Question

why are only final goods and services counted?​

Answer 1

Only final goods are counted in measuring GDP because the goods used in making the final good are included in the final good, so it would be counted twice, otherwise. The value of used furniture that is bought and sold is not counted because the used furniture would have been included in GDP the year before.

Answer 2

Intermediate goods and services, which are used in the production of final goods and services, are not included in the expenditure approach to GDP because expenditures on intermediate goods and services are included in the market value of expenditures made on final goods and services.