Quantum measurements that are informationally complete can uniquely determine an unknown quantum state, making them crucial for tasks like quantum state tomography. Researchers have introduced a characterization of informational completeness for arbitrary quantum measurements, providing a quantification method. This work focuses on qubit measurements and channels, exploring the preservation of informational completeness. The study's findings have implications for quantum computing and cryptography, as they can be used to better understand and develop quantum systems. The introduction of this quantification method allows for a more nuanced understanding of quantum measurements, enabling the development of more sophisticated quantum technologies. The ability to quantify informational completeness is essential for advancing quantum computing and cryptography, as it can help identify potential vulnerabilities and areas for improvement, so the development of robust quantum systems relies on a deep understanding of these concepts1.