The calculator allows for the automatic calculation of the relative values of currency units in medieval Livonia. It does so separately for three distinct periods, defined firstly by the transformation of the silver mark into a currency mark in the mid-14th century, and secondly by the coinage reform of 1422–1426.

In medieval Livonia, the same system of weight units was used throughout the region: 20 mark-pounds made up one Livonian pound (Lispfund), and 20 Livonian pounds made up one ship’s pound (Schiffpfund). The actual values of these units, however, varied between Livonian towns. The system was based on the Riga mark (approximately 208 g), twice the weight of which constituted the Riga mark-pound (approximately 416 g). At the Diet of Valga in 1460, it was agreed that one ship’s pound would correspond to 392 Riga mark-pounds in Tallinn, 396 in Tartu (and later also in Narva), 416 in Pärnu, and 410 in Viljandi. Consequently, the values of the Livonian pound and mark-pound in these towns differed from the Riga standard.