Opioid Equivalence Calculator
Source-specific oral morphine equivalent estimates — not prescribing doses
Version 1.0.0
High-risk estimate only. Equianalgesic ratios are approximate, population-based and source-specific. Do not use the result as an automatic prescribing dose. Confirm the indication, formulation, route and local guidance; seek specialist advice for opioid switching.
Direction
Opioid and route
Opioid dose
Estimated oral morphine equivalent
—
mg/day
Safety limitations
- Equivalence does not establish equal safety or a recommended dose. Individual response varies with age, organ function, genetics, exposure, indication and formulation.
- The reverse calculation is retained to preserve the frozen legacy linked calculator behaviour. It is a mathematical inverse of the selected source-table factor, not a recommended opioid-switching dose. Incomplete cross-tolerance and other clinical adjustments are not applied.
- Methadone is excluded because conversion is non-linear and depends on prior exposure. Transmucosal fentanyl is excluded. Buprenorphine estimates are especially source-specific and weak; official morphine milligram equivalent tables often exclude it.
- Parenteral routes are grouped only to preserve the legacy table. Intravenous, intramuscular and subcutaneous administration are not necessarily interchangeable in every patient.
- Dextropropoxyphene and parenteral codeine are retained solely for legacy-table interpretation; availability and safety restrictions vary. Verify local policy.
No clinical values are intentionally saved by this control.
Equations
Opioid dose to oral morphine equivalent (OME)
OME (mg/day) = opioid dose in the displayed route-specific unit × factorFactors (mg OME per displayed unit): parenteral fentanyl 0.2 per microgram/day; parenteral sufentanil 2 per microgram/day; parenteral codeine 0.25, hydromorphone 15, morphine 3, oxycodone 3 and pethidine 0.4 per mg/day; oral codeine/dihydrocodeine 0.13, dextropropoxyphene 0.1, hydrocodone 1, hydromorphone 5, oxycodone 1.5, oxymorphone 3, tapentadol 0.4 and tramadol 0.2 per mg/day; sublingual buprenorphine 0.08 per microgram/day; transdermal buprenorphine and fentanyl 2.4 per microgram/hour; rectal oxycodone 1.5 per mg/day. These preserve the frozen legacy table and its source-specific choices; they are not a unified evidence table.
Oral morphine equivalent to selected opioid dose
Opioid dose in the displayed route-specific unit = OME (mg/day) ÷ factorThis is the exact mathematical inverse used by the calculator, not a recommended switching dose. No reduction for incomplete cross-tolerance is applied. Direct opioid-to-opioid conversion is deliberately unsupported. The frozen legacy calculator floors the master oral morphine equivalent to a whole number before inverse conversion, then floors calculated preparation-dose outputs using Math.floor; this two-stage quantisation is preserved. No tablet, patch or administration-device rounding is performed.
References
- 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(3):1-95. PMID: 36327391 DOI: 10.15585/mmwr.rr7103a1
- Faculty of Pain Medicine, Australian and New Zealand College of Anaesthetists. Opioid dose equivalence calculation table. PS01(PM) Appendix. Melbourne: ANZCA; 2021.
- Scottish Palliative Care Guidelines. Fentanyl patches. Edinburgh: Healthcare Improvement Scotland; updated 2025.
- Fine PG, Portenoy RK; Ad Hoc Expert Panel on Evidence Review and Guidelines for Opioid Rotation. Establishing best practices for opioid rotation: conclusions of an expert panel. J Pain Symptom Manage. 2009;38(3):418-425. PMID: 19735902 DOI: 10.1016/j.jpainsymman.2009.06.002
- Busse JW, Craigie S, Juurlink DN, Buckley DN, Wang L, Couban RJ, et al. Guideline for opioid therapy and chronic noncancer pain. CMAJ. 2017;189(18):E659-E666. PMID: 28483845 DOI: 10.1503/cmaj.170363