Opioid conversion evidence, factors, and sources

Equianalgesic conversions are estimates, not dose recommendations. This page shows the current OpioidCalc factors, where the data came from, and where major clinical sources disagree.

conversion factors

medicine profiles

clinical sources

conversion references

For qualified healthcare professionals. Do not use an OME result as the dose of a replacement opioid. Confirm the medicine, route, formulation, units, and time period. Then account for incomplete cross-tolerance, organ function, age, comorbidities, concurrent medicines, prior exposure, and the patient's current clinical state. Seek specialist advice for methadone, high-risk conversions, or any uncertain result.

OpioidCalc conversion factors

These are the baseline factors used by OpioidCalc, checked on 1 September 2026. For each row, multiply the dose or delivery rate in the stated units by the factor to estimate mg oral morphine equivalent per day.

Current OpioidCalc opioid conversion factors
Medicine	Route	Input units	OME factor
Codeine	Oral	mg/day	0.1
Dihydrocodeine	Oral	mg/day	0.1
Hydrocodone	Oral	mg/day	1
Hydromorphone	Oral	mg/day	5
Methadone	Oral	mg/day	4.7
Morphine	Oral	mg/day	1
Oxycodone	Oral	mg/day	1.5
Oxymorphone	Oral	mg/day	3
Tapentadol	Oral	mg/day	0.33
Tilidine/Naloxone	Oral	mg/day	0.1
Tramadol	Oral	mg/day	0.2
Codeine	Parenteral	mg/day	0.25
Fentanyl	Parenteral	mcg/day	0.2
Hydromorphone	Parenteral	mg/day	15
Morphine	Parenteral	mg/day	3
Oxycodone	Parenteral	mg/day	3
Sufentanil	Parenteral	mcg/day	2
Oxycodone	Rectal	mg/day	1.5
Buprenorphine	Sublingual	mcg/day	0.04
Buprenorphine	Transdermal	mcg/hr	2.2
Fentanyl	Transdermal	mcg/hr	2.4

The reference library below records the calculator's general clinical basis. It does not assign one citation to each factor row. Published factors differ, as the comparison below shows.

Methadone needs special handling. OpioidCalc uses 4.7 when converting methadone to OME and a separate non-linear equation when converting OME to methadone. The table shows the factor applied by the calculator.

Clinicians can override eligible factors in the app to match an approved local reference. Oral morphine and methadone are not editable. A user override changes that device's result and does not change the baseline shown here.

Why a single "correct" table does not exist

Current authoritative sources publish different ratios because they use different populations, indications, routes, products, endpoints, and purposes. Some tables estimate exposure or utilisation. Others support palliative-care switching. The 2024 scoping review found low-quality evidence to support an opioid conversion guideline.

Selected differences in published factors, checked 1 September 2026
Medicine and route	OpioidCalc	ANZCA 2025	eviQ v2	CDC 2022
Codeine oral	0.1	0.13	0.125	0.15
Tapentadol oral	0.33	0.30	0.30	0.40
Buprenorphine transdermal	2.2	2	2	Not listed
Fentanyl transdermal	2.4	3	3.6	2.4
Oxycodone parenteral	3	3	2.5	Not listed

"Not listed" means the source does not publish that row in the cited table. It does not mean a factor of zero. Safer Care Victoria presents some conversions as ranges. Its 7-day buprenorphine patch guidance corresponds to roughly 1.8 to 2.4 mg oral morphine per day for each microgram/hour, illustrating why a midpoint such as 2.2 should still be treated as an estimate.

References used by the app

These are the conversion references cited by OpioidCalc. An earlier Metro South Health citation used an incomplete 2013 link. This page cites and links to the verified Queensland Health Version 6 PDF instead.

1.
Australian Medicines Handbook
Handbook
Australian Medicines Handbook Pty Ltd. Australian Medicines Handbook [Internet]. Adelaide, South Australia: Australian Medicines Handbook Pty Ltd.; c2022 [cited 2023 Feb 17]. Available from: https://amhonline.amh.net.au/
Open source
2.
The rediscovery of methadone for cancer pain management
research
Ayonrinde OT, Bridge DT. The rediscovery of methadone for cancer pain management. Med J Aust. 2000 Nov 20;173(10):536-40. doi: 10.5694/j.1326-5377.2000.tb139323.x. PMID: 11194738.
Open source
3.
eViQ Opioid Conversion Calculator
Calculator
Cancer Institute NSW. eViQ Opioid Conversion Calculator [Internet]. Sydney, New South Wales, Australia: Cancer Institute NSW; [updated 2021 Jan 7; cited 2023 Feb 17]. Available from: https://www.eviq.org.au/clinical-resources/eviq-calculators/3201-opioid-conversion-calculator
Open source
4.
CDC Clinical Practice Guideline for Prescribing Opioids for Pain
Guideline
Dowell D, Ragan KR, Jones CM, Baldwin GT, Chou R. CDC Clinical Practice Guideline for Prescribing Opioids for Pain — United States, 2022. MMWR Recomm Rep 2022;71(No. RR-3):1–95. DOI: http://dx.doi.org/10.15585/mmwr.rr7103a1
Open source
5.
ANZCA Opioid Dose Equivalence
Calculator
Faculty of Pain Medicine, ANZCA. Opioid Dose Equivalence.[Internet]. n.d. Available from: https://www.anzca.edu.au/getattachment/6892fb1 3-47fc-446b-a7a2-11cdfe1c9902/PM01-(Appendix-2)-Opioid-Dose-Equivalence-Calculat ion-of-Oral-Morphine-Equivalent-Daily-Dose-(OMEDD).aspx (accessed on 17 Feb 2023).
Open source
6.
Mathematical model for methadone conversion examined
Research
Fudin J, Marcoux MD, Fudin JA. Mathematical model for methadone conversion examined. Pract Pain Manag. 2012 Sep;12(7):46-51.
Open source
7.
Demystifying opioid conversion calculations
Handbook
McPherson ML. Demystifying opioid conversion calculations: a guide for effective dosing. Bethesda (MD): American Society of Health System Pharmacists; 2010.
Open source
8.
Metro South Health Opioid rotation and conversion learning package
Guideline
Metro South Palliative Care Service. Opioid Rotation Conversion Learning Package. Version 6. Metro South Health; 7 July 2020.
The earlier citation used an incomplete 2013 link. This page cites and links to the verified Queensland Health Version 6 PDF instead.
Open source
9.
A synthesis of oral morphine equivalents (OME) for opioid utilisation studies
Research
Nielsen S, Degenhardt L, Hoban B, Gisev N. A synthesis of oral morphine equivalents (OME) for opioid utilisation studies. Pharmacoepidemiol Drug Saf. 2016 Jun;25(6):733-7. doi: 10.1002/pds.3945. Epub 2015 Dec 22. PMID: 26693665.
Open source
10.
Safer Care Victoria Guidance on opioid conversion
Guideline
National Guidance Working Group. Guidance on opioid conversion. Melbourne (Australia): Safer Care Victoria; 2021 Feb. [cited 2023 Feb 17]. Available from: https://www.safercare.vic.gov.au/sites/default/files/20 21-02/GUIDANCE_Opioid%20Conversion%20FINAL_0.pdf
Open source
11.
Practical Pain Management Opioid dose calculator
Calculator
Practical Pain Management. Opioid dose calculator [Internet]. San Diego (CA): Practical Pain Management; c2021 [cited 2023 Feb 17]. Available from: https://opioidcalculator.practicalpainmanagement.com/
Open source
12.
Therapeutic Guidelines Limited Palliative care
Guideline
Therapeutic Guidelines Limited. Palliative care. In: eTG complete [Internet]. Melbourne (Australia): Therapeutic Guidelines Limited; c2021 [cited 2023 Feb 17].
Open source
13.
Switching from methadone to a different opioid
research
Walker PW, Palla S, Pei BL, Kaur G, Zhang K, Hanohano J, Munsell M, Bruera E. Switching from methadone to a different opioid: what is the equianalgesic dose ratio? J Palliat Med. 2008 Oct;11(8):1103-8. doi: 10.1089/jpm.2007.0285. PMID: 18980450; PMCID: PMC2982711.
Open source
14.
NHS England adult palliative-care opioid conversion table
Guideline
Greater Manchester and Eastern Cheshire Strategic Clinical Networks. Palliative Care Pain & Symptom Control Guidelines for Adults. NHS England; 2020. Table 42: dose conversions of weak opioids to oral morphine.
Open source
15.
AWMF S3 guideline for acute perioperative and post-traumatic pain
Guideline
Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin et al. S3-Leitlinie Behandlung akuter perioperativer und posttraumatischer Schmerzen. AWMF-Registernummer 001-025; 2022. Table 4.
Open source
16.
Tilidin-ratiopharm plus prolonged-release tablets product information
Product information
ratiopharm GmbH. Fachinformation Tilidin-ratiopharm plus Retardtabletten. Version 4; September 2020.
Open source
17.
NHS dihydrocodeine dosing and formulations
Clinical information
NHS. How and when to take dihydrocodeine. Page last reviewed 17 November 2022.
Open source
18.
Dihydrocodeine 60 mg prolonged-release tablets product information
Product information
Ennogen IP Ltd. Dihydrocodeine 60 mg prolonged-release tablets. Summary of Product Characteristics. Text revised 20 February 2025; last updated on emc 27 February 2025.
Open source
19.
German S3 palliative-care guideline, version 3.0
Guideline
Leitlinienprogramm Onkologie (Deutsche Krebsgesellschaft, Deutsche Krebshilfe, AWMF). S3-Leitlinie Palliativmedizin für Patient:innen mit einer nicht heilbaren Krebserkrankung. Long version 3.0; July 2026. Table 15.
Open source

Formulation-level medicine sources

Every pharmacology statement on the medicine pages links to one of these regulatory product-information documents, primary studies, or systematic reviews. The relevant source section and limitations appear with each statement.

Show all 44 clinical pharmacology sources

Review and currency

The conversion factors, references, and medicine details are reviewed together so this website and OpioidCalc remain consistent. Source revision and review dates appear beside each medicine statement.

Clinical information last checked 1 September 2026. Also read the Terms of Service.

Opioid conversion evidence, factors, and sources

OpioidCalc conversion factors

Why a single "correct" table does not exist

References used by the app

Australian Medicines Handbook

The rediscovery of methadone for cancer pain management

eViQ Opioid Conversion Calculator

CDC Clinical Practice Guideline for Prescribing Opioids for Pain

ANZCA Opioid Dose Equivalence

Mathematical model for methadone conversion examined

Demystifying opioid conversion calculations

Metro South Health Opioid rotation and conversion learning package

A synthesis of oral morphine equivalents (OME) for opioid utilisation studies

Safer Care Victoria Guidance on opioid conversion

Practical Pain Management Opioid dose calculator

Therapeutic Guidelines Limited Palliative care

Switching from methadone to a different opioid

NHS England adult palliative-care opioid conversion table

AWMF S3 guideline for acute perioperative and post-traumatic pain

Tilidin-ratiopharm plus prolonged-release tablets product information

NHS dihydrocodeine dosing and formulations

Dihydrocodeine 60 mg prolonged-release tablets product information

German S3 palliative-care guideline, version 3.0

Formulation-level medicine sources

Review and currency

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