Oral Morphine Equivalent Dose Calculator
Oral Morphine Equivalent Dose Calculator
Convert a 24-hour oral opioid dose to an oral morphine equivalent by four published factor sets at once, with the spread between them shown — because the published factors disagree by up to twofold on the same drug, and the figure is an arithmetic equivalence rather than a dose.
Oral morphine equivalent, by four published factor sets
4 sources, 7 opioidsOral hydromorphone, 8 mg over 24 hours — a 4 mg modified-release tablet twice a day
Four published factor sets, and where they disagree
Faculty of Pain Medicine: codeine 0.1, dihydrocodeine 0.1, tramadol 0.1, oxycodone 1.5, hydromorphone 5, tapentadol 0.4
CDC 2022: codeine 0.15, tramadol 0.2, oxycodone 1.5, hydromorphone 5, tapentadol 0.4
CDC pre-2022: codeine 0.15, tramadol 0.1, oxycodone 1.5, hydromorphone 4
Scottish Palliative Care Guidelines: codeine 0.1, dihydrocodeine 0.1, tramadol 0.1, oxycodone 2, hydromorphone 7.5
- what this figure is for
- putting a patient’s total opioid exposure on one scale, so that it can be compared with another patient’s, with a previous month’s, or with a study population’s. Every source that publishes a factor set built it for comparison or for surveillance
- what it is not for
- deciding what to take or what to use. CDC says it in its own words: “Do not use the calculated dose in MMEs to determine the doses to use when converting one opioid to another.” This page renders no dose and no target
- tramadol, 0.1 or 0.2
- a twofold disagreement on one of the most widely used opioids in the world. The Faculty of Pain Medicine, the Scottish Palliative Care Guidelines and CDC’s own pre-2022 file all use 0.1; CDC’s 2022 table uses 0.2. A patient on 400 mg of tramadol a day is on 40 or 80 mg of oral morphine equivalent depending only on which document you opened
- hydromorphone, 4 to 7.5
- CDC used 4 before 2022 and uses 5 now; the Faculty of Pain Medicine and the BNSSG chart use 5; the Scottish Palliative Care Guidelines divide oral morphine by 5 to 7.5 and their own worked example uses 7.5. That is a 1.875-fold spread, and it is in the direction that matters
- codeine, 0.1 or 0.15
- 0.1 in every United Kingdom source read here, 0.15 in both CDC sets. MSD’s equianalgesic table matches 200 mg of oral codeine to 30 mg of oral morphine, which is 0.15 as well
- oxycodone, 1.5 or 2
- 1.5 in the Faculty of Pain Medicine’s table, in the BNSSG chart and in both CDC sets; 2 in the Scottish Palliative Care Guidelines and in the Severn Hospice table. Converting 60 mg of morphine to oxycodone by one and back by the other does not return 60
- what no factor set contains
- the reduction for incomplete cross-tolerance. Every source that publishes factors also publishes a reduction to apply after them, between 25 and 50 per cent, and the factor tables themselves do not include it. The table below collects the six versions of that reduction
- the drugs this page refuses
- transdermal patches, because a rate in micrograms an hour is not a dose in milligrams a day; and methadone, because its ratio rises with the dose rather than being a constant. Both have pages of their own
Worked example
Oral hydromorphone, 8 mg over 24 hours — a 4 mg modified-release tablet twice a day
Faculty of Pain Medicine, factor 5: 8 × 5 = 40.00 mg of oral morphine a day
CDC 2022, factor 5: 8 × 5 = 40.00 — the two agree, now
CDC pre-2022, factor 4: 8 × 4 = 32.00. The same patient, the same day, 20 per cent less exposure on paper
Scottish Palliative Care Guidelines, dividing oral morphine by 7.5: 8 × 7.5 = 60.00
Highest ÷ lowest = 60.00 ÷ 32.00 = 1.88-fold on one unchanged prescription. All four numbers are correctly computed from a published factor
Switch the opioid to tramadol 400 mg a day and the spread is cleaner and larger: 40.00 by three sources and 80.00 by CDC's 2022 table, a 2.00-fold gap that happens to straddle the 50 MME a day figure CDC's own decision support fires at
Oral morphine itself returns the dose unchanged on all four — 60 mg a day is 60.00 — because every factor set is anchored on it. The disagreement only appears once the drug changes
The unit trap, in one line: a 50 micrograms an hour fentanyl patch is about 120 mg of oral morphine a day, not 50. Entering 50 in the dose field above with hydromorphone selected returns 250.00, which is wrong by a factor of two in one direction and by three orders of magnitude in the other
Published oral morphine equivalent factors, by source, and how far apart they are
| Opioid | Faculty of Pain Medicine | CDC 2022 guideline | CDC pre-2022 factors | Scottish Palliative Care Guidelines | Spread |
|---|---|---|---|---|---|
| Oral morphine | 1 | 1 | 1 | 1 | none |
| Oral codeine | 0.1 | 0.15 | 0.15 | 0.1 | 1.5x |
| Oral dihydrocodeine | 0.1 | not published | not published | 0.1 | none |
| Oral tramadol | 0.1 | 0.2 | 0.1 | 0.1 | 2x |
| Oral oxycodone | 1.5 | 1.5 | 1.5 | 2 | 1.33x |
| Oral hydromorphone | 5 | 5 | 4 | 7.5 | 1.88x |
| Oral tapentadol | 0.4 | 0.4 | not published | not published | none |
| Transdermal fentanyl, per microgram an hour | 2.4 | 2.4 | 2.4 | 30 to 60 mg a day matched to 12 micrograms an hour | 1x on the single factor; the manufacturer’s bands are 2.49x wide |
| Transdermal buprenorphine, per microgram an hour | 2.4 | not published | not published | 2.4 | no US figure exists at all |
| Oral methadone | varies | 4.7 | 4 to 12 by dose band | varies | 2.55x between CDC’s own two answers at 80 mg a day |
| Buccal, sublingual or lozenge fentanyl, per microgram | not published | not published | 0.13 | not published | single source only |
The reduction for incomplete cross-tolerance, by source
| Source | Reduction applied to the calculated equivalent | What else it says |
|---|---|---|
| Faculty of Pain Medicine, Opioids Aware | 25 to 50 per cent in most switches | At least 50 per cent above about 500 mg of oral morphine equivalent a day, in the elderly or frail, or where adverse effects are intolerable |
| Scottish Palliative Care Guidelines | Up to 30 per cent | “Consider reducing the dose by up to 30%” and re-titrate; reduce further if the patient is opioid toxic, frail or elderly |
| Severn Hospice conversion table | 25 to 30 per cent | 50 per cent when converting high doses, to avoid toxicity |
| MSD Manuals equianalgesic table | 50 per cent | 75 to 90 per cent for methadone, and the same reduction still applies on top of the dose-banded methadone ratios |
| Wellington ICU Drug Manual, Appendix 6 | 25 to 50 per cent | Calculate the equianalgesic figure first, then cut it |
| Fine and Portenoy, via Treillet et al. 2018 | 25 to 50 per cent, then a further 15 to 30 per cent either way | Explicitly excepts methadone and transdermal and transmucosal fentanyl from the first step |
One scale, four factor sets, and a twofold disagreement
An oral morphine equivalent puts every opioid a patient is taking onto one scale: each 24-hour dose is multiplied by a published potency factor relative to oral morphine, and the products are added. It is how opioid exposure is compared between patients, between months and between study populations, and it is the number that appears in prescribing audits, in surveillance data and in the thresholds that guidance is written around. Every document that publishes a factor set built it for that purpose.
The difficulty is that the published factors do not agree. Tramadol is 0.1 in the Faculty of Pain Medicine’s table, 0.1 in the Scottish Palliative Care Guidelines, 0.1 in CDC’s own pre-2022 conversion file and 0.2 in CDC’s 2022 guideline table: the same 400 mg a day is 40 mg of oral morphine equivalent or 80, and nothing about the patient has changed. Hydromorphone is 4, 5 or 7.5 depending on the document. Codeine is 0.1 on one side of the Atlantic and 0.15 on the other. Oxycodone is 1.5 in six of the sources read for this page and 2 in two of them. So this page prints four factor sets on every calculation and the ratio between the highest and the lowest, because an oral morphine equivalent figure means very little without the name of the document that produced it.
CDC’s disagreement with itself is worth dwelling on, because it is the cleanest demonstration available that these numbers are conventions rather than measurements. The 2022 guideline moved hydromorphone from 4 to 5, methadone from 3 to a flat 4.7, and tramadol from 0.1 to 0.2, and state Medicaid programmes reprogrammed their claims systems accordingly in 2023. No patient’s pharmacology changed on that date. What changed was the convention, and any audit that compares an exposure figure from before the change with one from after it is comparing two different quantities.
The other half of the problem is what the tables leave out. These are population approximations; the published cross-tolerance reduction applies after any equivalence; your own formulary governs. The notes below set all three out in full. And every one of the sources that publishes a factor set also publishes a reduction to apply after it — between 25 and 50 per cent, more in the frail and elderly, more again at high doses, and 75 to 90 per cent for methadone. The factor tables do not contain that reduction, which is why a calculator that stops at the arithmetic is the dangerous kind. The figure this page returns is an arithmetic equivalence and nothing else. It is not a dose, not a target and not a limit, and no part of this page says what any patient’s dose ought to be. Your own formulary, local conversion chart or specialist pain or palliative care service governs: where it differs from anything here, it wins. For the pharmacogenomic half of the problem — why a fixed factor for codeine or tramadol is wrong in both tails — see the CYP2D6 prodrug page and the CYP2D6 activity score interpreter.
Frequently asked questions
What is an oral morphine equivalent dose?
A single figure expressing a patient’s total opioid exposure on the oral morphine scale: each drug’s 24-hour dose is multiplied by a published potency factor relative to oral morphine and the products are added. It exists to compare exposure between patients, across time and against study populations. It is an arithmetic equivalence, not a dose.
Do the published factors agree?
No. Tramadol carries a factor of 0.1 in three of the four sources on this page and 0.2 in CDC’s 2022 table, a twofold gap. Hydromorphone is 4 in CDC’s pre-2022 file, 5 in CDC’s 2022 table and in the Faculty of Pain Medicine’s, and 7.5 in the Scottish Palliative Care Guidelines’ own worked example — 1.875 fold. Codeine is 0.1 in the United Kingdom and 0.15 in the United States. Oxycodone is 1.5 in most sources and 2 in two of them. An oral morphine equivalent is meaningless without naming the document.
Can I use this figure to change a patient from one opioid to another?
No, and CDC says so in its own words about its own numbers: “Do not use the calculated dose in MMEs to determine the doses to use when converting one opioid to another.” The factors are population averages from single-dose studies, they omit the reduction for incomplete cross-tolerance entirely, and they say nothing about the active metabolites, the receptor pharmacology or the half-life of the drug being moved to. This page renders no dose and no target.
Why does this page refuse to handle patches and methadone?
Because both would produce a plausible wrong answer. A patch is rated in micrograms an hour, which is not a milligram-a-day quantity: 50 micrograms an hour of fentanyl is about 120 mg of oral morphine a day, and treating the 50 as milligrams understates it by more than twofold. Methadone’s ratio rises with the dose — CDC’s own pre-2022 file uses 4, 8, 10 and 12 across four dose bands — so no single factor exists to multiply by. Both have their own pages, which print the bands with their sources.
What is the difference between an oral morphine equivalent and an MME?
In practice, the arithmetic is the same and the provenance is not. “Oral morphine equivalent” is the United Kingdom and palliative-care phrasing and rests on the Faculty of Pain Medicine’s and the BNF’s potency table; “morphine milligram equivalent” is the United States regulatory and epidemiological construct and rests on CDC’s factor table, which exists for population surveillance and policy. They use different factors for codeine, tramadol and hydromorphone, so the two figures for one patient differ. The MME page covers the construct and the criticism of it.
Related calculators
References
- Faculty of Pain Medicine of the Royal College of Anaesthetists. Opioids Aware: dose equivalents and changing opioids. Oral potencies, reviewed March 2023 against the BNF: codeine 0.1, dihydrocodeine 0.1, hydromorphone 5, morphine 1, oxycodone 1.5, tapentadol 0.4, tramadol 0.1, methadone “varies” with specialist advice required. Transdermal fentanyl 12, 25, 50, 75 and 100 micrograms an hour against 30, 60, 120, 180 and 240 mg of oral morphine a day. Conversion factors are an approximate guide only “because data are incomplete and individual variation is significant”; in most switches the calculated equivalent is cut by 25 to 50 per cent, and by at least 50 per cent above about 500 mg of oral morphine equivalent a day or in the elderly or frail; and “Opioid rotation is not recommended if a patient has responded to one opioid”.
- 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(RR-3). Its conversion table, reproduced in CDC’s own 2022 Implementation Guide, reads: codeine 0.15, transdermal fentanyl 2.4 per microgram an hour, hydrocodone 1, hydromorphone 5, methadone 4.7, morphine 1, oxycodone 1.5, oxymorphone 3, tapentadol 0.4, tramadol 0.2. Of its seven cautions, the second is “Equianalgesic dose conversions are only estimates”, the third “Do not use the calculated dose in MMEs to determine the doses to use when converting one opioid to another”, and the seventh “These conversion factors should not be applied to dosage decisions related to the management of opioid use disorder”.
- NHS Scotland. Scottish Palliative Care Guidelines: opioid/opiate conversion tables — switching between opioid medicines (Right Decision Service). Divisors on the 24-hour oral morphine dose: 2 subcutaneous morphine, 3 subcutaneous diamorphine, 2 oral oxycodone, 4 subcutaneous oxycodone, 5 to 7.5 oral hydromorphone, 10 subcutaneous hydromorphone, 30 subcutaneous alfentanil; codeine, dihydrocodeine and tramadol divided by 10. A seven-day buprenorphine patch at 5 micrograms an hour is matched to 12 mg of oral morphine a day. On switching: “Consider reducing the dose by up to 30%” and re-titrate, reducing further if the patient is opioid toxic, frail or elderly. Its oxycodone divisor of 2 is the figure that disagrees with the Faculty of Pain Medicine’s 1.5.
- MO HealthNet Division, Missouri Department of Social Services. Morphine Milligram Equivalent (MME) Factor Update for Hydromorphone, Methadone, and Tramadol, effective 17 September 2023, citing the CDC 2022 guideline. Records the three changes individually: hydromorphone 4 to 5, methadone 3 to 4.7, tramadol 0.1 to 0.2. The only document read for this batch that states the old and the new values side by side, which is what makes CDC’s disagreement with itself checkable rather than inferred.
- MSD Manuals Professional Version. Equianalgesic Doses of Opioid Analgesics. Parenteral against oral: morphine 10 to 30 mg, codeine 130 to 200, hydromorphone 1.5 to 7.5, methadone 10 to 20, oxycodone 15 to 20, oxymorphone 1 to 15. Its footnotes state that the equivalences come from single-dose studies and clinical experience and are approximations; that on changing opioid the equianalgesic dose is cut by 50 per cent, and by 75 to 90 per cent for methadone; and that the morphine-to-methadone ratio is non-linear, rising from about 2:1 below 30 mg of oral morphine equivalent a day to about 20:1 at 1000 mg a day and above. Its oral oxymorphone figure of 15 mg against 30 mg of morphine implies a potency of 2, where CDC publishes 3.
- Severn Hospice. Opioid Conversion Table, version 07.19. Oral potencies of 0.1 for codeine and dihydrocodeine but 0.15 for tramadol, and oral oxycodone reached by dividing oral morphine by 2 — two figures that disagree with the Faculty of Pain Medicine’s 0.1 and 1.5 for the same drugs. Transdermal fentanyl “approx. 100 to 150 times more potent than oral morphine” with the table built at 100:1; buprenorphine 5 micrograms an hour matched to 12 mg of oral morphine a day. Puts the switching reduction at 25 to 30 per cent, and at 50 per cent when converting high doses, to avoid toxicity.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/