This Opioid Calculator Application is a tool for the calculation of total oral Morphine Equivalent Daily Dose (oMEDD). A particular design feature of the app is that it simplifies the calculation of oMEDD in cases where combinations of opioids are used. It is designed to provide easy accessibility and consistency to facilitate research, improve education and fill a void in the availability of reference conversion data in clinical practice. This opioid calculator is produced by the Faculty of Pain Medicine of the Australian and New Zealand College of Anaesthetists (FPM ANZCA) which is the peak body responsible for the education, training, continuing professional development and maintenance of standards of clinical practice for specialist pain medicine physicians in Australia and New Zealand.