合计 means 'to add up' or 'to total' — it refers to the act of calculating a sum, especially in practical, everyday contexts like counting money, tallying items, or computing figures. The character 合 (hé) conveys 'together' or 'jointly', while 计 (jì) means 'to calculate' or 'to count'; together, they literally mean 'to jointly calculate'. This word is commonly used in spoken and written Chinese when summarizing quantities, whether in informal conversations ('How much do these three items合计?') or formal settings like receipts, reports, or accounting.

As a verb, 合计 typically appears before or after the noun phrase being totaled, often followed by a number or measure word. It can also function as a noun meaning 'the total amount', especially in financial or administrative contexts. Unlike more formal synonyms like 總計 (zǒng jì), 合计 feels neutral and widely appropriate across registers — from a market vendor totaling your purchase to an office worker reviewing expenses.