The Pondera Online project aims to collect and study ancient and medieval weights. No attempt for such a global corpus has been successful since the end of the 19th century. Dispersed objects, disparate information and imprecise data together constitute a major obstacle to a comprehensive approach. Therefore, the Pondera Online project is intended to fill a gap in the collection, standardization, and processing of these archaeological data, thanks to an open access database (https://pondera.uclouvain.be/).0In this framework, four annual workshops have been organised in Louvain-la-Neuve between 2016 and 2019, bringing together specialists in Greek, Roman, Byzantine and Islamic weights and measures. These meetings have led to a rich program of presentations and discussions, and to the preparation of several papers. Twelve of them are gathered in this first collective volume.