What this calculator does
The GDP deflator formula divides nominal GDP by real GDP and multiplies by 100. Nominal GDP measures output at current prices, while real GDP measures the same output at the prices of a chosen base period, so the ratio between them isolates how much of the change in nominal GDP came from prices rising rather than from more goods and services actually being produced.
A GDP deflator of 100 means prices have not moved since the base period. A reading of 112 means the general price level across the whole economy is 12% higher than in that base year. Unlike the consumer price index, which tracks a fixed basket of household goods, the GDP deflator covers every good and service counted in GDP, including investment, government spending and exports, so it shifts as the mix of the economy changes as well as when prices do.
The formula
Divide nominal GDP by real GDP, then multiply by 100. The result above 100 shows prices have risen since the base period; below 100 means prices have fallen. Subtracting 100 from the deflator gives the implied percentage price change directly.
| Term | Meaning |
|---|---|
| Nominal GDP | Total output valued at current-year prices. |
| Real GDP | The same output valued at base-period prices, stripping out price changes. |
| GDP deflator | (Nominal GDP ÷ Real GDP) × 100, an index of the economy-wide price level. |
The inputs explained
| Field | What to enter |
|---|---|
| Nominal GDP ($B) | Total GDP measured at current prices for the period you are checking. |
| Real GDP ($B) | The same period’s GDP restated in constant, base-period prices. |
When to use it
Working out how to calculate GDP deflator from published figures
Statistical agencies publish both nominal and real GDP each quarter. Dividing one by the other and multiplying by 100 turns those two series into a single price-level index without needing any other data.
Separating price growth from real growth
If nominal GDP rose 8% but real GDP only rose 3%, the deflator shows how much of that 8% was simply prices increasing rather than the economy actually producing more.
Comparing broad inflation measures
Because the deflator covers all domestically produced goods and services, comparing it against the consumer price index over the same period shows whether inflation is concentrated in household spending or spread more widely across investment and government activity too.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the GDP deflator changes as nominal GDP rises at a fixed real GDP
A fixed $24,000B in real output, against a range of nominal GDP figures.
| Nominal GDP | GDP deflator | Implied price change vs base period |
|---|---|---|
| $24,000B | 100.00 | +0.00% |
| $25,000B | 104.17 | +4.17% |
| $26,000B | 108.33 | +8.33% |
| $27,000B | 112.50 | +12.50% |
| $28,800B | 120.00 | +20.00% |
| $30,000B | 125.00 | +25.00% |
How the GDP deflator changes as real GDP rises at a fixed nominal GDP
A fixed $27,000B in current-price output, against a range of real GDP figures.
| Real GDP | GDP deflator | Implied price change vs base period |
|---|---|---|
| $22,000B | 122.73 | +22.73% |
| $23,000B | 117.39 | +17.39% |
| $24,000B | 112.50 | +12.50% |
| $25,000B | 108.00 | +8.00% |
| $26,000B | 103.85 | +3.85% |
| $27,000B | 100.00 | +0.00% |
Questions
How do you calculate the GDP deflator?
Divide nominal GDP by real GDP for the same period, then multiply by 100. Both figures need to cover the same geography and time period for the ratio to mean anything.
What is a GDP deflator calculator actually showing?
It converts two GDP figures, one at current prices and one at base-period prices, into a single index number that represents the overall price level of everything counted in GDP, relative to that base period.
How is the GDP deflator different from the consumer price index?
The CPI tracks a fixed basket of goods and services that households buy. The GDP deflator covers the prices of everything produced domestically, including capital goods, government purchases and exports, and its basket implicitly changes as the composition of the economy changes.
Can the GDP deflator fall below 100?
Yes, if the base period is a later or higher-price year than the one being measured, or during a period of falling prices (deflation) relative to the base period. A reading below 100 simply means the overall price level was lower than in the base period.
For a related measure of economic output relative to population, see the GDP per capita calculator.