Opioid Conversion Calculator

How to use this opioid conversion calculator

What this calculator does

This calculator reproduces an equianalgesic conversion model in which every listed opioid and administration route is related to a reference dose equivalent to 10 mg of intravenous morphine. It lets you enter one daily dose, view the corresponding doses for the other listed routes, and apply an incomplete cross-tolerance reduction to the converted targets. It is an arithmetic comparison tool only. It does not determine a safe prescription, account for an individual patient's tolerance, organ function, drug interactions, formulation, dosing interval, pain cause, or monitoring needs. The CDC opioid prescribing guideline specifically cautions that equianalgesic conversions are estimates and should not be used mechanically to set a new opioid dose.

When to use it

Appropriate uses include checking the arithmetic behind an educational equianalgesic example, comparing how route changes affect nominal equivalent quantities, reviewing a proposed conversion with a pharmacist or clinician, and documenting a reproducible calculation for teaching or audit. It is not suitable for self-directed medication changes or for selecting a real-world patch, tablet strength, infusion rate, or dosing schedule without clinical review.

How to calculate

1. The calculator opens with a demonstration: Morphine (IV) = 20 mg/day and Incomplete cross tolerance = 25%. The displayed results and the immediately available XLSX file are based on that same frozen example.
2. Replace any one opioid/route value with the daily dose you want to treat as the source. The field you edit becomes the source automatically. Enter a plain decimal number using a period as the decimal separator; commas are accepted only as standard thousands separators.
3. Set Incomplete cross tolerance between 0% and 100%. The source dose itself is preserved, while each converted target is multiplied by the retained fraction, which is 100% minus the entered reduction.
4. Read the live summary and the Equianalgesic conversion table. The table separates the unadjusted arithmetic equivalent from the reduced target so the cross-tolerance step is visible rather than hidden.
5. Select Download Excel to export the current validated model as a true XLSX workbook. Select Reset to clear the demonstration and all calculated content. Reset may disable Download Excel until a complete valid source dose and percentage are entered again.

Input guide

Incomplete cross tolerance is a required percentage from 0 to 100; 25 is a realistic demonstration value. A higher percentage lowers every converted target while leaving the source unchanged. Do not type a negative percentage, a value above 100, scientific notation, or a decimal comma. Clinical sources often discuss reductions in the 25% to 50% range when rotating opioids, but the appropriate adjustment is patient-specific; the AHRQ PSNet opioid-transition discussion describes why incomplete cross-tolerance can require a lower new dose.

Each opioid field is a positive daily quantity and is editable. Morphine (IV), Morphine (oral), and Morphine (SC) represent intravenous, oral, and subcutaneous morphine. Example values in the opening state are 20, 45, and 22.5 mg/day respectively; editing any of them makes that route the source. Route matters because bioavailability and potency differ.

Diamorphine (SC), Oxycodone (oral), and Oxycodone (SC) are also entered in mg/day. The startup values are 15, 22.5, and 15 mg/day after the 25% target reduction. A common mistake is comparing oral and parenteral milligram amounts as though route had no effect; this calculator always uses the route-specific reference ratio.

Alfentanyl (SC) and Fentanyl (SC) are potent parenteral opioids, so their numeric milligram values are much smaller; the demonstration shows 1.5 mg/day and 0.3 mg/day. Entering an amount in the wrong unit can create a very large error. The calculator accepts milligrams only for these fields because that is how the reference conversion table is expressed.

Hydromorphone (oral) and Hydromorphone (SC) use 4 mg and 2 mg respectively as the reference-table equivalents to 10 mg IV morphine; the startup converted values are 6 and 3 mg/day. Codeine (oral) and Tramadol (oral) each use a 300 mg reference-table dose, producing 450 mg/day in the demonstration. These are arithmetic outputs from the chosen table, not recommendations about whether those drugs are appropriate.

Fentanyl (transdermal) and Buprenorphine (transdermal) follow the reference table's 0.300 mg and 0.400 mg equivalents to 10 mg IV morphine, so the startup values display as 0.45 and 0.60 mg/day after reduction. Transdermal products are commonly labeled in units such as micrograms/hour, so treating these displayed milligram figures as a patch-setting instruction would be a unit error. For broader context on why opioid equivalence and opioid rotation are not interchangeable, see the UCSF explanation of oral morphine equivalents.

Output guide

Source identifies the opioid/route field most recently edited. Cross-tolerance reduction repeats the entered percentage. IV morphine reference and Unadjusted IV morphine equivalent report the common normalization quantity before any target reduction. Oral morphine equivalent reports the current oral-morphine row after adjustment unless oral morphine itself is the source, in which case the source amount is preserved. Dose retained after reduction is exactly 100% minus the cross-tolerance percentage, and Converted targets counts the 13 non-source routes.

In the table, Reference dose = 10 mg IV morphine is the fixed ratio used by the model. Unadjusted equivalent is the direct equianalgesic result before cross-tolerance. After cross-tolerance is the reduced target; the source row remains unchanged. Status distinguishes the source from converted targets. A zero source dose is accepted as the mathematical lower boundary and produces zero equivalents; it represents no source opioid exposure rather than a clinically useful rotation case. Invalid, negative, or nonfinite input clears the calculated outputs and blocks export.

Worked example

With the opening example, 20 mg/day of IV morphine corresponds to two reference units because the reference table defines 10 mg IV morphine as one unit. Unadjusted oral morphine is therefore 2 × 30 = 60 mg/day. A 25% incomplete cross-tolerance reduction retains 75% of the converted target, so 60 × 0.75 = 45.00 mg/day. Subcutaneous morphine is 2 × 15 = 30 mg/day before reduction and 22.50 mg/day after reduction. The source IV morphine field remains 20 mg/day because the reduction applies to the new converted target, not retroactively to the source amount.