What is a morphine milligram equivalent (MME)?

An MME is a standardized unit that expresses the potency of any opioid relative to oral morphine. For example, oxycodone has an MME factor of 1.5, meaning 10 mg oxycodone equals 15 mg oral morphine in analgesic effect.

Should I use this result directly when prescribing?

No. This tool is for educational and reference use only. When rotating opioids clinically, guidelines recommend reducing the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance. Always individualize therapy and consult clinical pharmacists or palliative care specialists.

How is fentanyl patch converted?

Transdermal fentanyl patches are dosed in micrograms per hour (mcg/hr). The approximate conversion is: daily oral MME divided by 2.4 = patch dose in mcg/hr. This calculator uses the reverse factor (2.4 mg oral morphine per mcg/hr per day) as widely cited in equianalgesic tables.

Why are methadone conversions excluded?

Methadone has a highly variable and nonlinear equianalgesic ratio that depends on the total daily morphine dose (ranging from 4:1 at low doses to 12:1 or more at high doses). Its long half-life and complex pharmacokinetics make a simple conversion factor dangerous. Methadone conversions should always be performed by experienced clinicians.

What sources do these conversion factors come from?

The MME factors are based on widely cited equianalgesic tables from the CDC Opioid Prescribing Guideline, clinical pharmacology references (Brunton et al., Goodman & Gilman), and the Washington Manual of Medical Therapeutics.

Is 90 MME/day considered high risk?

Yes. The CDC 2022 Clinical Practice Guideline notes that doses at or above 50 MME/day carry increased risk of overdose, and doses at or above 90 MME/day warrant careful reassessment. This calculator displays the total daily MME to help contextualize risk.

Opioid Conversion Calculator

Enter a current opioid dose and convert it to any other opioid using standardized MME equianalgesic ratios.

Dose Conversion Inputs

For educational reference only — see disclaimer below.

Current Opioid

Total Daily Dose (mg/day)

Convert To

Clinical disclaimer: This tool is for educational reference only. Always apply a 25-50% dose reduction for incomplete cross-tolerance when rotating opioids. Methadone is excluded due to nonlinear pharmacokinetics. Consult institutional guidelines and a clinical pharmacist before prescribing.

Enter a dose on the left and click Calculate

Equianalgesic Dose

Source

Total Daily MME

All Equianalgesic Equivalents

Based on MME/day

Opioid	Route	Daily Dose

Clinical note: These are theoretical equianalgesic doses. When rotating opioids, reduce the calculated target dose by 25-50% to account for incomplete cross-tolerance. Titrate based on patient response and pain assessment. Fentanyl patch doses are approximate; onset of steady state takes 12-24 hours.

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Summary

The Opioid Conversion Calculator converts doses between different opioid medications using standardized morphine milligram equivalent (MME) conversion factors. Clinicians can enter a current opioid and daily dose, then see the equivalent dose in any target opioid. This tool is intended for educational and reference purposes; always apply a 25-50% dose reduction when switching opioids in practice and consult clinical guidelines.

How it works

Select the opioid the patient is currently taking.
Enter the current total daily dose in milligrams (or micrograms for fentanyl patches).
Select the target opioid you want to convert to.
The calculator multiplies by the source MME factor and divides by the target MME factor.
Review the calculated equivalent dose alongside the total daily MME for safety context.
Apply a 25-50% dose reduction for incomplete cross-tolerance when rotating opioids clinically.

Use cases

Converting a patient from oral morphine to oxycodone when switching formulations.
Estimating equianalgesic doses during opioid rotation to minimize withdrawal.
Calculating total daily MME to assess opioid load against CDC prescribing guidelines.
Educational reference for pharmacology students learning equianalgesic dosing.
Comparing relative potency of different opioids for clinical decision support.
Transitioning from IV hydromorphone to oral opioids at hospital discharge.
Quick reference during palliative care consultations for dose conversion.
Verifying opioid dose equivalency calculations for medication reconciliation.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu