The expenditure method is the most widely used approach for estimating GDP. GDP is calculated by summing expenditures on final goods and services, including:
1) Consumer spending (C)
2) Government spending (G)
3) Business investment (I)
4) Net exports (Exports - Imports) (NX)
Using this formula: GDP = C + G + I + NX
Several expenditures are excluded from this calculation, such as purchases of used goods, financial assets, and transfers. The document provides examples of calculating GDP using expenditure data.