About MME (morphine milligram equivalents)
MME is a way of expressing the potency of different opioid medications on one common scale, using morphine as the reference point. Every opioid has a conversion factor relative to oral morphine; multiplying a medication's total daily dose in milligrams by its factor gives that medication's MME contribution. When a person takes more than one opioid, the individual MME values are added together to get a combined daily MME.
The standard formula
- MME per day (one medication) = total daily dose in mg × conversion factor for that opioid.
- Combined MME per day = sum of the MME values for every opioid taken that day.
- Transdermal fentanyl is dosed in micrograms per hour rather than milligrams; its factor (2.4) is applied directly to the mcg/hr strength.
- Methadone's factor rises with the daily dose because its relative potency increases at higher doses — this calculator uses the commonly cited tiered factors (4 up to 20 mg/day, 8 for 21-40 mg/day, 10 for 41-60 mg/day, 12 above 60 mg/day).
Putting the result in context
US CDC opioid prescribing guidance identifies 50 MME per day and 90 MME per day as commonly referenced thresholds: at or above 50, added caution and more frequent follow-up are typically recommended; at or above 90, clinicians are advised to avoid further increases or carefully justify them. These are population-level guideposts drawn from published guidance, not a personalized treatment plan.
When to consult a professional
This calculator performs the standard MME arithmetic for reference and does not provide dosing advice. Any change to an opioid prescription, taper, or treatment plan should be made with a licensed prescriber who knows the full clinical picture.