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Diesel cost more per gallon than regular gasoline in the United States in the latest cited month, September 2026. The U.S. Energy Information Administration (EIA) reported average retail prices of $4.35 per gallon for gasoline and $6.29 for diesel. The Bureau of Transportation Statistics (BTS) reported $4.36 for regular gasoline and $6.29 for No. 2 diesel. That puts diesel $1.94 higher using EIA’s series and $1.93 higher using BTS’s series. The small gasoline difference reflects different agency series, so the figures should not be blended into a single average.
September 2026 prices at a glance
| Source | Gasoline measure | Diesel measure | Implied diesel premium | Period |
|---|---|---|---|---|
| U.S. Energy Information Administration | $4.35 per gallon, average retail gasoline | $6.29 per gallon, average retail diesel | $1.94 per gallon | U.S. monthly average for September 2026, reported in an October 2026 release |
| Bureau of Transportation Statistics | $4.36 per gallon, regular gasoline | $6.29 per gallon, No. 2 diesel | $1.93 per gallon | U.S. monthly average for September 2026, data released October 6, 2026 |
Both agencies therefore support the same practical answer: diesel was more expensive at the pump. These are national monthly averages, not a quote for a particular station. Your price can differ by state, city, fuel grade, taxes, retailer and purchase date.
Why diesel has been more expensive than gasoline
Diesel and gasoline are refined from crude oil, but their prices are set by different balances of demand, refinery output, inventories, transportation and taxes. EIA says on-highway diesel has been priced above regular gasoline on a dollar-per-gallon basis almost continuously since September 2004. That reversed the older pattern in which gasoline commonly cost more. Short-lived exceptions can occur, particularly in cold winters when heating-oil demand places additional pressure on the same broad distillate supply used for diesel.
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Distillate demand is persistent and international
Diesel belongs to the distillate-fuel category, which also includes heating oil and other products. Demand is substantial in freight, construction, farming, mining, power generation and commercial heating. EIA identifies relatively high distillate demand in Europe, China, India and the United States as a structural reason diesel can carry a premium over gasoline. Because these markets compete for internationally traded barrels, a supply problem overseas can affect U.S. wholesale prices even when domestic driving demand has not changed much.
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Lower-sulfur production adds cost and complexity
U.S. on-highway diesel must meet stringent sulfur specifications. EIA lists the costs of producing and distributing lower-sulfur diesel as another long-running factor behind the price relationship. Refineries need suitable equipment, operating time and blending components to meet the specification, and the resulting product must remain segregated through storage and delivery. Those costs are embedded in wholesale and retail margins rather than shown as a separate line on a station sign.
The federal diesel tax is higher
The federal on-highway diesel excise tax is 24.40 cents per gallon, which EIA identifies as 6 cents more than the federal gasoline excise tax. State and local fuel taxes are additional and vary widely. A tax difference does not explain every daily or monthly move—the crude-oil and refining components are usually much larger—but it creates a persistent upward step in the pump price of road diesel. Tax statutes can change, so verify the applicable federal and state rates when making a current budget.
The price chain from crude oil to the pump
A station’s posted price is the end of several linked markets. EIA describes diesel pricing as a combination of crude-oil costs, refining margins (often called crack spreads), retail and distribution margins, taxes and international supply conditions.
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Crude oil
Crude oil is the basic feedstock. When the benchmark price of crude rises, the cost base for both gasoline and diesel generally rises. The pass-through is not one-for-one or instantaneous because refiners, wholesalers and retailers hold inventory purchased at different prices. Crude-quality differences and regional transportation constraints also affect what a refinery actually pays.
Refining margins and the diesel crack spread
EIA defines the diesel crack spread as the wholesale diesel price minus the spot-market price of a gallon of crude oil. It is used as a proxy for the margin available to turn crude into diesel. A widening spread means diesel is becoming more valuable relative to the crude input, often because demand is strong, inventories are tight, or refinery capacity is unavailable. A narrowing spread can reduce wholesale pressure, but the station price may not fall immediately.
Retail, distribution and storage
Fuel travels through pipelines, terminals, tanker trucks and sometimes rail before reaching a station. Each step has operating, financing and loss costs. Retailers also pay for labor, electricity, rent, card processing and compliance. These margins differ by location and business model. A lower wholesale quote therefore does not guarantee an equally large reduction at the pump; EIA specifically warns that retail and distribution margins and taxes separate wholesale estimates from consumer prices.
What is unusual about the September 2026 diesel market?
EIA’s September 2026 analysis points to tight global distillate supply. Refining activity was reduced in Russia, China and the Middle East. Lower overseas production raised international distillate prices, increased the cost of imports into the United States and encouraged demand for U.S. diesel exports. Those forces can lift domestic prices even when U.S. refineries are still producing large volumes.
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Inventory levels
For the week ending September 11, 2026, U.S. distillate inventories were 13% below the 2021–2025 seasonal average, according to EIA. Inventories act as a buffer: when stocks are ample, buyers can absorb a refinery outage or a short demand spike; when stocks are already below normal, the same disruption can produce a larger price response.
Domestic production
U.S. distillate production averaged 5.1 million barrels per day from January through August 2026. That figure describes output, not available surplus. Production can be high while exports, refinery outages, maintenance schedules or stronger domestic consumption keep inventories tight. Supply adequacy depends on the balance among all of those flows.
Seasonal agricultural and heating demand
Diesel use rises with planting and harvest activity in agricultural regions. In the northeastern United States, home-heating oil draws on related distillate supply, especially during cold weather. A seasonal demand surge can therefore affect diesel prices without a comparable change in gasoline consumption.
How large is the September diesel premium?
Using EIA’s figures, the $1.94 diesel difference equals about 45% of the $4.35 gasoline price. Using BTS’s figures, the $1.93 difference is about 44% of the $4.36 gasoline price. The percentage is a useful way to describe the size of the gap, but it is still a monthly national average rather than a prediction for any individual station.
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The dollar effect scales directly with consumption. At the EIA gap, buying 100 gallons of diesel instead of gasoline costs about $194 more; at the BTS gap, it costs about $193 more. A truck, generator or piece of equipment using thousands of gallons would therefore be exposed to a much larger absolute difference than a low-mileage passenger vehicle. Actual savings or costs still depend on the amount purchased, local prices and the vehicle’s measured fuel use.
Regional prices can differ more than the national gasoline gap
National averages conceal large geographic spreads. BTS reported September 2026 regular-gasoline averages ranging from $3.86 per gallon on the Gulf Coast to $5.54 on the West Coast—a $1.68 regional difference within gasoline alone. The comparison reflects differences in refinery concentration, pipeline access, maritime supply, environmental specifications, local taxes and retail competition.
Do not use a national gasoline average with a local diesel quote, or a Gulf Coast figure with a West Coast figure, to calculate a personal fuel premium. Match the same place, grade and date. Diesel regional values were not established in the cited BTS figures, so no diesel regional ranking should be inferred from the gasoline range.
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Does a higher price per gallon mean diesel costs more to drive?
No. A pump-price comparison answers the cost of one gallon; it does not answer the cost of moving a vehicle one mile. Diesel vehicles often have different fuel economy, engine sizes, payloads, transmissions and duty cycles than gasoline vehicles. Those variables must be measured rather than assumed.
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For each vehicle, calculate:
fuel cost per mile = local price per gallon ÷ verified miles per gallon
Use the fuel price you can actually buy, not a national headline average. Use fuel economy measured for the same vehicle, load, route and season. If a vehicle’s fuel economy is reported in miles per gallon, divide the price by that value. For a fleet, calculate separately for highway, urban, idling and loaded operation, then weight the results by the miles actually driven.
Include the costs that fuel economy leaves out
- Purchase and financing: A vehicle that saves fuel may cost more upfront or carry different financing costs.
- Maintenance: Service intervals, oil capacity, emissions hardware and repair prices differ by engine and vehicle.
- Payload and towing: A vehicle’s useful work may matter more than an unloaded test-mile figure.
- Depreciation and insurance: These can outweigh a modest fuel-price difference over the ownership period.
- Idling and short trips: Real-world use can depart sharply from an advertised or laboratory fuel-economy rating.
The September 2026 price data do not establish a representative gasoline-versus-diesel vehicle pair, so they cannot support a universal claim that either fuel is cheaper per mile.
Who is most exposed to a diesel premium?
High-use operators feel a per-gallon difference fastest because fuel is a major recurring purchase. Freight carriers, construction companies, farms, mining operations, generators and commercial-heating users can consume far more distillate than a typical passenger driver. Their budgets should track both gallons and operating hours, since idling and heavy loads can raise consumption without adding road miles.
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How to compare your own fuel bill
- Define the comparison. Choose the same driving period, route mix, vehicle load and fuel grade. Decide whether you are comparing a personal car, a pickup, a van or commercial equipment.
- Record local prices. Note the posted price, station location, date and whether the price includes a loyalty discount or other conditional reduction.
- Measure consumption. Track gallons and miles over several fill-ups. A single tank can be distorted by a partial fill, unusual traffic, weather or a different route.
- Calculate fuel cost per mile. Divide the money spent on fuel by miles driven, or divide the matched price per gallon by measured miles per gallon.
- Add ownership costs. Compare maintenance, tires, insurance, financing and depreciation over the period you expect to keep the vehicle.
- Stress-test the result. Recalculate with a higher and lower local fuel price, winter conditions, a heavier load and the possibility of extended idling.
This method produces a decision for your use case rather than a generalization from national averages.
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How to read fuel-price statistics correctly
Match the grade and product
“Gasoline” can refer to a regular-grade average or a broader retail series. “Diesel” can refer to No. 2 diesel or on-highway diesel. Premium gasoline, off-road diesel and heating oil are different products or tax treatments. Read the agency label before subtracting one number from another.
Match the time basis
A weekly average can move differently from a monthly average during a fast price change. The September 2026 figures above are monthly averages. Do not compare them with a single day’s station sign and describe the result as a monthly premium.
Keep agency series separate
EIA and BTS both reported diesel at $6.29 per gallon for September 2026, while their gasoline figures differed by one cent. That is normal for independently constructed series. Attribute each figure to its agency and calculate the gap within that series instead of averaging the two gasoline numbers.
Separate wholesale signals from retail outcomes
Crack spreads and inventory reports help explain pressure in the supply chain, but they are not pump prices. Taxes, transportation, station margins and inventory purchased earlier can delay or soften the retail response.
What the October 2026 outlook says—and what it does not
EIA’s Short-Term Energy Outlook released October 6, 2026, projected distillate prices above $6 per gallon in October, followed by gradual declines. It expected diesel crack spreads to remain high compared with historical averages. For gasoline, EIA projected roughly unchanged prices in October before gradual declines, with gasoline crack spreads staying above seasonal averages into early 2027.
Those are forecasts, not guaranteed prices. They depend on crude-oil markets, refinery operations, international trade, weather, inventories and policy. A forecasted wholesale decline may reach consumers slowly because retail and distribution margins and taxes intervene between the refinery and the pump. Recheck current EIA or BTS data before making a purchase, route or fleet decision.
Common mistakes when asking which fuel costs more
- Using efficiency as proof: Better miles per gallon do not automatically overcome a large price-per-gallon premium.
- Using pump price as proof of per-mile cost: The vehicle’s measured fuel economy is required.
- Mixing locations: A Gulf Coast gasoline price and a West Coast diesel price do not form a valid comparison.
- Mixing products: Regular gasoline, premium gasoline, No. 2 diesel, off-road diesel and heating oil have different specifications and taxes.
- Treating a forecast as a fact: Outlook figures describe expected conditions, not a guaranteed station price.
- Ignoring tax treatment: On-highway and off-road diesel can have different tax rules, and state taxes vary.
- Expecting instant pass-through: Retail inventories and distribution margins can delay changes in crude or crack-spread prices.
Bottom line for U.S. drivers and operators
In September 2026, diesel was the more expensive fuel per gallon in both major U.S. series cited here, by roughly $1.93–$1.94. Its premium reflects sustained distillate demand, lower-sulfur production and distribution requirements, a higher federal on-highway tax, and current pressure from tight global supplies and below-normal inventories. Whether gasoline or diesel is cheaper for your vehicle still requires local prices, measured fuel economy and the full ownership cost—not the pump-price gap alone.
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Frequently Asked Questions
Which fuel was more expensive in the United States in September 2026?
Diesel. EIA reported $6.29 per gallon for diesel versus $4.35 for gasoline, a $1.94 gap. BTS reported $6.29 for No. 2 diesel and $4.36 for regular gasoline, a $1.93 gap.
Why has diesel usually cost more than gasoline since 2004?
EIA says diesel has been more expensive on a dollar-per-gallon basis almost continuously since September 2004 because of relatively high distillate demand, the costs of producing and distributing lower-sulfur diesel, and a federal on-highway diesel tax that is 6 cents per gallon higher than gasoline’s.
Does diesel cost more per mile than gasoline?
The pump-price data alone cannot answer that. Divide each local fuel price by the matched vehicle’s verified miles per gallon, then consider maintenance, financing, depreciation, insurance, payload and idling.
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It is the wholesale diesel price minus the spot-market price of a gallon of crude oil. EIA uses it as a proxy for the refining margin available to turn crude into diesel.
Why can diesel prices rise when U.S. production is high?
High output does not guarantee a surplus. Exports, refinery outages, maintenance, domestic demand and international prices can keep inventories tight. U.S. distillate inventories were 13% below the 2021–2025 seasonal average for the week ending September 11, 2026, despite average production of 5.1 million barrels per day from January through August.
How much does the federal diesel tax add?
EIA lists the federal on-highway diesel excise tax at 24.40 cents per gallon, 6 cents more than the federal gasoline excise tax. State and local taxes are separate and vary by location.
Will a lower crude price immediately lower the pump price?
Not necessarily. Retail and distribution margins, taxes and fuel purchased earlier can delay or reduce the pass-through from crude or wholesale crack-spread changes to station prices.
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Bottom line: Diesel cost about $1.93–$1.94 more per gallon than gasoline in the September 2026 U.S. averages. The right per-mile choice depends on your local prices, measured fuel economy, usage and total ownership costs.
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