If you’re searching for an opioid conversion calculator, you’re likely planning a switch morphine to hydromorphone, fentanyl patch to oral morphine, or a dose change after side effects. This guide de-jargonizes equianalgesic math, explains MME (morphine milligram equivalents), and shows safe, step-wise conversion with the same language clinicians use at the bedside.
👉 When you’re ready to run the numbers, use the calculator here: Opioid Conversion Calculator
What “opioid conversion” really means
An equianalgesic conversion estimates a clinically comparable analgesic effect when changing opioid, route, or both (e.g., oral morphine → IV morphine; oral morphine → oral hydromorphone; fentanyl patch ↔ oral morphine). These tables and calculators are starting points, not final orders because patients vary widely and cross-tolerance is incomplete. Most reputable protocols recommend reducing the new opioid’s equianalgesic dose by ~25–50% and titrating to effect with rescue dosing.
A word on MME (morphine milligram equivalents)
MME is a risk-stratification metric not a dose-conversion recipe. U.S. guidance cautions against using fixed MME factors to directly convert a patient from one opioid to another for prescribing decisions; dose conversions should consider clinical context and patient factors.
A step-by-step way to convert opioids (that clinicians actually use)
- Clarify the goal. Why are you switching ineffective analgesia, adverse effects, formulary change, or route change?
- Find an equianalgesic estimate (from a trusted table/algorithm).
- Apply cross-tolerance reduction (commonly 25–50% less than the equianalgesic result).
- Choose a breakthrough dose (e.g., short-acting opioid, typically a fraction of the daily total) and reassess frequently.*
- Re-titrate based on pain relief, function, sedation, and adverse effects.
*Exact breakthrough strategies vary by source and patient setting; follow your local protocol.
High-value examples (you’ll see these again and again)
- Morphine (oral) → Hydromorphone (oral):
Common equianalgesic relationship ≈ : 30 mg oral morphine ≈ 7.5 mg oral hydromorphone. After you compute that estimate, reduce 25–50% for safety and titrate. - Morphine (oral) ↔ Morphine (IV):
A frequently used ratio is 3:1 (≈30 mg PO morphine per day ≈ , 10 mg IV per day), then apply cross-tolerance reduction when changing drugs and routes. - Fentanyl patch (mcg/hr) ↔ Oral morphine (mg/day):
Manufacturer-anchored tables map patch strengths to prior opioid totals (e.g., a 25 mcg/h patch typically corresponds to a moderate oral morphine daily dose range). Always confirm using an official conversion table and apply clinical judgment; fentanyl kinetics differ from PO opioids. - Methadone (special case):
Do not use simple fixed ratios. Methadone conversions are non-linear (the ratio changes with dose and prior exposure) and should be undertaken by clinicians familiar with methadone rotation or using a protocol that specifically addresses this drug. - Renal impairment pearls:
Active metabolites (e.g., morphine-6-glucuronide) can accumulate. Many references prefer fentanyl or cautious hydromorphone dosing in advanced CKD; tailor to the patient and monitor closely.
FAQs (pulled from what people ask repeatedly)
Each question has a crisp, standalone answer, allowing it to rank independently and serving as a quick refresher at the bedside.
Is an MME calculator the same as an opioid conversion calculator?
No. MME summarizes relative opioid exposure for risk discussions and policy thresholds; it is not intended as a patient-specific dose-switching method. For conversions, use an equianalgesic method plus a 25–50% reduction for incomplete cross-tolerance and titrate to effect.
How do you convert morphine to dilaudid (hydromorphone)?
A common reference is 30 mg PO morphine ≈ 7.5 mg PO hydromorphone. After calculating, cut the new opioid dose by ~25–50%, then reassess.
How do you convert fentanyl patch to oral morphine?
Use a manufacturer-based conversion table (e.g., Duragesic label) to identify the estimated oral morphine daily dose range, then individualize and apply safety reductions; fentanyl’s transdermal kinetics require careful monitoring.
Can I directly convert to methadone with a simple ratio?
Avoid simple ratios methadone is non-linear and dose-dependent. Conversions typically require experienced prescribers and conservative protocols.
What cross-tolerance reduction should I use when switching opioids?
Most institutional protocols recommend reducing by 25–50% from the equianalgesic estimate and then titrating to comfort/function. Choose the higher reduction for frailty, high doses, or safety concerns.
What’s the difference between oral and IV morphine?
A traditional 3:1 oral: IV relationship is often used (30 mg PO ≈ 10 mg IV per day), before applying cross-tolerance reduction if changing drugs.
Does renal failure change opioid choices?
Yes. Accumulation of active metabolites (e.g., with morphine) may increase toxicity in CKD. Many sources prefer fentanyl and cautious hydromorphone when renal clearance is reduced.
What about “morphine equivalent calculator” vs “MME conversion calculator”?
They’re often used interchangeably online, but best practice is: use MME for risk context, and use an equianalgesic method for clinical conversion with built-in safety reduction.
How do I switch from short-acting to long-acting within the same opioid?
Total the patient’s last 24-hour dose, convert to the long-acting formulation, reduce 25–50% if needed for safety, and provide a short-acting breakthrough option while you titrate. (Follow your local formulary protocol.)
How do I convert oxycodone to morphine (oral-to-oral)?
Equianalgesic tables vary slightly; example relationships and a worked conversion approach appear in institutional algorithms. Always apply a safety reduction and reassess frequently.
What’s the safest way to convert high-dose opioids?
High doses magnify inter-patient variability. Use the larger end of the cross-tolerance reduction (e.g., 50%+), consider split-day titration with monitoring, and escalate cautiously.
Where do fentanyl patches fit on an opiate equianalgesic chart?
Patch strengths are commonly mapped to ranges of prior daily oral opioid requirements; tables in the Duragesic label provide a structured, conservative approach for initiation.
Practical safety checklist
- Confirm indication and goals; document the reason for conversion.
- Calculate an equianalgesic estimate, then reduce 25–50% for incomplete cross-tolerance.
- Provide breakthrough medication and reassess sedation, pain relief, and function.
- Be extra cautious with methadone and fentanyl patches (non-linear kinetics, delayed steady state).
- Consider renal/hepatic function and drug interactions; adjust plan accordingly.
References
- CDC Opioid Prescribing Guideline use of MME and cautions on dose conversion.
- MD Anderson Adult Cancer Pain Algorithm equianalgesic examples and 25–50% reduction guidance.
- Duragesic (fentanyl patch) Prescribing Information conversion tables/considerations.
- Oregon Pain Guidance MED Calculator MED/MME caution (not a direct dose-conversion tool).
- Safe Use of Opioids in CKD renal considerations in opioid selection/dosing.
