GDP is calculated using three main approaches, each focusing on a different aspect of economic activity. The production approach measures the value added at each stage of production. The income approach sums up all incomes earned by factors of production, such as wages, profits, rent, and interest. The expenditure approach, which is most commonly used, adds total spending on consumption, investment, government expenditure, and net exports. Although the methods differ, all three approaches should theoretically produce the same GDP value, as they reflect the same economic transactions from different perspectives.