3 things to know about rising diesel prices and how they affect you

Diesel prices have reached historic highs as a result of the U.S. war in Iran and Russia's war in Ukraine, and consumers will bear the brunt of the rising cost, experts say.

As of Wednesday, the national average for a gallon of diesel was $6.52, according to AAA. That's up from an average of $3.69 this time last year.

"The average person, including myself, doesn't typically buy diesel fuel," said Kenneth Gillingham, professor of environmental and energy economics at Yale University. "But diesel fuel is crucial for so many parts of our economy."

Energy and economics experts who spoke with PBS News said Americans can expect higher costs across the board as a result of the record high diesel prices, at a time when consumers are already struggling with stubborn inflation.

In August, while diesel prices were nearly $1 cheaper than they are today, consumer prices rose by 3.4% compared to a year ago, according to a Labor Department report.

WATCH: News Wrap: August inflation report shows consumer prices up 3.4%

Here's what to know about diesel prices, which industries rely on the fuel and how rising costs are expected to be passed down to consumers.

Why are diesel prices so high, and why are they expected to remain that way for a while?

Ongoing global conflicts have led to rising prices across multiple industries, and the cost of diesel is no different.

However, diesel is "suffering from a two-pronged attack," Gregory DeYong, a professor at Southern Illinois University and expert in supply chain management, said in an email.

The U.S. war in Iran has affected the supply of crude oil, from which diesel is produced. In early September, the price of a barrel of oil again surpassed $100. The effective closure of the Strait of Hormuz, a major shipping route for the world's oil, and the bombing of oil facilities and alternate shipping routes in Saudi Arabia have contributed to the rise.

WATCH: Iran-backed Houthis seize island at entrance to Red Sea, threatening Saudi oil exports

Diesel supply has also been affected by the loss of refineries in Russia amid its war with Ukraine. Russian oil facilities, including refineries that produce diesel, have been hit by Ukrainian strikes, straining the industry.

After the U.S. and China, Russia has been the third-largest producer of refined oil products in the world, according to a September International Energy Agency report. In June, the amount of oil going through Russia's refineries dropped to its lowest levels in more than 20 years, the report found.

Even though an end to the global wars would ease the strain on the oil market, it wouldn't immediately solve the rising costs, experts said.

WATCH: Trump says oil prices will come down after midterm elections

Repairing and building refineries takes several months to years to complete. And existing refineries are already running near capacity. In the U.S., refineries were running at 97% capacity as of Sept. 11, according to the U.S. Energy Information Administration.

"It will still take some time for prices to come back down, simply because inventories will have to be rebuilt, refineries will have to be put back up and running, and the standard flow of trade would have to be reestablished," Gillingham said.

What runs on diesel?

Even though fewer than 3% of passenger cars in the U.S. run on diesel, much of the economy does.

"Diesel is the fuel that moves the economy," Patrick De Haan, head of petroleum analysis at GasBuddy, said in a statement.

Some of the industries that rely on diesel include:

• Shipping and logistics: Most vehicles used in transporting stuff to and within the U.S. — such as trucks, trains and large boats — run on diesel. This includes trucks that transport gasoline to gas stations.
• Home heating: About 4.8 million homes in the U.S., mainly in the Northeast, use heating oil in the winter as their primary heating fuel, according to the Energy Information Administration. Heating oil is "essentially identical to diesel fuel," DeYong said.
• Agriculture: Heavy machinery used in agriculture, irrigation pumps used on fields and trucks that transport food from farms to stores rely on diesel. Many fertilizers and chemicals that farmers use on crops are also petroleum-based. "Every part of the food system uses diesel," said Jeffrey Dorfman, a professor of agricultural and resource economics at North Carolina State University.
• Construction: Trucks that deliver construction material to worksites run on diesel, as do the heavy machinery used to carry out "demanding construction work, such as lifting steel beams, digging foundations and trenches, drilling wells, paving roads, and moving soil and rocks," according to the Energy Information Administration.

A worker fills his truck with diesel fuel at a corporate filling station in San Diego, California, May 18, 2026. Photo by Mike Blake/Reuters

How are diesel prices passed down to consumers?

Because so much of the economy relies on diesel, the rising cost of the fuel will lead to further increased costs for consumers. But how much or how quickly prices will rise vary based on the product and the industry.

"High diesel prices primarily affect consumers indirectly, as firms along the supply chain make decisions about whether to absorb higher diesel prices or pass these along to their buyers," Jason Miller, supply chain management professor at Michigan State University, said in an email.

Since most businesses rely on diesel to transport their goods, a rise in the cost of diesel will affect the product's final price. For example, the cost of truck transportation has increased by about 14% since January, according to the Federal Reserve Economic Data website.

Retail shipping companies like UPS, Amazon and FedEx have implemented fuel surcharges.

The effects of rising diesel costs "are already in the store and they are going to be even more obvious in the next few months," Dorfman said.

Even though many businesses rely on diesel in some way, they don't all equally pass the price down to consumers.

Factors that affect how quickly and by how much a product's price will increase include:

• How much of a product's final price relies on the cost of transportation: Prices are more likely to increase for products for which transportation expenses represent a larger share of their final cost. For example, the price of food products that are shipped across the U.S. versus those that are locally grown will be affected differently.
• A product's shelf life: Products with longer shelf lives like flour or olive oil were likely transported to stores before the cost of diesel skyrocketed. Therefore, it may take longer for consumers to see a rise in the price of those products. On the contrary, retailers of fresh produce are currently having to make decisions about how and whether to pass on the higher fuel costs to consumers, Miller said.
• Businesses' perception of diesel price hikes: Business leaders have mixed perceptions of how long diesel prices will stay elevated. Companies that see the increase in diesel costs as long-term are raising prices, whereas those that believe the price hikes are temporary are absorbing the increases without passing them down to consumers, Miller said.