US inflation rises more than expected - here's what is happening with prices

US inflation accelerated in September, reaching 3.7% over the previous 12 months. That was higher than the 3.4% recorded in the year to August and above economists’ forecasts. The release was closely watched because it came just before the US midterm elections, when cost-of-living pressures were a major issue.

Gasoline was the biggest immediate driver. Car fuel prices rose 34.2% over the year and jumped 9.1% during September alone. That monthly increase accounted for more than half of the overall rise in inflation, according to the Bureau of Labor Statistics.

The figures show that energy shocks can quickly lift the headline inflation rate. Food prices were relatively calm, rising 2.5% over the year, while core inflation was 2.6% after excluding food and energy. The Federal Reserve will watch whether high energy costs spread into other prices.

Inflation measures how quickly the prices of products and services increase. A 3.7% annual inflation rate does not mean every item became 3.7% more expensive. It describes the average change across the consumer basket tracked by the Bureau of Labor Statistics.

For example, the article uses milk to explain the idea. If a bottle costs $1 and rises to $1.10 a year later, milk inflation is 10%. In the latest figures, gasoline rose much faster than many other categories, while food inflation was 2.5% over the year.

Therefore, people experience inflation differently depending on what they buy. Overall, the September rate means the measured basket cost more than it did a year earlier. Prices can still rise even when inflation later slows, because a slower increase is not the same as a price decline.

Energy prices drove September’s inflation increase. Car fuel prices rose 34.2% over the year and climbed 9.1% in September alone. That one-month jump contributed more than half of the total increase in inflation, making gasoline the clearest source of pressure.

Energy inflation overall rose 20.4% over 12 months. The measure includes gasoline, fuel oil, energy services, and electricity. Fuel oil, which is used for home heating, recorded the largest increase among the examples given, rising 74.2% over the year.

Other prices were less intense. Food inflation was flat in September and 2.5% over the year. Core inflation, which removes food and energy, was 2.6%. The Federal Reserve will examine whether energy costs begin feeding into other parts of the economy, including food prices.

Crude oil sits at the start of the fuel supply chain. Gasoline and diesel are made from it, so when less crude is available while demand stays steady, suppliers can charge more. That higher input cost can then reach drivers through higher prices at the pump.

The article gives a clear example. Crude oil traded at just over $70 a barrel before the US-Israel war with Iran began. When the conflict constricted crude supplies, its price quickly rose and reached more than $100 a barrel. Gasoline prices subsequently became a major source of US inflation.

This mechanism explains why an overseas energy disruption can affect household budgets at home. In September, car fuel prices rose 9.1% in one month and 34.2% over the year. The Federal Reserve is watching whether this energy shock spreads to food and other prices.

The Consumer Price Index, or CPI, measures inflation by tracking how prices change across a broad group of goods and services. The Bureau of Labor Statistics uses it to estimate the overall price level in the US economy. This gives officials a common measure instead of relying on one product’s price.

The CPI follows hundreds of everyday items. Its basket includes fresh food, gasoline, and medical services. If gasoline rises sharply while some other prices stay stable, the combined movements help show how prices are changing overall. The September inflation figures were based on this kind of broad measurement.

The basket is updated over time because people’s spending and lifestyles change. Including current purchasing patterns makes the index more useful for judging household cost pressures. It also helps policymakers, including the Federal Reserve, assess whether inflation is moving above its 2% target.

Tariffs are levies businesses pay on imported goods. When tariffs rise, US companies usually face higher costs for the products they buy from overseas. They may pass those costs on through higher prices, affecting consumers who purchase imported goods or products made with imported inputs.

The New York Fed found exporters reduced their prices very little after the new tariffs. As a result, US-based businesses absorbed nearly 90% of the added tax. Tariffs also affected locally made goods because many US producers depend on overseas parts or materials. Those higher production costs can lift domestic prices too.

The overall effect was measurable. The Fed found that each one-percentage-point increase in average tariffs led to nearly a 0.25% increase in consumer-goods prices after one year. This adds inflation pressure even when the final product is made in the United States.

Inflation is a rate of change, not a measure of whether prices are high or low. If prices rise 3% one year and 2% the next, inflation has slowed, but prices have still increased in both years. Prices generally fall only when there is deflation, which is different from a lower inflation rate.

The article gives a simple milk example: a $1 bottle rising to $1.10 represents 10% inflation. If it later rises more slowly, the bottle can still cost more than $1. The same idea applies to the wider CPI basket, which includes food, fuel, and services.

The Federal Reserve’s target is 2%, so September’s 3.7% rate remains above its preferred level. The article does not explain the target’s broader rationale, but a lower, steadier rate is generally intended to keep price increases manageable. Energy costs could complicate that goal if they spread elsewhere.