01 · Overview
About this MME calculator & opioid conversion tool
Opioid conversions are one of the most error-prone calculations in hospital medicine. Converting between agents, routes, and formulations involves equianalgesic factors that are approximations at best — and getting them wrong in either direction means uncontrolled pain or respiratory depression.
This tool builds a complete inpatient opioid regimen rather than converting a single dose: it totals the 24-hour morphine milligram equivalents (MME) across scheduled and PRN agents, applies safety checks as the regimen grows, and helps structure basal, breakthrough, and multimodal components the way an inpatient pain plan is actually written.
02 · Core concept
What are morphine milligram equivalents (MME)?
MME expresses any opioid dose as the equivalent daily dose of oral morphine, so that different agents and routes can be summed into one number. It is the standard currency for opioid risk assessment: overdose risk rises measurably as the daily MME climbs, and the CDC's 2022 Clinical Practice Guideline asks prescribers to weigh benefits and risks with particular care as doses approach or exceed 50 MME/day.
Commonly used oral conversion factors: hydrocodone ×1, oxycodone ×1.5, oxymorphone ×3, hydromorphone ×4 (oral), codeine ×0.15, tramadol ×0.1, tapentadol ×0.4, and transdermal fentanyl ×2.4 per mcg/hour. These factors are population averages — individual pharmacokinetics, organ function, and drug interactions all move the real number.
03 · Exceptions
Why there is no valid 'buprenorphine MME'
Searches for a buprenorphine MME or morphine-equivalent conversion are common, and the honest answer is that no validated factor exists. Buprenorphine is a partial mu-opioid agonist with extremely high receptor affinity and a ceiling effect on respiratory depression — its dose-response curve simply does not map onto full agonists the way oxycodone maps onto morphine.
The CDC's 2022 guideline explicitly excludes buprenorphine from MME totals used for risk thresholds: a patient on buprenorphine for opioid use disorder or pain should not have those milligrams counted toward a 50 MME ceiling. When transitioning between buprenorphine and full agonists, use published induction and transition protocols (including low-dose 'micro-induction' approaches) rather than an equianalgesic table, and involve pain or addiction medicine when available.
04 · Rotation
Rotating opioids safely: cross-tolerance reduction
Tolerance to one opioid transfers only partially to another. When rotating agents in an opioid-tolerant patient, standard practice is to calculate the equianalgesic dose and then reduce it by 25–50%, titrating back up with breakthrough doses as needed. Skipping the reduction is a classic cause of iatrogenic overdose in the first 24–48 hours after a rotation.
Methadone deserves special respect: its conversion ratio is nonlinear and rises steeply with the pre-rotation MME (from roughly 4:1 at low doses to 12:1 or more at high doses), and its long, variable half-life causes delayed accumulation. Methadone conversions should follow dedicated protocols with specialist input, not a single multiplier.
05 · Built-in guardrails
Safety checks this tool applies
06 · Frequently asked questions
Frequently asked questions
How do I calculate total daily MME?
Multiply each opioid's total daily dose by its conversion factor, then sum across all agents. Example: oxycodone 10 mg every 6 hours is 40 mg/day × 1.5 = 60 MME. Add every scheduled and PRN opioid the patient actually receives. This calculator performs the totaling automatically as you build the regimen.
What is the MME conversion for buprenorphine?
There is no validated MME conversion for buprenorphine, and the CDC 2022 guideline explicitly excludes it from MME-based risk thresholds. As a partial agonist with a respiratory-depression ceiling and very high receptor affinity, buprenorphine does not behave like a scaled dose of morphine. Transitions on or off buprenorphine should follow dedicated protocols rather than an equianalgesic table.
Is 50 or 90 MME/day a hard limit?
No. The CDC's 2022 guideline moved away from the hard thresholds many readers took from the 2016 version. Overdose risk increases continuously with dose, so 50 MME/day is a point for heightened caution — reassessing benefit, avoiding concurrent benzodiazepines, and offering naloxone — not an automatic ceiling, and established patients should never be abruptly tapered to meet a number.
How much should I reduce the dose when switching opioids?
Reduce the calculated equianalgesic dose by 25–50% to account for incomplete cross-tolerance, then titrate with breakthrough doses. Use the larger reduction in elderly patients, renal or hepatic impairment, or when pain is currently well controlled.
How do I convert to a fentanyl patch?
Transdermal fentanyl at X mcg/hour corresponds to roughly 2.4·X MME/day (a 25 mcg/h patch ≈ 60 MME). Patches are only appropriate for opioid-tolerant patients with stable requirements — onset takes 12–24 hours and offset is equally slow, which makes them poor tools for acute titration.
Why is methadone conversion so different?
Methadone's equianalgesic ratio changes with the dose you are converting from — roughly 4:1 at low MME but 12:1 or higher above 300 MME — and its half-life (15–60 hours) far outlasts its analgesic duration, so it accumulates for days. Convert methadone only with a dedicated protocol and, ideally, specialist involvement.
Do these conversions replace clinical judgment?
No. Equianalgesic factors are population approximations. Age, kidney and liver function, drug interactions, opioid tolerance, and the clinical trajectory all change the safe answer. This tool is an educational aid for clinicians; verify every regimen against your institution's protocols before ordering.
07 · Sources
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.
- CDC. Calculating total daily dose of opioids for safer dosage (MME conversion reference).
- Fine PG, Portenoy RK. Establishing 'best practices' for opioid rotation: conclusions of an expert panel. J Pain Symptom Manage. 2009;38(3):418–425.
- McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. ASHP; 2018.
- Gudin J, Fudin J. A narrative pharmacological review of buprenorphine: a unique opioid for the treatment of chronic pain. Pain Ther. 2020;9(1):41–54.