MME Calculator
Convert opioid doses to morphine milligram equivalents (MME) for risk assessment. Enter medications, doses, and frequency to calculate total daily MME and understand risk thresholds.
Medical Disclaimer
This calculator is for educational purposes only. It does not provide medical advice and should not be used for prescribing decisions. Always consult a qualified healthcare provider.
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What Is Morphine Milligram Equivalent (MME)?
Morphine Milligram Equivalent (MME) is a standardized way to express opioid dosage across different medications. Because opioids vary in potency—oxycodone is roughly 1.5× stronger than morphine, hydromorphone is 4× stronger—comparing raw doses is misleading. MME converts everything to a morphine-equivalent scale, allowing meaningful comparison of total opioid burden.
The concept emerged from the opioid crisis as a tool for risk assessment. Research showed that overdose risk increases sharply above certain daily MME thresholds, regardless of which specific opioid a patient takes. The CDC adopted MME thresholds in their 2016 Guideline for Prescribing Opioids for Chronic Pain, and most state prescription drug monitoring programs (PDMPs) now track MME as a key risk indicator.
The Basic Formula
For example: 30 mg oxycodone/day × 1.5 = 45 MME/day. A patient taking this amount has an opioid burden equivalent to 45 mg of oral morphine daily.
MME is not meant to guide dose conversions when switching between opioids—that requires different calculations with safety margins for incomplete cross-tolerance. MME is specifically designed for cumulative risk assessment: when a patient takes multiple opioids or when comparing prescribing patterns across populations.
MME Conversion Factors by Drug
Each opioid has a specific conversion factor based on its potency relative to oral morphine. These factors come from pharmacological research and clinical consensus, though there is some variation between different published conversion tables.
| Opioid | Conversion Factor | Example: 30mg/day | Notes |
|---|---|---|---|
| Morphine (oral) | 1.0 | 30 MME | Reference standard |
| Oxycodone | 1.5 | 45 MME | Common Rx opioid |
| Hydrocodone | 1.0 | 30 MME | Similar to morphine |
| Hydromorphone | 4.0 | 120 MME | High potency |
| Codeine | 0.15 | 4.5 MME | Low potency |
| Tramadol | 0.1 | 3 MME | Weak opioid |
| Tapentadol | 0.4 | 12 MME | Dual mechanism |
| Methadone | 4-15* | Variable | Dose-dependent! |
| Fentanyl Patch | 2.4/mcg/hr | N/A | Special calculation |
⚠️ Special Cases: Methadone and Fentanyl
Methadone has a non-linear conversion—the factor increases with higher doses because of its unique pharmacokinetics and long half-life:
- • 1-20 mg/day: factor = 4
- • 21-40 mg/day: factor = 8
- • 41-60 mg/day: factor = 10
- • 61-80 mg/day: factor = 12
- • >80 mg/day: factor = 15
Fentanyl patches use a different formula: MME = mcg/hr × 2.4. A 25 mcg/hr patch = 60 MME/day. This accounts for continuous 72-hour transdermal delivery.
These factors are for oral administration unless otherwise noted. IV, IM, or other routes have different bioavailability and may require adjusted calculations.
MME Risk Thresholds: What the Numbers Mean
The CDC's 2016 guidelines established MME thresholds based on epidemiological data showing increased overdose risk at higher daily doses. These thresholds are guidelines, not absolute rules—clinical context always matters.
Most patients at this level can be managed with routine follow-up. Overdose risk exists but is relatively low. Standard precautions apply: avoid combining with benzodiazepines, assess for sleep apnea, monitor for signs of misuse.
Research shows overdose risk increases substantially above 50 MME/day. CDC recommends careful justification, enhanced monitoring (urine drug screens, PDMP checks), and discussing naloxone with patients. Consider specialist consultation for chronic use.
Overdose mortality increases significantly at this level. CDC guidelines recommend avoiding ≥90 MME/day unless benefits clearly outweigh risks. If already prescribed, consider tapering strategies. Mandatory naloxone prescribing in many states. Pain specialist consultation strongly recommended.
Important context: These thresholds were developed primarily for chronic non-cancer pain. Cancer pain, palliative care, and opioid use disorder treatment may appropriately exceed these levels. The thresholds identify statistical risk—individual patients with tolerance may be at lower risk at higher doses, while opioid-naive patients may be at significant risk even below 50 MME.
Clinical Scenarios: Calculating MME in Practice
Scenario 1: Post-Surgical Patient on Multiple Opioids
Calculating cumulative MME from combination therapy
A patient recovering from knee replacement is taking Oxycodone 10mg every 6 hours (4×/day) plus Morphine IR 15mg at bedtime for breakthrough pain.
MME Calculation:
Clinical Implications:
At 75 MME/day, this patient is in the "increased risk" category. For short-term post-operative use (days to 1-2 weeks), this may be appropriate with close monitoring. The prescriber should have a taper plan, avoid concurrent benzodiazepines, and consider naloxone education. Transition to non-opioid alternatives should begin as healing progresses.
Scenario 2: Chronic Pain Patient with Fentanyl Patch
Understanding high-MME therapy in established patients
A patient with chronic back pain has been stable on Fentanyl 50 mcg/hr patch (changed every 72 hours) plus Hydromorphone 4mg twice daily for breakthrough pain.
MME Calculation:
Clinical Implications:
At 152 MME/day, this patient is well above the high-risk threshold. However, for an established chronic pain patient with documented tolerance, sudden dose reduction would be inappropriate and potentially harmful. Management should involve: confirming medical necessity, pain specialist oversight, regular PDMP checks, naloxone prescription, and exploring multimodal alternatives. Any tapering should be gradual (10% reduction per month maximum).
Important Limitations of MME Calculations
MME is a useful screening tool, but it has significant limitations that users must understand to avoid misapplication.
🧬 Individual Variation
Opioid metabolism varies by genetics (CYP2D6 polymorphisms), age, liver function, and kidney function. The same MME can produce vastly different effects in different patients.
⏱️ Tolerance Effects
Patients on chronic opioid therapy develop tolerance. A patient stable on 100 MME/day for years has a different risk profile than an opioid-naive patient receiving the same dose.
💊 Route Matters
These factors assume oral dosing. IV administration has higher bioavailability. Transdermal, buccal, and intranasal routes each have different absorption profiles.
⚠️ Not for Dose Conversion
MME tables should NOT be used to convert between opioids when changing medications. Equianalgesic dose conversion requires different calculations with safety reductions.
🚫 What MME Cannot Tell You
- • Whether a specific patient will overdose
- • The appropriate dose for any individual
- • Whether current therapy is effective for pain control
- • How to safely taper or convert medications
- • Risk from concurrent substance use (benzodiazepines, alcohol)
Frequently Asked Questions
What is MME and why does it matter?
MME (Morphine Milligram Equivalent) standardizes opioid potency for comparison. CDC guidelines flag ≥50 MME/day for increased overdose risk and ≥90 MME/day for high risk. It helps clinicians assess cumulative opioid burden.
How accurate are MME conversions?
MME conversions are approximations, not exact equivalencies. Individual factors (tolerance, metabolism, route) affect actual potency. Methadone and fentanyl conversions are particularly variable. Use for risk screening, not dose titration.
Why is methadone conversion different?
Methadone has a long, variable half-life and non-linear dose-response. Higher doses have disproportionately greater MME values (e.g., 20mg = 4×, 60mg = 10×). This makes methadone conversion especially complex and dangerous to estimate.
Can I use this to adjust prescriptions?
No. This calculator is for educational risk assessment only. Opioid prescribing decisions require clinical evaluation, patient history, and professional judgment. Never change medications based solely on MME calculations.
📚 Sources & References
- CDC Clinical Practice Guideline for Prescribing Opioids (2022) - Current CDC recommendations
- CDC MME Conversion Factors - Official conversion table
- CMS Opioid MME Conversion Factors - Medicare/Medicaid reference