Equianalgesic Calculator (Opioid Conversion)

Select specific drugs and routes. Use the mouse wheel, touch drag, or click a wheel and type a letter to jump.

mg
From Click & type to jump
To
%

Calculated Target Dose

-- mg
25% Reduction Applied
Conversion Logic: Calculation based on standard equivalence tables.

Clinical Pearls

  • Cross-Tolerance: Incomplete cross-tolerance is common when switching opioids. A reduction of 25-50% is generally recommended for the new agent, unless pain is uncontrolled.
  • Methadone: Conversion to methadone is complex and non-linear. Higher morphine-equivalent doses require smaller conversion ratios. This calculator uses conservative estimates; refer to specific methadone protocols.
  • Fentanyl: IV Fentanyl doses are typically measured in micrograms (mcg). This calculator automatically adjusts units to mcg for Fentanyl to prevent calculation errors.
  • Patient Specifics: Always adjust for age, renal/hepatic function, and frailty. "Start low and go slow."

References

  1. CDC Clinical Practice Guideline for Prescribing Opioids for Pain. MMWR Recomm Rep 2022;71(No. RR-3):1–95.
  2. McPherson ML. Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. 2nd ed. Bethesda, MD: ASHP; 2018.
  3. CMS. Opioid Oral Morphine Milligram Equivalent (MME) Conversion Factors. 2023.
  4. Treisman GJ, Clark MR. A Guide to Chronic Pain Assessment and Management. Johns Hopkins University Press; 2011.