Opioid (MME) Conversion Calculator

How Do You Calculate Opioid MME (Morphine Milligram Equivalents)?

MME shows an opioid dose in terms of oral morphine, so that different opioids can be compared on one scale. You calculate it by multiplying each dose by its conversion factor and adding the results for the day. Clinicians use the total to check how much opioid a patient is taking and whether that level is safe. This page covers the formula, the CDC conversion factors, the fentanyl patch and methadone special cases, and the risk levels. 

What Is MME (Morphine Milligram Equivalents)?

MME is a way to write any opioid dose in terms of the same strength of oral morphine. Different opioids are not equally strong, so a small dose of one drug can match a large dose of another. MME puts them all on one scale, using morphine as the standard. Morphine has a factor of 1. A drug that is five times as strong has a factor of 5. Once every opioid is written in morphine equivalents, the care team can see a patient's total opioid load at a glance. MME is a measure for safety review. It is not a rule for changing a patient's medicine.

Why Does MME Matter for Opioid Safety?

A higher total daily MME is linked to a higher risk of serious harm, such as slowed breathing and overdose. When every opioid is written in one unit, a prescriber can quickly see when a total is high. That number helps the care team decide what to do next, such as offering naloxone, checking a prescription monitoring program, or planning a slow and careful reduction. The point of MME is not to judge one drug on its own. It is to show the full picture of how much opioid a person takes each day. These ideas follow the CDC Clinical Practice Guideline for Prescribing Opioids for Pain.

What Is the Formula to Calculate MME per Day?

The formula is short and clear.

MME per day = dose in mg x MME conversion factor (added up for every opioid)

For each opioid, you take the daily dose in milligrams and multiply it by that drug's conversion factor. If the patient takes more than one opioid, you do this for each one and add the results. The final number is the total MME per day, and that single total is what the care team reads against risk levels. The formula gives a risk number. It does not tell you how to swap one drug for another.

How Do You Calculate MME Step by Step?

Here is one example.

1.     Take the daily dose. Say a patient takes 20 mg of oxycodone per day.

2.     Multiply by the conversion factor. Oxycodone's factor is 1.5, so 20 times 1.5 is 30.

3.     Read the result. The dose is 30 MME per day.

That number is a risk value for review. It is not a dose of any other drug.

How Do You Calculate Total MME When a Patient Takes More Than One Opioid?

Many patients take more than one opioid. To find the total, work out the MME of each drug, then add them together. For example, if one opioid comes to 30 MME per day and another comes to 45 MME per day, the total is 75 MME per day. The total, not any single drug, is what you compare against risk levels. Adding them gives the full daily opioid load.

What Are the CDC Opioid MME Conversion Factors?

The CDC publishes conversion factors for common opioids, and you use them to work out the MME number. The table below lists the factors for common oral opioids.

These factors are for working out the risk number only. The CDC states they do not tell you how to switch a patient from one opioid to another. Fentanyl patches and methadone are special cases and are covered below. Source: CDC Clinical Practice Guideline, 2022.

How Is the Fentanyl Patch MME Calculated?

A fentanyl patch is not dosed like a pill. It is measured in micrograms per hour, and the drug passes through the skin over time. Because of this, it uses its own method. The common approach is to multiply the patch rate in micrograms per hour by about 2.4 to estimate the MME per day. For example, a 25 micrograms per hour patch is about 60 MME per day. Other fentanyl forms, such as sprays and tablets, use their own factors. This is an estimate for risk review, not an exact dose.

Why Is Methadone MME Not a Simple Multiplication?

Methadone does not use one fixed factor. Its strength compared to morphine rises as the daily dose rises, so the link is not a straight line. This makes methadone harder to judge and easier to get wrong. Because of this, methadone should be handled by a specialist, and any change that involves methadone is outside a simple calculator. If methadone is part of a regimen, treat the MME estimate with extra care and rely on expert input.

What MME per Day Levels Signal Higher Risk?

Older CDC guidance from 2016 pointed to two levels. It flagged extra caution at 50 MME per day and above, and named 90 MME per day and above as a level to avoid or carefully justify. In 2022, the CDC updated its guidance and moved away from firm limits. The new approach focuses on each patient and on shared decisions between the patient and the care team. So these numbers are best seen as prompts for a closer look, not as hard cut-offs. At higher totals, guidance points toward offering naloxone, checking monitoring programs, and planning a careful reduction, rather than raising the dose.

What Are the Limits of the MME Calculator?

It helps to know what the tool cannot do.

•        The result is an estimate and does not replace clinical judgment.

•        There is no completely safe opioid dose.

•        The calculation is for oral opioids and not for changing an IV dose to an oral one.

•        For combination products, such as a pill that mixes an opioid with acetaminophen, enter only the opioid part.

•        Do not use it for children, because their bodies absorb drugs in less predictable ways.

•        Buprenorphine is a partial agonist, and its overdose risk does not rise with dose in the same way, so it is often left out.

•        The factors are for risk assessment, not for switching a patient from one opioid to another.

How Does MME Fit Into Safer Opioid Prescribing and Pain Management?

MME is one part of safer prescribing, not the whole of it. Along with the MME number, a care team checks for risky drug combinations, uses correct dosing math, and follows current guidance. Reading the total MME helps flag when to slow down and look closer. The tools below cover the other conversions and checks that sit next to MME in day to day care.

What Is a Drug or Medication Conversion Calculator?

A drug or medication conversion calculator groups clinical tools for different drug classes in one place. It is the parent page for conversions like the ones here. See the drug or medication conversion calculator.

How Do You Convert Micrograms to Milligrams?

Some opioids, such as fentanyl, are dosed in micrograms, not milligrams. There are 1000 micrograms in 1 milligram, so unit care matters when you read a dose. See the micrograms to milligrams calculator.

How Do You Calculate a Nursing Dosage?

Nursing dosage math checks that the ordered dose matches what is on hand, using standard formulas. It is a core safe dosing skill. See the nursing dosage calculator.

How Do You Convert mg to mL for a Liquid Medication?

A liquid medicine has a strength written in mg per mL. To find the volume, divide the ordered milligrams by that strength. See the mg to mL calculator.

Why Should Opioids and Benzodiazepines Not Be Combined?

Taking opioids and benzodiazepines together raises the risk of slowed breathing and overdose, which is why CDC guidance warns against the mix. It is a safety check that sits right next to MME review. See the benzodiazepine conversion page.

How Do You Calculate a Weight-Based (mg/kg) Dose?

Many medicines are dosed by body weight, in milligrams per kilogram. You multiply the patient's weight by the per kilogram dose to get the amount. See the weight-based dosing calculator.