Aggregate Demand
What is Aggregate Demand?
Aggregate demand is the total demand for final goods and services in an economy at a given time.
Aggregate demand is the sum of consumption, investment, government spending, and net exports. It represents the total amount of goods and services that households, businesses, the government, and foreigners plan to buy at a given level of income.
Aggregate Demand: a worked example
Add the components at a given price level. Suppose consumption is $520 billion, gross investment $180 billion, government purchases $250 billion, exports $95 billion and imports $145 billion. Net exports are $95 billion minus $145 billion, or negative $50 billion, so total planned expenditure is 520 + 180 + 250 - 50 = $900 billion. Now the government raises purchases to $270 billion, an injection of $20 billion. With an MPC of 0.6 the multiplier is 1 ÷ 0.4 = 2.5, so aggregate demand shifts right by 20 × 2.5 = $50 billion. At the original price level the quantity of real output demanded becomes $950 billion. Nothing in that shift depends on the price level, which is the point: the curve moves the same horizontal distance at every price level.
The mistake students make with aggregate demand
Three component errors cost points repeatedly. The first is adding imports rather than subtracting them. Imports are foreign production, so they enter only to remove spending that left the domestic economy. The second is dropping transfer payments such as unemployment benefits into G. Government purchases count spending on goods and services only, and transfers reach aggregate demand later through consumption, and only for the portion recipients spend. The third is counting the purchase of an existing house or a share of stock as investment. Only new capital, new construction and inventory changes belong in I.
Aggregate Demand questions
What are the four components of aggregate demand?
Consumption, investment, government purchases and net exports make up aggregate demand, written AD = C + I + G + (X - M). Consumption is household spending, investment is business spending on new capital plus inventory changes and new residential construction, government purchases exclude transfer payments, and net exports subtract imports from exports. A change in any component at a given price level shifts the whole curve.
Why does the aggregate demand curve slope downward?
Three effects explain the slope, and none of them is the substitution story used for a single good. The wealth effect: a higher price level erodes the real value of money households hold, so they consume less. The interest rate effect: a higher price level raises money demand and the interest rate, so investment falls. The net export effect: domestic goods become expensive relative to foreign goods, so exports fall and imports rise.
What is the difference between aggregate demand and demand?
Aggregate demand covers total planned spending on all final goods and services, plotted against the overall price level, while a demand curve covers one good plotted against that good's own price. The reasons for the slopes differ too. A single demand curve slopes down partly because buyers substitute toward other goods, but when the entire price level rises there is no other domestic economy to substitute into.
This is the live AD/AS Model sandbox. Drag the curves, or open the full version.
Related terms
Common comparisons
Get AP Econ exam tips in your inbox
Occasional emails with study tips, new interactive graphs, and exam-season reminders. Free, no spam.
No spam. Unsubscribe anytime. Read our privacy policy.
Keep track of what you have studied
A free EconLearn account adds progress tracking, your quiz history, and achievements. Studying here is free either way, and there is nothing to pay for as a student.
Create a free accountAlready have one? Sign in
Last updated