What is inflation and how does it work?

Inflation is the sustained increase in the general price level of goods and services in an economy over time. As inflation rises, each unit of currency purchases fewer goods and services — a decline in purchasing power.

How It Is Measured

• CPI (Consumer Price Index): Tracks the average price of a fixed basket of consumer goods and services (food, housing, energy, transportation, etc.).
• PCE (Personal Consumption Expenditures): A broader measure often preferred by central banks (e.g., the U.S. Federal Reserve targets ~2% annually on core PCE).
• Core inflation: Excludes volatile food and energy prices to reveal underlying trends.

Mechanisms That Cause Inflation

1. Demand-pull inflation: Total demand for goods and services exceeds the economy’s productive capacity. “Too much money chasing too few goods.” Often triggered by stimulus spending, low interest rates, or rapid credit expansion.

2. Cost-push inflation: Production costs rise (wages, raw materials, energy, supply chain disruptions), and producers pass costs to consumers. Example: oil price shocks.

3. Built-in inflation (wage-price spiral): Workers expect rising prices and demand higher wages; businesses raise prices to cover labor costs, reinforcing the cycle.

4. Monetary expansion: Increasing the money supply faster than real economic output growth dilutes currency value. This is formalized in the Quantity Theory of Money:

   MV = PQ
   Money Supply × Velocity = Price Level × Real Output

   If M grows faster than Q (output), and V (velocity) is stable, P (prices) must rise.

How It Works in Practice

• Businesses and consumers form inflation expectations; if people expect prices to rise, they act in ways that make it happen (buying sooner, demanding raises, pre-emptive price hikes).
• Inflation compounds: at 5% annual inflation, prices roughly double in ~14 years (Rule of 70: 70 ÷ inflation rate ≈ years to double).

Effects

• Erodes savings held in cash and fixed-income assets.
• Reduces real wages if pay growth lags price growth.
• Benefits borrowers (debts are repaid in cheaper dollars) and hurts lenders/savers.
• Creates uncertainty that discourages long-term investment.
• Hyperinflation (typically >50%/month) can destroy currency confidence entirely (e.g., Weimar Germany 1923, Zimbabwe 2008, Venezuela 2016–2019).

Control Mechanism

Central banks (Federal Reserve, ECB, etc.) combat inflation primarily by raising policy interest rates, which increases borrowing costs, reduces credit demand, slows spending, and cools price growth. The inverse — cutting rates or expanding the money supply (quantitative easing) — stimulates a stagnant economy but risks reigniting inflation. This trade-off is the core of monetary policy.