Pharmacology

Opioid Conversion Calculator

Converts a dose of one opioid to its oral morphine equivalent and then to an equivalent dose of another opioid and route.

Educational demonstration only — not safe for clinical use

This calculator reproduces a simplified equianalgesic model with known defects, listed below. It applies no reduction for incomplete cross-tolerance, which real practice requires (commonly 25–50%, and more when rotating to methadone). Every opioid rotation must be checked against a current institutional protocol and a pharmacist or prescriber.

Hydromorphone · oral

2.00mg

Dose within typical range

Convert from

Opioid

Route

Dose

Single dose, in milligrams.

Convert to

Opioid

Route

Try an example

Working

Every step of the conversion, so the arithmetic can be checked.

Morphine oral dose10mg

× drug factor to oral morphine1

× route factor (oral)1

= oral morphine equivalent (MME)10.0mg

÷ drug factor for Hydromorphone5

÷ route factor (oral)1

= Hydromorphone oral dose2.00mg

Cross-tolerance reduction appliedNone

not applied

Conversion factors used

Multipliers to oral morphine equivalent, as implemented on this page.

Opioid	Factor to oral morphine	Routes offered
Morphine	× 1	Oral, Intravenous, Subcutaneous
Hydromorphone	× 5	Oral, Intravenous, Subcutaneous
Oxycodone	× 1.5	Oral
Fentanyl	× 100	Intravenous, Transdermal
Methadone	× 4	Oral, Intravenous
Codeine	× 0.15	Oral

Route factors: oral ×1, intravenous ×3, subcutaneous ×3, transdermal ×1, rectal ×1. The fentanyl factor of 100 is an intravenous mcg-to-mg style ratio and is not valid for a patch.

The dose is taken to oral morphine and back out again:

MME = dose × drug factor × route factor

target dose = MME / (target drug factor × target route factor)

The interpretation band is read off the converted dose: below 1 mg it warns the figure is very low, above 200 mg it warns about tolerance, and anything between is called typical.

What is missing. Real practice reduces the calculated dose by roughly 25–50% for incomplete cross-tolerance, uses dose-dependent ratios for methadone rather than a single factor of 4, and converts transdermal fentanyl from mcg/h using a separate table. None of that is implemented here. These are faults in the original tool, preserved so the migration changes no numbers, and recorded in the project's issue tracker.

Common questions

No. It applies no cross-tolerance reduction, mishandles transdermal fentanyl and uses a single fixed ratio for methadone. Use your institution's equianalgesic protocol and have the calculation checked independently.

First-pass metabolism. Roughly a third of an oral morphine dose survives to the systemic circulation, so 10 mg IV is about as potent as 30 mg by mouth. That is the route factor of 3 used here for IV and subcutaneous.

Its conversion ratio rises with the morphine dose being switched from — it can be 4:1 at low doses and 20:1 or more at high ones — and it has a long, variable half-life that causes accumulation over days. A single fixed factor, as used here, is unsafe at any dose.

Total daily MME is the standard measure of a patient's overall opioid burden. Guidelines set review thresholds against it — for example reassessing the plan above 50 MME a day and avoiding or carefully justifying 90 MME a day.

Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy