MME Calculator (Morphine Milligram Equivalents)
Daily morphine milligram equivalents from an opioid dose using CDC conversion factors.
What it does
Morphine milligram equivalents, or MME, put different opioids on one scale so a daily dose can be compared with a safety threshold. Each drug has a conversion factor that reflects its potency relative to morphine. Multiply the milligrams taken in a day by that factor and you get the daily MME.
The tool above uses the conversion factors published in the CDC opioid prescribing guideline. Choose the drug, enter the dose per intake, and enter how many times a day it is taken. It returns the total daily MME and the caution band it falls into.
The numbers matter because risk rises with dose. Below 50 MME/day the guideline still calls for careful review, and at 50 MME/day or above it advises extra caution, closer follow up, and consideration of other options. At 90 MME/day or more the caution is strongest.
MME is a comparison and caution tool, not a dosing recipe. It is best used to review a patient's total daily burden, especially when several opioids are combined, when a short acting drug is taken around the clock, or when a long acting product is added.
One limit stands out. MME is not a method for switching from one opioid to another. Converting by ratio alone can cause harm because cross tolerance between opioids is incomplete, so an equianalgesic dose can be too strong. Clinicians use MME to see the size of a dose, and use a separate, careful, usually reduced starting dose when rotating drugs.
How to use
- Pick the opioid from the list.
- Enter the milligrams taken in one dose.
- Enter how many doses are taken each day.
- Read the daily MME, the total daily dose, and the caution band.
- For multiple opioids, repeat for each and add the MME totals.
- Use the result to review the total dose, not to plan a switch.
Formula
- dose
- Milligrams taken in one intake.
- doses per day
- Number of intakes in 24 hours.
- factor
- CDC conversion factor for the opioid.
- 50 MME/day
- Level where extra care is advised.
The conversion factors are codeine 0.15, hydrocodone 1, hydromorphone 4, morphine 1, oxycodone 1.5, and oxymorphone 3. For a person taking more than one opioid, work out each MME and add them. Transdermal patches need a different route specific calculation that this page does not cover.
Worked example
Example: oxycodone 10 mg three times a day
Oxycodone 10 mg per dose, 3 doses a day.
- Total daily dose = 10 mg x 3 = 30 mg per day.
- Oxycodone factor = 1.5.
- Daily MME = 30 x 1.5 = 45.0 MME/day.
- That sits under the 50 MME/day threshold, with review still advised at any dose.
Reference table
| Opioid | Factor |
|---|---|
| Codeine | 0.15 |
| Hydrocodone | 1 |
| Hydromorphone | 4 |
| Morphine | 1 |
| Oxycodone | 1.5 |
| Oxymorphone | 3 |
Limits
- Covers six common oral and injectable opioids, not every product.
- Does not include transdermal fentanyl or buprenorphine, which use other rules.
- Not a method for switching between opioids, because cross tolerance is incomplete.
- Uses the dose you enter, not a verified prescription history.
Common mistakes
- Adding the MME of two opioids without keeping each factor separate.
- Using MME to pick a starting dose when rotating drugs.
- Forgetting to multiply by the number of daily doses.
- Mixing milligram strengths, such as a 5 mg and a 10 mg tablet, without checking.
- Ignoring non opioid options that can lower the total dose.
Try it yourself
Quick checks. Answers sit tucked under each question.
Morphine 30 mg twice a day?
30 x 2 x 1 = 60 MME/day, above the 50 threshold.
Hydrocodone 10 mg twice a day?
10 x 2 x 1 = 20 MME/day.
Hydromorphone 4 mg once a day?
4 x 1 x 4 = 16 MME/day.
Questions
What is a high MME dose?
50 MME/day or more calls for extra care, and 90 MME/day or more is the highest caution zone.
Can I use this to switch opioids?
No. Cross tolerance is incomplete, so a direct ratio switch can be unsafe. A clinician sets a reduced dose.
Why is the codeine factor so low?
Codeine is a weak opioid that needs conversion in the body, so each milligram counts less.
Does MME apply to patches?
Fentanyl patches are handled with separate conversion guidance, not these factors.
Is a lower MME always safer?
Lower dose lowers risk, but sudden reduction in a tolerant patient also carries risk, so changes are made carefully.
How do I add two opioids?
Convert each to MME with its own factor and add the daily totals.