C + I + G + (X − M) = 21,000, and the last bracket is negative here
The expenditure approach counts everything bought in final form: 14,000 of household consumption, 4,000 of investment, 4,000 of government spending, and net exports of 3,000 less 4,000 — a trade deficit of 1,000. The total is 21,000, and in the default figures those units are billions of dollars, roughly the scale of the United States.
Consumption dominates in most developed economies, typically two-thirds of output, which is why consumer confidence surveys move forecasts so much. Imports are subtracted not because trade is harmful but because they were already counted inside the other three: a household buying an imported car adds to consumption, and the subtraction removes output that was produced abroad.
The −1,000 here is an accounting subtraction, not a verdict
Net exports enter GDP as a single signed figure, so a country importing more than it exports reduces the total. That is arithmetic about where goods were produced, not a judgement about the economy. A deficit usually accompanies strong domestic demand — households wealthy enough to buy from abroad — and often sits alongside a capital account surplus as foreign money flows in the other direction.
It does mean the headline figure understates domestic consumption. An economy with 21,000 of GDP and a 1,000 deficit absorbed 22,000 of goods and services; it simply produced 1,000 of that elsewhere. That distinction matters when comparing living standards, where consumption per head is often more informative than output per head.
Expenditure, income and production must agree, and in practice never quite do
GDP can be measured by what was spent, by what was earned as wages, profits, rent and interest, or by the value added at each stage of production. In theory the three are identical, because every dollar spent is a dollar earned. In practice national statistics offices publish a statistical discrepancy, usually well under 1% of output, because the three are built from different surveys.
This calculator measures it two ways — by expenditure, the method most published data follows, and by income, which the method menu switches to. Where you see a headline figure revised months later, it is usually the reconciliation between the three approaches working through, and revisions of half a percentage point on quarterly figures are entirely routine.
Wages, rent, interest, profit, taxes and depreciation add to the same 21,000
Every dollar spent on final output is paid out to someone, so GDP can be built from the income side. Add the factor incomes — compensation of employees 11,000, rental income 700, net interest 600, corporate profits 2,700 and proprietors’ income 1,500 — for 16,500. Add taxes on production less subsidies, 1,500, which are part of what buyers pay but go to the government rather than to a factor of production: 18,000. Add depreciation, the capital used up in producing the output, 3,000: GDP is 21,000, the same total the expenditure method gives for this economy.
GDP = W + R + i + Π + mixed income + (T_ind − S) + depreciation
Courses in India and elsewhere name the subtotals: factor incomes are net domestic product at factor cost; adding net indirect taxes gives net domestic product at market prices; adding depreciation gives gross domestic product at market prices. The labour share — compensation over GDP, 52% here — is one of the most watched ratios the income side reveals.
Income method
11,000 + 700 + 600 + 2,700 + 1,500 = 16,500
16,500 + 1,500 = 18,000 (NDP at market prices)
18,000 + 3,000 = 21,000
GDP = 21,000
Measured from incomes, US output is published as GDI, and it never matches GDP exactly
The US Bureau of Economic Analysis publishes both measures every quarter: gross domestic product from spending and gross domestic income from incomes. They are equal in principle and differ in practice, because each is assembled from different surveys and tax records. The gap is published as the statistical discrepancy.
The gap can be large enough to matter for reading the economy. When GDP and GDI diverge, economists often average the two, and some research finds GDI an earlier signal of turning points. For a textbook problem the two methods should give identical answers, as they do on this page.
Unpaid work, environmental cost and everything informal
GDP measures market transactions in final goods. It therefore excludes unpaid household work and caring, which is a substantial share of real economic activity and is distributed very unevenly; the informal and cash economy, which in some countries exceeds a third of measured output; and any depletion of natural capital, so an economy cutting down its forests records the timber as output and the loss as nothing.
It also says nothing about distribution. Two economies with identical GDP per head can have completely different median incomes. None of this makes GDP a bad measure of what it measures — the volume of market production — but it makes it a poor single measure of welfare, which is what supplementary indicators such as the Human Development Index exist to address.
One period, nominal figures, and consistent units
Every input must cover the same period and be measured in the same units — mixing a quarterly investment figure with annual consumption produces a number that means nothing. The result is nominal unless the components entered were already inflation-adjusted; to get real GDP, deflate by a price index first, or use the GDP deflator page to convert between the two.
Intermediate goods must be excluded or output is double-counted: the steel in a car is already inside the car’s price. Second-hand sales are excluded too, since the item was counted when first produced. For published data, these adjustments are already made — this calculator assumes your inputs are final-demand figures.
Sources & References
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
What the calculation assumes
- Every dollar of output is captured by exactly one of the four spending categories, with no double counting.
- The figures entered are final spending on goods and services, not intermediate inputs that are resold.
- All components are measured in the same units and time period, typically annual dollars in billions.
Where it stops
- GDP omits non-market activity such as household labor, volunteer work, and the underground economy.
- It counts spending without judging whether that spending raises well-being, so it is not a welfare measure.
- A single headline figure hides distribution, environmental costs, and the quality of what is produced.