Antipsychotic dose equivalents may be utilized when switching between antipsychotics or when comparing different medications. Multiple methods are used to calculate antipsychotic dose equivalences, each with their own strengths and limitations. Variation in receptor binding profiles of newer agents, changes to methodology in clinical trials over the decades, and lack of dose response data for older agents means no one method will apply to all available agents. Furthermore, none of the available methods take into account a patient’s acuity status, specific physical and medical condition(s), or history of previous antipsychotic exposure. Equivalent doses are difficult to determine and often incorrect; therefore, the information below should be paired with caution and clinical judgement. Methods which currently exist focus on schizophrenia or psychosis dosing and may not accurately translate to other psychiatric diagnoses. It should also be noted that dose equivalency guidance may not predict individual patient efficacy or tolerability. An awareness and comparison of multiple methods is required for clinical decision making, and has been included in the table and references below. The link to the multi-method dose equivalent calculator referenced in Leucht et al. (2020) has also been included to aid in calculation of medications or formulations not included in the table below.
How should I convert doses between different antipsychotics?1-6
Oral Antipsychotic Dose Equivalents (based on olanzapine)
| Generic | Brand | DDD1,2 | ED953 | MED4 | CMD5 | |
|---|---|---|---|---|---|---|
| First Generation Antipsychotics | ||||||
| Chlorpromazine | Thorazine© | 30mg | N.A | N.A | 38.9mg | |
| Fluphenazine | Prolixin© | 1mg | N.A | N.A | 0.5mg | |
| Haloperidol | Haldol© | 0.8mg | 0.42mg | 0.53mg | 0.6mg | |
| Loxapine | Loxitane© | 10mg | N.A | N.A | N.A | |
| Perphenazine | Trilafon© | 3mg | N.A | N.A | 3.5mg | |
| Pimozide | Orap© | 0.4mg | N.A | N.A | N.A | |
| Thioridazine | Mellaril© | 30mg | N.A | N.A | 37.1mg | |
| Thiothixene | Navane© | 3mg | N.A | N.A | 2.0mg | |
| Trifluoperazine | Stelazine© | 2mg | N.A | N.A | 1.1mg | |
| Second Generation Antipsychotics | ||||||
| Aripiprazole | Abilify© | 1.5mg | 0.76mg | 1.33mg | 1.41mg | |
| Asenapine | Saphris© | 2mg | 0.99mg | 1.33mg | 0.89mg | |
| Brexpiprazole | Rexulti© | N.A | 0.22mg | N.A | N.A | |
| Cariprazine | Vraylar© | N.A | 0.5mg | N.A | N.A | |
| Clozapine | Clozaril© | 30mg | N.A | 40mg | 30.62mg | |
| Iloperidone | Fanapt© | N.A | 1.33mg | 1.07mg | N.A | |
| Lurasidone | Latuda© | 6mg | 9.69mg | 5.33mg | N.A | |
| Lumateperone | Caplyta© | N.A | N.A | N.A | N.A | |
| Olanzapine | Zyprexa© | 1mg | 1mga | 1mg | 1mg | |
| Paliperidone | Invega© | 0.6mg | 0.88mg | 0.40mg | N.A | |
| Quetiapine | Seroquel© | 40mg | 31.78mg | 20mg | 32.27mg | |
| Risperidone | Risperdal© | 0.5mg | 0.41mg | 0.27mg | 0.38mg | |
| Ziprasidone | Geodon© | 8mg | 12.29mg | 5.33mg | 7.92mg | |
Abbreviations: ED95 = 95% Effective Dose; OLZ = olanzapine; MED = Minimum Effective Dose; DDD = Defined Daily Dose; CMD = Classical Mean Dose; ICSAD = International Consensus Study of Antipsychotic Dosing, CPZ = chlorpromazine; n.a = not available.
a ED95 equivalence based off dose-response for predominant positive symptoms
Definitions:
Defined Daily Dose: assumed average maintenance dose per day for a drug used for its main indication for adults2
95% Effective Dose: the mean dose that produces 95% of maximum symptom reduction3
Minimum Effect Dose: the lowest fixed dose consistently more efficacious than placebo4
Classical Mean Dose: calculates mean doses utilized in randomized, double-blind, flexible dose available studies of antipsychotics5
Multi-method Dose Equivalent Calculator:3
Reviewer 1: Trisha McHugh, PharmD, BCPP
Reviewer 2: Roisin Sabol, PharmD
2025-2026 AAPP Resident and New Practitioner Committee
- WHO Collaborating Centre for Drug Statistics Methodology. (2024) ATC/DD Index 2024. Accessed July 14, 2025. [Weblink]
- Leucht, S., Samara, M., Heres, S., & Davis, J. M. (2016). Dose Equivalents for Antipsychotic Drugs: The DDD Method. Schizophrenia bulletin, 42 Suppl 1(Suppl 1), S90–S94. [Weblink]
- Leucht, S., Crippa, A., Siafis, S., Patel, M. X., Orsini, N., & Davis, J. M. (2020). Dose-Response Meta-Analysis of Antipsychotic Drugs for Acute Schizophrenia. Am J Psychiatry, 177(4), 342–353. [Weblink]
- Leucht, S., Samara, M., Heres, S., Patel, M. X., Woods, S. W., & Davis, J. M. (2014). Dose equivalents for second-generation antipsychotics: the minimum effective dose method. Schizophrenia bulletin, 40(2), 314–326. [Weblink]
- Leucht, S., Samara, M., Heres, S., Patel, M. X., Furukawa, T., Cipriani, A., Geddes, J., & Davis, J. M. (2015). Dose Equivalents for Second-Generation Antipsychotic Drugs: The Classical Mean Dose Method. Schizophrenia bulletin, 41(6), 1397–1402. [Weblink]
- Patel, M. X., Arista, I. A., Taylor, M., & Barnes, T. R. (2013). How to compare doses of different antipsychotics: a systematic review of methods. Schizophrenia research, 149(1-3), 141–148. [Weblink]