# What is the GDP deflator?

Computes the GDP deflator from nominal and real GDP (nominal ÷ real × 100), or real or nominal GDP from the deflator, with the inflation rate between two years.

- Page: https://www.acalculator.org/finance/gdp-deflator-calculator
- JSON spec: https://www.acalculator.org/finance/gdp-deflator-calculator.json
- Version: e65d02ba7537

## Default answer

Example with the default inputs (Find Deflator, Nominal GDP 18,206, Real GDP 17,388.7): The GDP deflator is 104.7; real GDP is 17,388.7 and nominal GDP is 18,206.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| find | Find | Which of the three to work out from the other two. |
| nom | Nominal GDP | GDP at the prices of its own year, in any unit (such as billions of dollars). |
| real | Real GDP | GDP at base-year prices, in the same unit as nominal GDP. |
| defl | GDP deflator | The GDP price index, with the base year = 100. |
| prev | Deflator in an earlier year | Optional: an earlier year’s deflator, to get the inflation rate between the two years. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| deflatorOut | GDP deflator | Nominal GDP ÷ real GDP × 100. |
| realOut | Real GDP | Nominal GDP ÷ (deflator ÷ 100), in the unit you typed. |
| nominalOut | Nominal GDP | Real GDP × deflator ÷ 100, in the unit you typed. |
| priceChange | Price level change since the base year | Deflator − 100: the percent change in prices since the base year. |
| inflation | Inflation since the earlier year | (Deflator ÷ earlier deflator − 1) × 100. |

## Method

Deflator = nominal GDP ÷ real GDP × 100; real GDP = nominal GDP ÷ (deflator ÷ 100); nominal GDP = real GDP × deflator ÷ 100; inflation = (deflator ÷ earlier deflator − 1) × 100.

## Assumptions

- The deflator is a price index with the base year = 100, as in the US national accounts.
- Nominal and real GDP are in the same unit; you type every number, and no data is looked up.

## Worked examples

1. find = deflator, nom = 18,206, real = 17,388.7 gives deflatorOut = 104.700179, priceChange = 4.700179%. Source: https://openstax.org/books/principles-macroeconomics-3e/pages/6-2-adjusting-nominal-values-to-real-values.
2. find = real, nom = 542.4, defl = 16.6 gives realOut = 3,267.46988. Source: https://openstax.org/books/principles-macroeconomics-3e/pages/6-2-adjusting-nominal-values-to-real-values.
3. find = nominal, real = 16,254, defl = 100 gives nominalOut = 16,254, priceChange = 0%. Source: https://openstax.org/books/principles-macroeconomics-3e/pages/6-2-adjusting-nominal-values-to-real-values.
4. find = deflator, nom = 20,893.7, real = 18,392.3, prev = 104.7 gives deflatorOut = 113.600257, inflation = 8.500723%. Source: https://openstax.org/books/principles-macroeconomics-3e/pages/6-2-adjusting-nominal-values-to-real-values.

## FAQ

### How do I calculate the GDP deflator?

Divide nominal GDP by real GDP and multiply by 100. For the United States in 2015: $18,206.0 billion ÷ $17,388.7 billion × 100 = 104.7, so prices were 4.7% higher than in the 2012 base year.

### How do I find real GDP from the deflator?

Divide nominal GDP by the deflator over 100. In 1960, nominal GDP was $542.4 billion and the deflator was 16.6: $542.4 billion ÷ 0.166 = $3,267.5 billion in 2012 dollars.

### What is the difference between nominal and real GDP?

Nominal GDP values each year’s output at that year’s prices. Real GDP values it at the prices of a base year, so it changes only when the quantity of goods and services changes. In the base year the two are equal and the deflator is 100.

### How do I calculate inflation from the GDP deflator?

Take the percent change between two years’ deflators: (later ÷ earlier − 1) × 100. From 104.7 in 2015 to 113.6 in 2020 is (113.6 ÷ 104.7 − 1) × 100 = 8.5% over the five years.

### How is the GDP deflator different from the CPI?

The GDP deflator covers every good and service produced in the country, including investment and government purchases. The consumer price index covers a basket of goods and services that households buy, including imports.

### Where do I find nominal and real GDP?

In the national accounts. For the United States, the Bureau of Economic Analysis publishes GDP in current dollars and in chained dollars, and the implicit price deflator. Type the numbers here; the page looks nothing up.

## Sources

- OpenStax. Principles of Macroeconomics 3e, §6.2 Adjusting Nominal Values to Real Values (deflator = nominal ÷ real × 100; table of US nominal GDP, deflator and real GDP, 1960 to 2020, base year 2012), retrieved 2026-10-18. https://openstax.org/books/principles-macroeconomics-3e/pages/6-2-adjusting-nominal-values-to-real-values