One way to calculate GDP is the income approach, which

1 There are three ways of calculating GDP - all of which in theory should sum to the same amount:

2 National Output = National Expenditure (Aggregate Demand) = National Income.

3 (i) The Expenditure Method - Aggregate Demand (AD)

4 GDP = C + I + G + (X-M) where.

5 The Income Method - adding together factor incomes.