Antipsychotic Equivalent Dose Calculator

The Antipsychotic Equivalent Dose Calculator estimates chlorpromazine equivalence based on specific medication factors. This calculator helps clinicians and researchers compare antipsychotic potency and treatment intensity. Whether you're switching medications, assessing polypharmacy, or analyzing clinical data, this tool provides standardized clinical comparisons.

Select the antipsychotic medication to be converted.
Total daily dose in mg (mg/day).
Number of doses per day (validation only).

How Chlorpromazine Equivalent Is Calculated

The Chlorpromazine Equivalent (CPZ) is a standardized method used to compare the relative doses of different antipsychotic medications. It converts the prescribed milligram amount of a specific drug into the equivalent milligram amount of Chlorpromazine (the first-generation antipsychotic reference standard).

CPZ Equivalent = Daily Dose × Conversion Factor

Where:

  • Daily Dose: The total prescribed amount of the antipsychotic in mg.
  • Conversion Factor: The specific potency ratio relative to Chlorpromazine (e.g., Haloperidol is 100x more potent).

The process involves identifying the specific conversion factor for the selected drug, multiplying it by the daily dose, and rounding the result to one decimal place. These factors are derived from international consensus studies, such as Gardner et al., to ensure consistency across clinical practice.

What Your Chlorpromazine Equivalent Means

The calculated CPZ equivalent provides a standardized metric for assessing antipsychotic intensity. Clinicians use this number to ensure safe transitions between medications and to evaluate the total antipsychotic burden in patients taking multiple agents.

Clinical Interpretation

  • Low Dose (<300 mg CPZ): Often appropriate for maintenance therapy or initial treatment in sensitive populations.
  • Moderate Dose (300–600 mg CPZ): Typical therapeutic range for managing acute psychotic symptoms.
  • High Dose (>600 mg CPZ): Used for treatment-resistant conditions. Requires careful monitoring for side effects like extrapyramidal symptoms or metabolic changes.

Important Note

Individual patient response varies significantly based on metabolism, age, and specific condition. These equivalences are estimates and should not replace clinical judgment.

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →