How this instrument works
This calculator extends this site's MME instrument into a full opioid-to-opioid conversion. Every drug still carries the same CDC-published factor benchmarked against morphine — oxycodone 1.5, hydrocodone 1.0, hydromorphone 4.0, oxymorphone 3.0, codeine 0.15 — but instead of stopping at a single MME figure, the arithmetic runs a second step: that MME total is divided by the target drug's own factor to land on an equivalent daily dose in that drug's milligrams. MME is not the destination here, it is the common unit both drugs pass through on the way to a comparable number.
The factors themselves come from the CDC, published with its Clinical Practice Guideline for Prescribing Opioids for Pain and carried forward through the 2022 update largely unchanged from the original 2016 version. Because pharmacy systems, insurers, and prescription monitoring programs all reference the same table, a chart written in oxycodone milligrams and one written in hydromorphone milligrams become directly comparable the moment both pass through this shared scale, which is exactly why the intermediate MME step matters even when the final answer is expressed in a different drug entirely.
None of this makes a one-step dose switch safe on its own, and that limitation deserves to be stated as plainly as the arithmetic. These conversion factors are population averages built for surveillance and rough comparison, not an individualized prescription for any one patient. Real opioid rotation requires a qualified clinician, a deliberate reduction below the calculated equivalent — commonly 25 to 50 percent lower — to account for incomplete cross-tolerance between different opioids, and close monitoring afterward, because equianalgesic tables are approximations and a naive milligram-for-milligram switch carries genuine overdose risk.
- Enter the total daily dose in milligrams for the drug currently prescribed.
- Choose that drug in the Converting from menu.
- Choose the target drug in the Converting to menu.
- Read the MME/day subtotal and the resulting equivalent daily dose; the working block shows both steps.
Worked example — 30 mg/day oxycodone to hydrocodone
A patient takes 30 mg of oxycodone daily. Oxycodone's factor is 1.5, so 30 × 1.5 = 45 MME per day. Converting that MME total to hydrocodone, factor 1.0, gives 45 ÷ 1.0 = 45 mg per day — the equivalent daily dose in the second drug.
The same two steps handle a stronger drug just as easily: 8 mg per day of hydromorphone, factor 4.0, works out to 8 × 4.0 = 32 MME per day, which converts to oxycodone at 32 ÷ 1.5, about 21.3 mg per day. At the weaker end, 120 mg per day of codeine, factor 0.15, comes to only 120 × 0.15 = 18 MME per day, converting to oxymorphone, factor 3.0, at 18 ÷ 3.0 = 6 mg per day.
Questions
Can I use this to switch a patient directly from one opioid to another?
No, and this is the single most important limitation of the tool, repeated deliberately from the site's MME calculator because it matters just as much here. These conversion factors are population averages, not a safe recipe for a one-step switch in a real patient. Genuine opioid rotation needs a qualified clinician, an individualized dose reduction below the calculated figure — commonly 25 to 50 percent lower, to account for incomplete cross-tolerance between different opioids — and close monitoring afterward, because equianalgesic tables are approximate and a naive switch carries real overdose risk.
Why route the conversion through MME instead of comparing two drugs directly?
Because MME gives every opioid a common denominator. Rather than needing a separate ratio memorized for every possible pair among five or more drugs, one factor per drug against morphine is enough — multiply to reach MME, then divide by the target factor to land on that drug's equivalent dose. It's the same logic as converting two currencies through a shared reference rate rather than a direct exchange table for every pair.
What is incomplete cross-tolerance, and why does it matter here?
Tolerance built up to one opioid does not transfer completely to a different opioid, even at a calculated equal dose — receptor binding, metabolism, and individual genetics all vary between drugs. That gap means a patient switched to the mathematically equivalent dose of a new opioid can experience a stronger effect than expected, which is exactly why real rotations deliberately dose below the calculated equivalent rather than matching it exactly.
How much should the calculated dose typically be reduced in practice?
Clinical guidance commonly suggests starting 25 to 50 percent below the calculated equivalent dose when rotating opioids, then titrating upward based on the patient's response and monitoring. The exact reduction depends on the specific drugs involved, the patient's history, and clinical judgment — this calculator produces the starting reference point, not the final prescribed dose.
Where do the conversion factors used here come from?
From the CDC, first published alongside its 2016 opioid prescribing guideline and carried forward through the 2022 update (MMWR Recomm Rep. 2022;71(3):1-95). They were derived from pharmacologic potency data and expert consensus, benchmarked so that one milligram of oral morphine equals one MME.
Does a smaller output number mean the target drug is safer?
No — a smaller milligram figure simply reflects that the target drug is more potent per milligram, not that less total exposure is involved. Eight milligrams of hydromorphone and thirty milligrams of oxycodone can represent comparable risk despite the very different numbers, because the underlying MME total is what the comparison is actually built on.
References
- CDC Clinical Practice Guideline for Prescribing Opioids for Pain — United States, 2022 (MMWR Recomm Rep. 2022;71(3):1-95)
- CDC — Calculating Total Daily Dose of Opioids for Safer Dosage (conversion factor table)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.