Assessing students' mathematical achievement is essential for monitoring progress and refining instructional methods. This study focuses on developing and standardizing a Mathematics Achievement Test (MAT) for fourth-grade students, ensuring reliability and validity. Following a structured test construction process, including blueprinting, item analysis, reliability, validity, norms, the test assesses core mathematical skills such as arithmetic operations, fractions, and measurement. By aligning with curriculum standards and incorporating expert feedback, this research provides an effective tool for evaluating mathematics achievement. The standardized MAT aims to support educators in making standardize mathematics tests to enhance learning outcomes in elementary education.