Kilovolt‑ampere reactive hour (kVAR·h) is the standard unit for measuring accumulated reactive energy in alternating‑current (AC) power systems, symbolized as kVARh. It quantifies the amount of non‑working (reactive) power—produced by inductive or capacitive loads—consumed over time, helping utilities and engineers track energy that does not perform useful work but is essential for maintaining voltage levels and system stability. In practice, kVAR·h is used on electric bills, load‑flow studies, and power‑factor correction designs to assess the efficiency of industrial plants, commercial buildings, and large‑scale renewable installations. Understanding and managing kVAR·h is crucial for reducing penalties, optimizing equipment sizing, and improving overall grid reliability, making it a key metric in both practical energy management and scientific analysis of AC power quality.