A web-based uncertainty calculator for metrology professionals is presented in this paper. The system incorporates a Monte Carlo (MC) engine in accordance with GUM Supplement 1 and optimal first-order propagation that complies with the Guide to the Expression of Uncertainty in Measurement (GUM). A case study, algorithms, and architecture are described in detail. The findings demonstrate enhanced transparency, clear report generation (in PNG/PDF format) suitable for ISO/IEC 17025 documentation, and strong agreement between analytical propagation and MC evaluation. The benefits of integrating statistical simulation and rigorous analytical propagation in an intuitive web-based platform are emphasized. Users can view the installed script file and make changes to continuously improve its functionality using the editor-like text window that outputs the calculation results.

2025 IMEKO TC-6 International Conference on Metrology and Digital Transformation