dose. Vancomycin has a narrow therapeutic window where under-dosing risks treatment failure and over-dosing risks kidney injury and ototoxicity, so actual dosing and monitoring should always involve pharmacy or infectious-disease consultation and real drawn levels for the specific patient.
Does this calculator include a loading dose, and what happens for very large patients?
Neither is fully modeled, and both are flagged rather than silently ignored. The 2020 ASHP/IDSA/PIDS/SIDP guideline recommends a 20-35 mg/kg loading dose in appropriate patients before starting maintenance dosing, to reach therapeutic concentrations faster -- this calculator only computes the maintenance regimen, not a separate loading dose, so factor that in with pharmacy input when appropriate. Separately, because vancomycin maintenance dosing uses actual body weight (see the earlier question), larger patients can compute to a large total daily dose; the guideline caps empiric total daily dosing at 4,500 mg/day, and this calculator flags (Exceeds 4,500 mg/day Guideline Ceiling) when the computed total crosses that line, so it's visible rather than silently applied.
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