GDP vs GDP growth rate: levels, rates and revisions

Separate the value of production from its growth

Gross domestic product, or GDP, measures the value of final goods and services produced within an economy during a period. It avoids counting intermediate inputs again as final output. Statistics offices combine business surveys, administrative records, and other source data to estimate production, spending, and income.

Current-price GDP values output using prices from the period being measured. It can increase because the economy produces more, because prices rise, or both. Real GDP adjusts for price changes to measure changes in the volume of production. Real GDP growth is the percentage change in that adjusted measure.

One expenditure view adds consumption, investment, government spending on goods and services, and exports, then subtracts imports. Imports are subtracted because imported production can already be included in the spending categories. This accounting step keeps the total focused on domestic production.

Narwhal's GDP endpoint returns current-price levels in the national currency. Its GDP growth endpoint returns real growth measures. Keep those price bases distinct when building calculations or chart labels.

Work through quarterly and annualised growth

All numbers in this example are illustrative. Suppose a real GDP index rises from 100 in the first quarter to 101 in the second. Quarter-over-quarter growth is (101 / 100 - 1) × 100 = 1%. If the index was 98 in the same quarter a year earlier, year-over-year growth is about 3.06%.

An annualised quarterly rate asks what a quarter's pace would imply if repeated for four quarters. The calculation is ((1 + quarterly rate / 100)^4 - 1) × 100. For the illustrative 1% quarterly increase, the annualised rate is about 4.06%. It is not a forecast or the change already recorded over a full year.

A full-year growth rate compares annual real GDP measures. It need not equal the year-over-year rate in the final quarter. Separately, an annualised GDP level expresses a quarter's output at an annual pace. Do not read that level as the amount produced during the quarter itself.

Align comparisons and expect revisions

Before comparing countries, match the price basis, period, seasonal adjustment, and annualisation. A seasonally adjusted quarterly rate cannot be compared directly with an unadjusted year-over-year rate. Different national currencies also prevent a direct comparison of monetary GDP levels without an explicit conversion method.

Real growth rates avoid a direct currency-level comparison, but they still need matching intervals and conventions. A larger economy can grow more slowly than a smaller one. The size of a GDP level and the speed of its change describe separate things.

Early GDP estimates use incomplete information. Statistics offices revise them as surveys, administrative records, and other inputs become available. Later methodological updates can also change historical estimates. Record the release date with any figure used in a report so readers can understand which release supported the calculation.

Request the level and the growth rate

Use /v1/economics/{country}/gdp for quarterly current-price GDP and /v1/economics/{country}/gdp-growth for quarterly real growth. Both use a period in YYYY-QN format. These requests select the same illustrative US quarter.

Send the API key in the Authorization header. Use the published growth fields for real growth; calculating a percentage change between two current-price GDP values gives a nominal change instead.

curl --request GET \
  --url "https://api.narwhalapi.com/v1/economics/USA/gdp?period=2026-Q2" \
  --header "Authorization: Bearer $NARWHAL_API_KEY"

curl --request GET \
  --url "https://api.narwhalapi.com/v1/economics/USA/gdp-growth?period=2026-Q2" \
  --header "Authorization: Bearer $NARWHAL_API_KEY"

Read the growth response metadata

In this illustrative response, price_basis is constant and annualization is not_annualized. The 0.503% quarter_over_quarter value therefore describes the quarterly change. The 2.4% year_over_year value uses the same quarter a year earlier. Neither value should be relabelled as the other.

The GDP level response has value, currency, price_basis, seasonal_adjustment, and annualization. Its supplied illustrative example uses current prices, USD, and an annualised level. Read each response's metadata independently rather than assuming the level and growth share an annualisation convention.

Growth values are decimal strings in percent. The optional year_to_date field appears only when the official source publishes it. It is absent from this example. Preserve that absence instead of treating it as zero.

{
  "country": "USA",
  "period": "2026-Q2",
  "year_over_year": "2.4",
  "quarter_over_quarter": "0.503",
  "unit": "percent",
  "price_basis": "constant",
  "seasonal_adjustment": "seasonally_adjusted",
  "annualization": "not_annualized",
  "released_on": "2026-07-30"
}

Explore the GDP data pages

Open GDP by country and GDP growth rate by country below to choose between a monetary level and a real growth measure. Use the United States GDP growth rate page for the country view. Keep the response's price basis and annualisation beside the number you display.

The Economics API reference covers request details. “CPI vs inflation rate: how to calculate inflation” explains index levels and percentage changes, including why the comparison period matters.