What is inflation?

What does inflation actually mean?

Inflation is not one price going up. A pricier phone or a bad harvest that lifts coffee prices is a relative price change. Inflation is the broad drift upward in the prices of most things people buy, so that the same amount of money covers less than it used to. The European Central Bank puts it simply: with inflation, one euro buys less today than it did yesterday.

The flip side of rising prices is falling purchasing power. If prices rise 3% in a year, $100 at the end of that year buys roughly what $97 bought at the start. That is why inflation matters to anyone holding cash, receiving a fixed pension or comparing the interest on a savings account. You can test your own numbers with our inflation calculator.

When prices fall across the board, the opposite happens. The IMF notes that this deflation can lead people to delay purchases, which tends to weigh on growth — one reason central banks aim for low positive inflation rather than zero or negative.

How is inflation measured?

Statistics agencies track the price of a fixed basket of goods and services that represents what typical households buy, and then calculate how much that basket's cost changes over time.

1. Collect prices. In the US, Bureau of Labor Statistics (BLS) staff record the prices of about 80,000 items every month in stores, service businesses and online.

2. Weight them. Items count in proportion to how much households spend on them, so a big monthly expense moves the index far more than a minor one.

3. Build an index. Most CPI series are set so that the average of 1982–84 equals 100. An index of 310 means the basket costs 3.1 times what it did then.

4. Compare over time. The inflation rate is the percentage change in the index, usually versus the same month a year earlier.

The euro area does the same with the HICP, which Eurostat compiles from national price data and weights each country by its share of euro area consumer spending.

Which inflation measures should you know?

Several indexes exist because they answer slightly different questions. The headline number in the news is usually the first one in the table.

In August 2026, US headline CPI rose 3.4% over twelve months while core CPI rose 2.4%. Most of the gap reflects energy, whose index was up 16.3% — a reminder of why analysts look at core measures alongside the headline.

What causes inflation?

There is no single cause, and economists still argue about how much each factor matters in a given episode. The IMF's introductory guide groups the usual suspects like this:

• Demand-pull. Spending grows faster than the economy can produce, so sellers can raise prices.
• Cost-push. Production costs jump — energy, raw materials, supply disruptions — and firms pass them on.
• Expectations. If people expect higher prices, they ask for higher wages and write price rises into contracts, which can make inflation self-reinforcing.
• Money growth. Too much money chasing the same output can erode the value of each unit of currency.

Central banks mainly respond through interest rates. The Federal Reserve explains that its policy rate influences other borrowing costs, spending and hiring, with effects that are neither direct nor immediate. We explain the knock-on effects for investors in how interest rates affect stocks, bonds and crypto.

Who wins and who loses from inflation?

Inflation redistributes purchasing power. According to the IMF, people whose wages lag behind prices and retirees on fixed payments lose ground, while borrowers on fixed-rate loans can gain, because they repay with money that is worth less.

For savers, the key figure is the real return: the interest rate minus inflation. A savings account paying 1.5% while prices rise 3.4% leaves you about 1.8% poorer in purchasing power over the year (1.015 ÷ 1.034 − 1 ≈ −1.84%), even though the balance went up. Over long periods the effect compounds: at a steady 3% a year, prices rise by about 34% in a decade. Our compound interest calculator shows the same math working in the other direction.

Some people buy crypto-assets because of inflation fears. Bitcoin's software caps its supply at 21 million coins, as explained in what is bitcoin, but a fixed supply does not make a price stable: the SEC's chair described bitcoin in 2024 as primarily a speculative, volatile asset. Stablecoins pegged to the dollar simply inherit dollar inflation — see what is a stablecoin.

What mistakes do people make when reading inflation numbers?

• Confusing the inflation rate with the price level. Inflation falling from 4% to 3% means prices are still rising, just more slowly. It does not mean prices are going back down.
• Mixing monthly and yearly figures. The 0.4% rise in US CPI for August 2026 is a one-month, seasonally adjusted change; the 3.4% figure covers twelve months.
• Comparing different indexes. US CPI, US PCE and euro area HICP use different baskets and methods. Compare like with like.
• Ignoring the date. A new inflation figure replaces the last one every month. Always check the reference month — the BLS publishes September 2026 CPI on 14 October 2026.
• Treating your nominal balance as your wealth. What matters is what the money can buy.