This tool is designed for the EVM (Error Vector Magnitude) budget analysis in the communication and RF (Radio Frequency) system engineering, where the RF and digital impairments of different sub-systems are often modelled and qualified as EVM in % during top-level design and analysis stage. The system engineer often evaluates the trade-offs between cascaded sub-systems to reach an feasible balance between cost, design effort and performance. This tool models 4 cascaded sub-systems with EVM effect modelled as additive noises. A simple EVM and SNR conversion calculator is also included. This will be a useful tool for RF and wireless system engineers and students.