Inflation: Why Prices Rise and How We Measure It

Inflation is a sustained rise in the general price level across the economy, and it can come from a few genuinely different underlying causes.

A single price rising - gasoline getting more expensive one month - isn’t inflation. Inflation describes something broader: a sustained increase in the general price level across the economy as a whole, meaning a given amount of money buys measurably less than it used to across a wide range of goods and services.

What counts as inflation, and what doesn’t

It’s worth being precise here. If one good’s price rises while others fall or stay flat, that’s a relative price change, not inflation - and relative price changes happen constantly for all sorts of ordinary reasons, like a poor harvest raising the price of one crop specifically. Inflation refers specifically to a broad, sustained rise across the general price level, not a one-time jump in a single product’s price. It’s typically measured using the Consumer Price Index, covered in detail in a later lesson in this module.

Two broad causes of inflation

Demand-pull inflation happens when overall demand across the economy grows faster than the economy’s ability to produce goods and services to meet it - too much total spending chasing a relatively fixed amount of output, pulling prices up broadly. This connects directly to aggregate demand, covered in the lesson later in this module on aggregate supply and demand.

Cost-push inflation happens when the cost of producing goods and services rises broadly across the economy - a sharp, widespread increase in energy prices or wages, for instance - pushing businesses to raise prices to cover their higher costs, even without any increase in overall demand. This connects to the aggregate supply side of that same later lesson.

Two very different roads to the same 5% inflation rate

Imagine two different economies both experiencing 5% inflation in a given year. In the first, a booming economy with low unemployment and strong consumer spending is simply generating more total demand than businesses can immediately supply, pulling prices up - demand-pull inflation. In the second, a spike in global energy prices is raising costs for nearly every business that relies on transportation or manufacturing, forcing them to raise prices even as demand stays flat - cost-push inflation. Both economies show the same headline inflation number, but the underlying cause, and the appropriate policy response, are genuinely different.

Why moderate inflation is treated differently from severe inflation

Assuming all inflation is equally harmful

It's tempting to treat any inflation as straightforwardly bad, but most economists actually target a low, stable, positive rate of inflation - often around 2% annually in many countries - rather than zero. A small amount of predictable inflation gives central banks room to lower real interest rates during downturns, and it avoids the specific problems associated with falling prices generally, called deflation, which can discourage spending as consumers wait for prices to fall further. The real economic concern is usually inflation that is high, volatile, or unpredictable - not the mere existence of a small, steady, well-anticipated rate of inflation.

Why inflation is one of the most closely watched numbers in economics

Inflation affects nearly everyone directly, eroding the purchasing power of savings and fixed incomes if it runs ahead of wage growth, and it’s one of the primary targets central banks manage through monetary policy, covered in this curriculum’s banking and money basics modules. Understanding its causes is essential background for the next several lessons in this module, including the business cycle, the Consumer Price Index, and stagflation - a particularly difficult combination covered in a dedicated lesson later in this module.

Key takeaways

Inflation is a sustained rise in the general price level across the economy, distinct from a single good's price rising.
Demand-pull inflation occurs when total demand outpaces the economy's ability to produce.
Cost-push inflation occurs when broad increases in production costs push businesses to raise prices.
Most economists target a low, stable, positive inflation rate rather than zero inflation.
The real concern is usually inflation that is high, volatile, or unpredictable, not moderate, steady inflation.