Aggregate demand
Also known as: AD
Aggregate demand is the total quantity of goods and services demanded across an entire economy at each price level. It is the sum of consumption, investment, government spending, and net exports (AD = C + I + G + NX).
Aggregate demand (AD) measures the total spending on an economy's final goods and services at every possible price level over a given period. It has four components: consumption by households, investment by businesses, government spending, and net exports (exports minus imports) — summarized as AD = C + I + G + NX.
The aggregate demand curve slopes downward: when the overall price level falls, the quantity of output demanded rises. Three effects explain this. The wealth effect — lower prices raise the purchasing power of money holdings, so households spend more. The interest rate effect — lower prices reduce the demand for money, pushing interest rates down and stimulating investment. And the exchange rate (net export) effect — lower domestic prices make exports relatively cheap, so foreign buyers purchase more.
Changes in the price level move the economy along the AD curve, but changes in any spending component shift the whole curve. Rising consumer confidence, tax cuts, higher government spending, or a booming foreign economy shift AD right; pessimism, tax increases, or falling wealth shift it left. Combined with aggregate supply, aggregate demand determines an economy's equilibrium output and price level — the core model for analyzing recessions, inflation, and fiscal and monetary policy.
The AP Macroeconomics exam builds much of its free-response and multiple-choice material around drawing and shifting the AD curve, and the CGMA/CIMA business economics syllabus tests how policy tools work through aggregate demand.
Key takeaways
- Aggregate demand is total spending on final goods and services: AD = C + I + G + NX.
- The AD curve slopes downward because of the wealth, interest rate, and exchange rate effects.
- A change in the price level moves along the curve; a change in a spending component shifts the entire curve.
- AD and aggregate supply together determine equilibrium output and the price level.
- Fiscal and monetary policy influence the economy primarily by shifting aggregate demand.