A clothing store may not use much fuel in its day-to-day operations, yet a rise in diesel prices can make the clothes it sells more expensive.

Fuel may not be a direct ingredient in the food at the supermarket, but it is used to grow, transport, and store it.

This is one way an energy shock spreads through the economy.

In September 2026, this mechanism was on clear display in the United States, as the Producer Price Index rose 6.3% year over year, its highest reading since December 2022. On a monthly basis, the index jumped 1.3%, compared with 0.5% in August.

What is producer price inflation?

The Producer Price Index, or PPI, measures changes in the prices domestic producers receive for the goods and services they sell.

It is therefore used to understand price pressures arising at different stages of production.

It differs from the Consumer Price Index, which measures the prices people ultimately pay.

But the relationship between the two matters.

If raw materials, transportation, and energy become more expensive for companies, they may try to pass some of the increase on to their customers.

In this way, pressures can start on the producer side and gradually move through the supply chain.

But the pass-through is neither automatic nor complete; a company may absorb some of the cost in lower profits if competition prevents it from raising prices.

Why does fuel have such a big impact?

Because energy is not just a product consumed by individuals; it is a production input used across many sectors.

Trucks need diesel to transport raw materials to factories and products to stores.

Farms use fuel to power equipment and machinery.

Airlines and transportation companies rely directly on energy.

And factories need electricity and fuel for their operations.

In September, energy goods prices in the PPI rose 10.8% in a single month, accounting for more than 80% of the increase in final-demand goods prices, according to the Bureau of Labor Statistics. Diesel and gasoline prices, along with truck freight transportation, were also among the items that pushed up costs at several stages of production.

How does the increase pass through?

Suppose a factory pays 100,000 riyals a month to transport its products.

If its transportation bill rises to 120,000, it has several options.

It may absorb the increase and see its profits fall, try to cut other costs, or raise the price of its finished product.

But the transportation company is also facing higher fuel costs, and the supplier transporting materials to the factory faces the same problem.

So the increase can build up across several stages.

This helps explain why higher energy costs can later show up in the prices of furniture, food, or appliances, even if fuel is not an obvious part of the product.

Why do food prices rise too?

Food is a good example of this pass-through.

Farm produce requires fuel-powered equipment, then it is transported to processing or storage facilities, and from there to distribution centers and stores.

That is why a single increase in energy costs can show up at more than one stage.

In September, producer food prices rose 1.2% in a single month, at the same time as a sharp jump in energy prices.

This does not mean every increase in food prices is caused by fuel, but it shows how energy can add pressure across a broad range of costs.

Why does the central bank care?

The concern is not just a temporary rise in fuel prices.

The more important question is whether the increase will spread to other prices and persist.

If companies raise prices to offset transportation costs, workers then demand higher wages to make up for the cost of living, and companies’ costs rise again, inflation becomes more widespread and harder to bring down.

That is why economists also look at what is known as core inflation.

In September, the Producer Price Index excluding food, energy, and trade services rose 5% from a year earlier, indicating that pressures were not entirely confined to fuel.

Energy doesn’t stop at the gas station

The key takeaway from the inflation data is that energy prices are not just about what drivers pay when they fill up their cars.

The economy is an interconnected network of production, shipping, storage, and sales.

When the cost of an input used across most parts of this network rises, the shock can pass from one company to another until it eventually reaches consumers.

That is why, after oil or diesel prices rise, the question is not just:

How much does fuel cost now?

It is:

How much of the economy will try to pass this cost on to the next stage?

That is where the difference lies between a temporary rise in energy prices and a broader wave of inflation.