Abstract— This study aims to develop an Arduino-based Sit Up test measuring instrument and an Ultrasonic sensor with an Android application, with the hope of providing effectiveness and efficiency in calculating Sit Up tests with more accurate calculation results. This type of research is Research and development. Research and development methods are research methods used to produce certain products, and test the effectiveness of the products. The development of the Sit Up test measuring instrument was first validated by electrical experts and measurement test experts. After that, it was continued with a small group test of 10 people and a large group test of 20 people. The results of the study obtained validity from electrical experts with an assessment percentage of 88.8% or in the "Good/Decent" category and the validity of test and measurement experts with an assessment percentage of 94% or in the "Good/Decent" category. Furthermore, the reliability test results obtained a small group value of 0.995 or in the "Very Strong" category and a large group of 0.996 or in the "Very Strong" category. Thus, it can be concluded that the Arduino-based Sit Up test measuring instrument and the Ultrasonic sensor with the Android application are declared suitable for use for the Sit Up test in producing more accurate calculations.

This study aims to create a sit-up measurement tool based on digital technology that can provide the effectiveness and efficiency of testors and testees. firstly validated by an electrical expert and a test and measurement expert. Continue the small group test of 10 people and a large group of 20 people. Based on the results of the study showed that the Digital Technology-based Sit Up Test Measure was categorized as "Good / Eligible" as a sit-up test. The results were obtained from the validation of the 88.8% good / proper electro expert and the 94% good test and measurement expert / feasible. Thus the conclusion that the Digital Technology-based Sit Up Test Measurement Tool has been declared feasible to be used for future tests and measurements both testee and testor. Keywords: sit up test measurement tool