Forex is commonly traded in specific amounts called lots. Typically, a standard lot represents 100,000 units of the base currency.
Let’s consider the example of USD/JPY, where the base currency is USD. In this case, one lot in USD/JPY is equivalent to 100,000 USD. Similarly, in GBP/USD where GBP is the base currency, a lot is valued at 100,000 GBP. In EUR/USD, a lot would be worth 100,000 EUR.
Note that there are also variations of the standard lot size. These include the mini lot, which equals one tenth of a standard lot, or 10,000 units of the base currency. There is also the micro lot, which is one hundredth of a lot, or 1,000 units of the base currency.