The practice of informal torn-money exchange remains prevalent in traditional markets despite the availability of official exchange services provided by authorized financial institutions. This study aims to examine the legal culture underlying informal torn-money exchange practices at Pasar Sabtu, Selat District, Kapuas Regency, Central Kalimantan, and to analyze their conformity with Islamic law and Indonesian monetary law. This research employed an empirical legal design using a socio-legal approach. Data were collected through observations, in-depth interviews with money exchangers, traders, community members, and banking officials, as well as document analysis, and were analyzed using a qualitative descriptive method. The findings reveal that the persistence of informal exchange practices is driven by pragmatic legal culture, where accessibility, efficiency, and convenience are prioritized over compliance with religious and state legal norms. From the perspective of Islamic law, the practice contains elements of ribā al-faḍl, gharar, and ambiguity of contract, making it inconsistent with the principles of al-ṣarf. Simultaneously, it contradicts Law Number 7 of 2011 on Currency, which guarantees the exchange of damaged banknotes at their full nominal value through authorized institutions. This study contributes to socio-legal scholarship by demonstrating that informal financial practices represent an ongoing negotiation between Islamic law, state law, and local legal culture in responding to community economic needs. The study is limited to a single research location; therefore, broader comparative studies are recommended to strengthen the generalizability of the findings.