What is the formula for GDP?

GDP = C + I + G + (X − M): consumption, plus investment, plus government spending, plus exports minus imports. That is the expenditure approach, the one BEA publishes quarterly. Two other approaches — income and production — arrive at the same total from different sides of the same transactions.

Why are imports subtracted from GDP?

Because they were already added. A phone bought by a household is counted in consumption whether it was made in Ohio or Shenzhen, so the import subtraction removes the part that was not produced domestically. It is bookkeeping, not a judgement about trade.

What is the difference between nominal and real GDP?

Nominal GDP values this year’s output at this year’s prices; real GDP values it at a fixed base year’s prices. If output is flat and prices rise 3%, nominal GDP rises 3% and real GDP does not move. Growth figures in the news are real.

Does government spending include social security?

No. Transfer payments — social security, unemployment, Medicaid — are excluded from G, because no good or service is produced when the money moves. They enter GDP later, inside consumption, when the recipient spends them.

GDP Calculator

With consumption (c) 20700 usd, investment (i) 5200 usd, government (g) 5300 usd, exports (x) 3300 usd and 3 more fields, gdp comes to 30,200.0 $ billion — nominal gdp. It is reached in 8 steps, the last of which is 20700 + 5200 + 5300 + -1000, and each one is printed on the page with its numbers filled in. The formula is the one published by BEA, not an approximation fitted to it.

Gross domestic product by the expenditure approach, with the share each component contributes, real GDP after the price deflator, and GDP per head.

Formula and sources checked 2 September 2026 · How we check

30,200.0 $ billion

Nominal GDP for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.

It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.

Consumption (C)usdHousehold spending on goods and services. Roughly two thirds of US GDP. In billions.Investment (I)usdBusiness equipment and structures, housing, and the change in inventories. Not the purchase of shares — buying stock moves money, it does not produce anything.Government (G)usdGovernment consumption and investment. Transfers — pensions, benefits — are excluded, because they are counted when the recipient spends them.Exports (X)usdImports (M)usdSubtracted, because an imported good was already counted inside C, I or G and was not produced here.GDP price deflatorindexThe implicit price deflator, base year = 100. BEA publishes it in NIPA table 1.1.9; it was about 127 in 2025 against a 2017 base.Populationpeople

Nominal GDP

30,200.0 $ billion

Net exports (X − M): 3300 - 4300-1,000
Nominal GDP, $bn: 20700 + 5200 + 5300 + -100030,200
Real GDP, $bn at base-year prices: 30200 * 100 / 12723,779.528
GDP per head: 30200 * 1000000000 / 342000000$88,304
Consumption share: 20700 / 30200 * 10068.543
Investment share: 5200 / 30200 * 10017.219
Government share: 5300 / 30200 * 10017.55
Net exports share: -1000 / 30200 * 100-3.311

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Worked example

Net exports are 3,300 − 4,300 = −1,000, so the trade deficit subtracts a trillion dollars. GDP is 20,700 + 5,200 + 5,300 − 1,000 = $30,200 billion. Divided by a deflator of 127 that is $23,780 billion at base-year prices, and across 342 million people, $88,304 a head.

How to work it out yourself

1.Enter every figure in the same units. BEA publishes the components in billions of dollars at an annual rate, which is what the defaults use; a quarterly figure has to be annualised first or the answer is a quarter of the truth.
2.Subtract imports rather than leaving them out. An imported car sits inside consumption already — the subtraction removes it, it does not penalise trade. A rising trade deficit lowers measured GDP arithmetically, not economically.
3.Use the deflator when comparing years. Nominal GDP rises when prices rise even if nothing more is produced; real GDP is the same output priced at one year’s prices, and it is the only one of the two that answers "did the economy grow".

The formula

Net exports (X − M)3300 - 4300
Nominal GDP, $bn20700 + 5200 + 5300 + -1000
Real GDP, $bn at base-year prices30200 * 100 / 127
GDP per head30200 * 1000000000 / 342000000
Consumption share20700 / 30200 * 100
Investment share5200 / 30200 * 100
Government share5300 / 30200 * 100
Net exports share-1000 / 30200 * 100

Source: BEA — NIPA handbook, chapter 2: fundamental concepts, BEA — gross domestic product, current release

Questions people actually ask

What is the formula for GDP?: GDP = C + I + G + (X − M): consumption, plus investment, plus government spending, plus exports minus imports. That is the expenditure approach, the one BEA publishes quarterly. Two other approaches — income and production — arrive at the same total from different sides of the same transactions.
Why are imports subtracted from GDP?: Because they were already added. A phone bought by a household is counted in consumption whether it was made in Ohio or Shenzhen, so the import subtraction removes the part that was not produced domestically. It is bookkeeping, not a judgement about trade.
What is the difference between nominal and real GDP?: Nominal GDP values this year’s output at this year’s prices; real GDP values it at a fixed base year’s prices. If output is flat and prices rise 3%, nominal GDP rises 3% and real GDP does not move. Growth figures in the news are real.
Does government spending include social security?: No. Transfer payments — social security, unemployment, Medicaid — are excluded from G, because no good or service is produced when the money moves. They enter GDP later, inside consumption, when the recipient spends them.

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