Background: Paediatric drug calculators (PDCs) intended for clinical use qualify as medical devices under the Medical Device Directive and the Medical Device Regulation. The extent to which they comply with European standards on quality and safety is unknown. Objective: Determine the number of PDCs available as mobile applications for use in the Netherlands that bear a CE mark and explore the factors influencing the CE marking of such devices among application developers. Methods: A scoping review of the Google Play and App stores was conducted to identify PDCs available for download in the Netherlands. CE accreditation of the sampled applications was determined by consulting the application landing pages on application stores, by screening the United Kingdom Medicines and Healthcare products Regulatory Agency online registry of medical devices and by surveying application developers. The barriers to CE accreditation were also explored through a survey of application developers. Results: Out of 632 screened applications, 74 were eligible, including 60 paediatric drug dosage calculators and 14 infusion rate calculators. One application was CE marked. Of the twenty (34%) respondents to the survey, eight considered their application not to be a medical device based on its intent of use or functionality. Three developers had not aimed to make their application available for use in Europe. Other barriers that may explain the limited CE accreditation of sampled PDC applications included poor awareness of European regulations among developers and a lack of restrictions when placing PDCs in application stores. Conclusions: The compliance of paediatric drug calculators with European standards on medical devices is poor. This puts clinicians and their patients at risk of medical errors resulting from the largely unrestricted use of these applications.