Heat flux is a critical parameter for understanding heat dynamics. Commercial heat flux meters have weaknesses because they can only detect heat flux with certain specifications depending on the heat source and work area. To answer these challenges, a prototype heat flux meter was developed using the 2D inverse heat conduction problem (IHCP) approach. The prototype consists of a thin copper plate equipped with thermocouples mounted on the plate and a software. When a heat flux acts on the plate, the instrumentation system will record its temperature distribution. The software then processes the measured temperature data to solve the IHCP using the Conjugate Gradient Method. This new measurement technique offers the advantage of accommodating any heat source and any heat flux area as long as the plate still encloses it. Using synthetic data, a temperature measurement error level of ± 0.5 °C will result in a heat flux measurement with a deviation of 1.09 %. The influence of thermal conductivity and dissipation coefficient on the accuracy of heat flux measurements will be evaluated. The research is still limited to the problem of 2D plate in steady state conditions. This prototype has the potential to be developed with transient conditions, 3D models and neural networks so that it can be applied to thermal inspection of industrial installations. © 2025