This Radiolab episode delves into the fascinating journey of the International Prototype Kilogram, a platinum cylinder that was the global standard for weight for over a hundred years. It traces the evolution of measurement, starting from intuitive body-based units to the scientifically defined meter, and highlights the challenges of standardization. As the episode unfolds, it reveals the necessity of replacing the physical kilogram with a more accurate definition based on Planck's constant. The narrative uncovers the unexpected hurdles in maintaining a universal standard and the intricate scientific process behind redefining such a fundamental unit of measurement.