Opioid Calculator

Conversion Data and Methods

The data upon which the conversions are based are summarized in the table below. All conversions (except methadone) are made by first calculating the morphine equivalent of the opioid being converted from, and then calculating the specific dose of the opioid being converted to. The formulae for converting methadone are in the footnotes of the table.

Opioid Conversion Table1

Opioid Equianalgesic Doses:
Parenteral (IV, IM, SQ2, TD)
Equianalgesic Doses:
Morphine 10 mg 30 mg
Codeine 100 mg 165 mg
Fentanyl2 0.1 mg3 Not available
APAP/Hydrocodone Not available 30 mg
Hydrocodone ER Not available 30 mg
Hydromorphone 1.5 mg 7.5 mg
Levorphanol Not available 4 mg
Meperidine 100 mg 300 mg
Methadone Not available Use formulae listed in footnotes4
Oxycodone Not determined 20 mg
Oxymorphone 1 mg 10 mg
Tapentadol Not available 100 mg
Tramadol Not available5 Not available5
Partial Agonists6    
Butorphanol 2 mg Not available
Nalbuphine 10 mg Not available
Pentazocine 60 mg 150 mg

Prepared by: Ruth Perkins, B.S., M.A., Pharm.D., BCPS.
Rev: 014/2012 Updated: 2/2018 (J. Fudin/J. Gudin)


1 When converting patients from one opioid to another it is recommended to decrease the dose of the new opiate in half (after calculations) due to incomplete cross-reactivity between opiates in terms of analgesia and respiratory depression.  Titrate up as necessary.

2 Fentanyl and buprenorphine are not to be administered by the subcutaneous route due to poor absorption.

3 If a patient on fentanyl (transdermal) is to be transitioned to another opioid, the morphine equivalent is: Fentanyl (transdermal) 25 mcg/hr = 45 mg morphine (oral)
If a patient is on morphine (oral), the fentanyl (transdermal) equivalent is: Morphine (oral) 90 mg = 25 mcg/hr fentanyl (transdermal)
Equivalencies used are different because the authors recognize that conversion may not be bi-directionally equivalent, and therefore, adjustments have been made so that conversions to or from fentanyl remain conservative.

4 Methadone Fudin Factor (Developed by Dr. Jeffrey Fudin and Jason Andrew Fudin, B.Eng., MS)
Formula when converting to methadone: Methadone mg = X/21 {5.7- 3*sin [90/((110/x)5 + 1)] - sin [90/((320/x)7 + 1)]}
Formula when converting from methadone: Methadone mg = X/21 {5.7- 3*sin [90/((110/x)^5 + 1)] - sin [90/((320/x)^7 + 1)]}

5 Tramadol’s mu receptor binding affinity is 6000x less that of morphine.  Even opioid-naive patients may receive the highest dose.  Conversion to a scheduled opioid is not feasible for the purposes of this calculator because of the magnitude of difference in opioid receptor binding affinity between tramadol and other opioid agonists.

6 As of December 2018, this online opioid calculator no longer includes conversions to or from buprenorphine. Read more.

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