There is little empirical data on the extent of home numeracy practice using technology, though previous research shows that home numeracy activities are linked with children's mathematics abilities. This study describes the process of constructing an inventory of digital home numeracy practice (DHNP-i). Parents (n = 126) of elementary children participated in the study. Psychometric assessments (such as internal consistency of items, composite reliability, convergent validity) were used to validate the scale, which measures the frequency of DHNP, parents' role in common DHNP (e.g., mobile math games/apps), how math apps are selected, math app types, supports provided by math apps, and parental perceptions of math app effectiveness. The results suggest that the DHNP measurement model (consisting of 19 items and five constructs) underlying the scale is a reliable and valid tool to assess home numeracy practice using technology. The newly developed scale will ultimately help researchers explore the impact of DHNP on young children's mathematics development.