Objective To demonstrate a process of calculating the maximum potential morphine milligram equivalent daily dose (MEDD) based on the prescription Sig for use in quality improvement initiatives. Methods To calculate an opioid prescription’s maximum potential Sig-MEDD, we developed SQL code to determine a prescription’s maximum units/day using discrete field data and text-parsing in the prescription instructions. We validated the derived units/day calculation using 3,000 Sigs, then compared the Sig-MEDD calculation against the Epic MEDD calculator. Results Of the 101,782 outpatient opioid prescriptions ordered over one year, 80% used discrete-field Sigs, 7% used free-text Sigs, and 3% used both types. We determined units/day and calculated a Sig-MEDD for 98.3% of all prescriptions, 99.99% of discrete-Sig prescriptions, and 81.5% of free-text-Sig prescriptions. Conclusion Analyzing opioid prescription Sigs to determine a maximum potential Sig-MEDD provides greater insight into a patient’s risk for opioid exposure.