How this opioid conversion calculator works
This tool estimates an equianalgesic daily dose by converting your current opioid regimen to a common reference point: morphine milligram equivalents (MME). Once MME is estimated, it converts that total to the chosen target opioid.
The formula is straightforward:
- Total current daily dose (mg) = dose per administration × administrations per day
- MME/day = total daily dose × opioid conversion factor
- Target opioid daily dose (mg) = MME/day ÷ target conversion factor
Opioid conversion factors used in this calculator
The calculator uses commonly referenced oral MME factors for education:
- Morphine: 1.0
- Oxycodone: 1.5
- Hydrocodone: 1.0
- Hydromorphone: 4.0
- Oxymorphone: 3.0
- Codeine: 0.15
- Tramadol: 0.1
- Tapentadol: 0.4
These numbers are approximate and may vary by source, route, individual patient response, organ function, and clinical setting.
Why cross-tolerance reduction matters
When switching from one opioid to another, patients often have incomplete cross-tolerance. A mathematically equivalent dose can still be too high. That is why many clinicians start below the calculated equivalent dose (often 25% to 50% lower), then titrate based on pain control and side effects.
This page lets you apply that reduction directly so you can see both the theoretical equivalent and a more cautious starting estimate.
Practical interpretation of results
1) Look at total MME/day first
MME/day is a broad risk marker, not a complete clinical decision rule. Higher daily MME is associated with higher risk of respiratory depression and overdose.
2) Then review target mg/day and mg per dose
The calculator provides an estimated target daily dose and estimated amount per administration based on your planned dosing frequency. This can help frame medication reconciliation discussions and opioid rotation planning.
3) Always combine with patient-specific factors
- Age and frailty
- Renal or hepatic impairment
- Concurrent sedatives (especially benzodiazepines or alcohol)
- Sleep apnea or chronic lung disease
- Opioid tolerance level and prior adverse effects
Major limitations and safety notes
Opioid conversion is not purely arithmetic. Two patients with the same calculated MME can respond very differently. This calculator does not include methadone or transdermal fentanyl conversions, which are more complex and nonlinear.
It also does not account for breakthrough dosing, active metabolites, formulation differences (immediate vs extended release), opioid-induced hyperalgesia, or substance use disorder risk stratification.
- Do not use this tool as a standalone prescribing reference.
- Do not self-adjust opioid doses using online calculators.
- Use formal clinical guidance and monitoring plans.
When urgent help is needed
Call emergency services immediately for severe sleepiness, slowed breathing, blue lips, inability to wake, or suspected overdose. If available, administer naloxone per local guidance.
For non-emergency concerns (withdrawal symptoms, uncontrolled pain, confusion about dosing), contact your prescribing clinician or pharmacist promptly.