Missed Parkinson's disease (PD) medications when patients are admitted to hospital are associated with increased morbidity and mortality. Swallowing difficulties in hospitalised PD patients are common and should prompt clinicians to consider conversion of a patient's PD medications to a non-oral form – this is, however, recognised as a challenging area with potential for error. Northumbria Healthcare NHS Foundation Trust's PD service set out to address this patient safety issue through the development of an innovative online medication calculator (pdmedcalc.co.uk). This article summarises the development process underpinning the calculator, presents numerical data on the usage of the calculator and presents survey data relating to user experiences of the calculator. Lastly, we highlight how user feedback has been used to refine subsequent iterations of the calculator and how use of the calculator has rapidly spread beyond our trust because of it being freely accessible online.