This term means court calculation on major military and state affairs. The imperial court here refers to the place for officials to deliberate on affairs of state in ancient China. The purpose of calculation prior to war was to work out a strategy based on the state’s strengths and weaknesses. Sunzi’s view was that war was not merely a contest on the battlefield, but was also influenced by political, economic and other factors. Court calculation thus had to take into account different war scenarios and review a full range of circumstances in the state. Court calculation was a necessary preparation for war.
Those who make court calculation before battle and win must have been thorough in the process. Those who make calculation before battle and lose must have been insufficient in the process. Thorough calculation leads to victory, insufficient calculation leads to defeat – to say nothing of no calculation at all! When I look at warfare in this way, victory and defeat become obvious. (The Art of War)