MME Calculator
Enter one or two opioids with their total daily doses to calculate your combined morphine milligram equivalents (MME) per day. Conversion factors follow the CDC Clinical Practice Guideline for Prescribing Opioids for Pain (2022). The result is color-coded against the CDC caution thresholds of 50 MME/day and 90 MME/day. This tool covers 13 opioid formulations including methadone (with dose-dependent factors) and both fentanyl and buprenorphine transdermal patches.
What is an MME and why does it matter?
Morphine milligram equivalent (MME) is a standardized unit that converts any opioid dose into the amount of oral morphine that would produce an equivalent analgesic effect. Because different opioids vary enormously in potency (tramadol is about one-tenth as potent as morphine per milligram, while hydromorphone is four times as potent), clinicians and policymakers need a common currency to compare opioid loads across patients, prescriptions, and time. The CDC uses MME/day as the primary metric in its opioid prescribing guidelines. A total daily MME is calculated by multiplying each opioid dose by its conversion factor and summing across all opioids the patient takes concurrently.
CDC 2022 risk thresholds
The 2022 CDC Clinical Practice Guideline for Prescribing Opioids identifies two key dose thresholds based on overdose risk data. At 50 MME/day, the guideline advises caution: clinicians should increase monitoring frequency, discuss risks more explicitly, consider co-prescribing naloxone, and evaluate whether non-opioid or multimodal approaches could reduce the opioid load. At 90 MME/day, the risk of overdose death is substantially higher. The guideline recommends avoiding this threshold without a compelling clinical justification, a specialist consultation, and robust risk-mitigation measures such as urine drug testing and a treatment agreement. There is no completely safe opioid dose, so these thresholds are decision-support boundaries, not bright lines separating safe from unsafe.
Special cases: methadone, fentanyl patches, and buprenorphine
Three drug groups require extra care in MME conversion. Methadone has a long, unpredictable half-life and non-linear equianalgesic potency: the CDC uses a factor of 4 for daily doses up to 20 mg, rising to 8 for 21-40 mg, 10 for 41-60 mg, and 12 for doses above 60 mg/day. Fentanyl transdermal patches are dosed in micrograms per hour (mcg/hr), not milligrams per day; the CDC factor is 2.4 per mcg/hr, so a 25 mcg/hr patch equals 60 MME/day. Buprenorphine is a partial opioid agonist used both for pain (transdermal patch, sublingual film) and opioid use disorder treatment; the CDC assigns it a factor of 12.6 per mcg/hr for patches and 30 per mg for sublingual or buccal film, though its overdose risk profile differs from full agonists and interpretation requires clinical judgment.
Limitations and important notes
MME conversion factors are population averages based on equianalgesic studies. Individual responses to opioids vary due to genetics, tolerance, organ function, and drug interactions. Conversions are especially imprecise for methadone and buprenorphine. This calculator covers oral and transdermal routes only - intravenous, intramuscular, and epidural conversions require different factors and are not included. Combination products (such as oxycodone plus acetaminophen) should have only the opioid component entered. Children, patients with severe hepatic or renal impairment, and opioid-naive patients warrant additional caution beyond what any MME calculator can convey. This tool is for educational and informational purposes and does not substitute for clinical assessment by a qualified prescriber.
CDC 2022 opioid MME conversion factors
| Opioid | Dose unit | MME factor | Example: 10 units = ? MME |
|---|---|---|---|
| Codeine | mg/day | 0.15 | 1.5 MME |
| Fentanyl buccal/SL tablet | mcg/day | 0.13 | 1.3 MME |
| Fentanyl transdermal patch | mcg/hr | 2.4 | 24 MME |
| Hydrocodone | mg/day | 1.0 | 10 MME |
| Hydromorphone | mg/day | 4.0 | 40 MME |
| Methadone 1-20 mg/day | mg/day | 4 | 40 MME |
| Methadone 21-40 mg/day | mg/day | 8 | 80 MME (at 10 mg) |
| Methadone 41-60 mg/day | mg/day | 10 | 100 MME (at 10 mg) |
| Methadone >60 mg/day | mg/day | 12 | 120 MME (at 10 mg) |
| Morphine | mg/day | 1.0 | 10 MME |
| Oxycodone | mg/day | 1.5 | 15 MME |
| Oxymorphone | mg/day | 3.0 | 30 MME |
| Tapentadol | mg/day | 0.4 | 4 MME |
| Tramadol | mg/day | 0.1 | 1 MME |
| Buprenorphine SL/buccal film | mg/day | 30 | 300 MME |
| Buprenorphine transdermal patch | mcg/hr | 12.6 | 126 MME |
Oral morphine milligram equivalent factors from the CDC Clinical Practice Guideline for Prescribing Opioids for Pain (2022). Multiply the total daily dose by the factor to get MME/day. Fentanyl patch and buprenorphine patch are entered in mcg/hr.
Frequently asked questions
What does MME/day mean?
MME stands for morphine milligram equivalent. An MME/day figure tells you how many milligrams of oral morphine would be needed each day to produce an equivalent pain-relieving effect to the opioid regimen you entered. It is the standard unit used by the CDC and state prescription drug monitoring programs to compare opioid doses across different drugs and formulations.
Why does methadone have a variable conversion factor?
Methadone is unusual because its potency relative to morphine increases as the dose rises. At low doses (up to 20 mg/day) the CDC uses a factor of 4, meaning 10 mg/day of methadone equals 40 MME/day. At higher doses the factor rises to 8, 10, or 12. This non-linearity reflects methadone's complex pharmacology, including its very long and unpredictable half-life and NMDA receptor activity. Conversion to and from methadone should always involve a clinician experienced in its use.
How do I enter a fentanyl patch dose?
Fentanyl transdermal patches are labeled in micrograms per hour (mcg/hr), not milligrams per day. Enter the patch rate directly - for example, 25 for a 25 mcg/hr patch. The calculator multiplies this by 2.4 (the CDC 2022 factor) to give MME/day. A 25 mcg/hr patch equals 60 MME/day, which is already above the CDC caution threshold of 50 MME/day.
Is 90 MME/day always dangerous?
Not automatically, but it represents a meaningful risk inflection point. Research cited by the CDC found that patients prescribed 90 MME/day or more had significantly higher rates of opioid overdose than those prescribed lower doses. The guideline recommends that doses at or above this level be avoided or carefully justified, with specialist consultation, more frequent monitoring, naloxone co-prescription, and documented risk-benefit discussions. Risk also depends on the specific opioid, the patient's tolerance, organ function, and concurrent medications such as benzodiazepines.
Can I use this calculator for opioid-to-opioid rotation?
This calculator computes MME from a given dose, which is a starting point for rotation. However, the CDC and most guidelines caution that when rotating between opioids you should reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance. Rotating from or to methadone requires particular caution and specialist involvement. Always consult a clinical pharmacist or pain specialist when performing opioid rotation.
Does buprenorphine prescribed for opioid use disorder count toward MME?
Buprenorphine used for opioid use disorder (such as Suboxone) is treated differently in clinical guidelines. Because it is a partial agonist with a ceiling effect on respiratory depression, its overdose risk profile differs from full agonists. Some guidelines exclude buprenorphine from MME calculations when it is prescribed for opioid use disorder treatment. This calculator includes it because it is a valid analgesic and the CDC assigns it conversion factors, but interpret the result cautiously in the context of medication-assisted treatment.
What is naloxone and should I ask about it?
Naloxone (brand name Narcan) is an opioid antagonist that can rapidly reverse an opioid overdose. The CDC recommends that clinicians consider co-prescribing naloxone for patients receiving opioids at 50 MME/day or above, or for anyone with risk factors for overdose such as a history of substance use disorder, concurrent benzodiazepine use, or sleep-disordered breathing. Many US states now allow pharmacies to dispense naloxone without a separate prescription. Ask your prescriber or pharmacist about access.