What this narcotic conversion calculator does
This calculator estimates opioid conversions by using morphine milligram equivalents (MME) as a common reference point. The process is straightforward: convert the current opioid dose to MME/day, then convert that MME/day to an equianalgesic dose of a new opioid.
Because tolerance between opioids is not perfectly symmetrical, the tool also applies an optional cross-tolerance reduction percentage to produce a more conservative starting estimate.
How the math works
Step 1: Convert current opioid to MME/day
MME/day = Current daily dose × opioid conversion factor
Step 2: Convert MME/day to target opioid
Equianalgesic target dose = MME/day ÷ target opioid conversion factor
Step 3: Apply cross-tolerance adjustment
Suggested reduced dose = Equianalgesic target dose × (1 − reduction%)
Reference conversion factors used (oral)
- Morphine: 1.0
- Oxycodone: 1.5
- Hydrocodone: 1.0
- Hydromorphone: 4.0
- Oxymorphone: 3.0
- Codeine: 0.15
- Tramadol: 0.1
- Tapentadol: 0.4
Why opioid conversion requires caution
Equianalgesic tables are estimates, not guarantees. Two patients taking the same drug and dose can have very different responses. Sedation, respiratory depression risk, renal/hepatic function, age, drug interactions, and opioid tolerance history all matter.
- Always confirm route and formulation (immediate-release vs extended-release).
- Use lower starting doses in older or medically fragile patients.
- Reassess pain, sedation, and breathing after conversion.
- Review concurrent CNS depressants (benzodiazepines, alcohol, sedatives).
What this calculator does not cover
This page intentionally avoids highly complex or nonlinear conversions. In real-world practice, these cases often require specialist guidance:
- Methadone conversions (nonlinear potency at higher doses)
- Transdermal fentanyl conversions
- Buprenorphine products
- IV, epidural, intrathecal, or mixed-route conversions
- Incomplete or uncertain medication histories
Clinical best-practice checklist
Before converting
- Document current opioid, total daily dose, and schedule.
- Confirm indication and goals of therapy.
- Check renal/hepatic status and interacting medications.
After converting
- Start conservatively and monitor closely.
- Educate patient/caregiver on overdose warning signs.
- Arrange follow-up within an appropriate interval.
- Adjust dose based on response and adverse effects, not just table values.
Bottom line
A narcotic conversion calculator is best used as a decision-support aid, not an autopilot prescribing tool. The value is speed and consistency; the risk is overconfidence. Use the estimate as a starting point, then apply patient-specific clinical judgment and monitoring.