This calculator is undergoing validation. Opioid conversions vary by source and require clinical judgment. Cross-check all calculations against institutional protocols and patient-specific factors before use. Methadone and fentanyl conversions require particular care.
Opioid Conversion Calculator
Equianalgesic dose conversion with cross-tolerance adjustment and total daily morphine equivalent (MME) calculation. For adult patients.
Converts a single source opioid to a single target opioid. Includes cross-tolerance adjustment.
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Cross-tolerance adjustment
Most guidelines recommend reducing the calculated equianalgesic dose to account for incomplete cross-tolerance between opioids. Adjust based on patient-specific factors.
50% reduction is commonly recommended for routine opioid rotation in stable patients. Consider 25% for opioid-naive patients or pain crises. Consider greater reduction (50–75%) for elderly patients, hepatic/renal impairment, or when converting from very high doses.
Breakthrough dosing (optional)
Enter a source dose to see the equianalgesic conversion.
References
- Centers for Disease Control and Prevention. CDC Clinical Practice Guideline for Prescribing Opioids for Pain — United States, 2022. MMWR Recomm Rep. 2022;71(3):1–95.
- Argoff CE, Silvershein DI. A comparison of long- and short-acting opioids for the treatment of chronic noncancer pain: tailoring therapy to meet patient needs. Mayo Clin Proc. 2009;84(7):602–612.
- McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. American Society of Health-System Pharmacists; 2018.
- Fudin J, Atkinson TJ. Opioid Conversion Calculations: A Tutorial. PainEDU. 2014.
- HHS Inter-Agency Task Force on Pain Management. Pain Management Best Practices. 2019.
- Manchikanti L, Singh A. Therapeutic opioids: a ten-year perspective on the complexities and complications of the escalating use, abuse, and nonmedical use of opioids. Pain Physician. 2008;11(2 Suppl):S63–88.
This calculator is intended for use by licensed pharmacy and healthcare professionals as an aid in opioid conversion calculations for adult patients. Equianalgesic conversions are approximations based on population averages and do not account for individual patient factors, including but not limited to: prior opioid exposure, organ function, drug interactions, age, comorbidities, genetic variation in opioid metabolism, and clinical context. Cross-tolerance is incomplete and variable between patients.
The calculated doses should be considered starting points for clinical decision-making, not definitive recommendations. Individualize dosing based on patient response, monitor closely for both efficacy and toxicity, and adjust as needed.
This calculator should not be used for: pediatric patients, opioid-induced respiratory depression management, opioid use disorder treatment (methadone or buprenorphine maintenance), or conversion of buprenorphine. Methadone conversions in particular require specialist expertise and should not rely on calculator output alone.
When in doubt, consult a pain specialist, palliative care clinician, or your institution's pain management team.