Trade size refers to the number of units of a financial instrument that a trader or investor buys or sells in a transaction. It is often expressed in terms of lots in forex trading, where a lot is a standard unit of measurement used in forex trading to refer to a transaction size. One standard lot in forex trading represents 100,000 units of the base currency. A trader’s position size can have a significant impact on their potential profit or loss. Therefore, it is important to manage trade size and risk appropriately.