When calculating GDP using the income approach, all expenditures in an economy equal the total income from producing goods and services.

Then, calculate adjustments for income, such as contributions to an IRA or the deduction for self-employment taxes. Subtract these from total income and claim the standard deduction.

Yet if you're like millions of Americans whose sole source of income comes from their job, you can typically calculate your adjusted gross income from your pay stub.

Calculating gross domestic product, or GDP, with the expenditure approach is the same as the formula for aggregate demand.