Abstract. Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and to design mitigation measures. Despite its importance, it is not always applicable due to its expensiveness, and the need of integration with additional sensors for monitoring factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a datalogger, a power system and multiple digital and analog inputs. The system is equipped with a high precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associate accuracy of ±1 mm and integrates an operating temperature sensor that should allow to identify and correct potential thermal drift that typically affects this kind of systems. Field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.