Inflation rate
Family IX · Macro
Not to be confused with exchange rate, floating exchange rate, interest rate.
Inflation rate is the percentage change in a price index over a period, most often a year. It quantifies how much the general price level has risen (positive) or fallen (negative). Statistical agencies publish it monthly or quarterly, and central banks use it as a primary guide for monetary policy.
Calculation and interpretation
The inflation rate is computed from a price index, such as a consumer price index (CPI) or a wholesale price index. The standard formula is:
Inflation rate = (Indexcurrent − Indexprevious) / Indexprevious × 100
For example, if the CPI rises from 250 to 257.5 over twelve months, the annual inflation rate is (257.5 − 250) / 250 × 100 = 3.0%. A negative result indicates deflation. The choice of index, base year, and coverage (e.g., headline vs. core) affects the reported figure, so comparisons across countries require attention to methodology.
Worked example
Variation and use
Inflation rates vary widely across countries and over time. Central banks often target a specific range, but the target and the preferred index differ by jurisdiction. Investors watch inflation because it erodes purchasing power and influences interest rates, bond yields, and asset valuations. High or volatile inflation can prompt tighter monetary policy, while very low or negative inflation may lead to easing.
Often confused with
- exchange rate
- An exchange rate is the price of one currency in terms of another, whereas an inflation rate measures the change in domestic prices; the visible sign is that an exchange rate is quoted as a currency pair (e.g., EUR/USD) while an inflation rate is a percentage.
- floating exchange rate
- A floating exchange rate is a regime where a currency's value is determined by market supply and demand, not a price change measure; the visible sign is that a floating exchange rate is described as a system, while an inflation rate is a numerical percentage.
- interest rate
- An interest rate is the cost of borrowing or the return on lending, expressed as a percentage of principal, while an inflation rate measures price changes; the visible sign is that an interest rate applies to a loan or deposit, whereas an inflation rate applies to a basket of goods and services.