Diesel cost more than regular gasoline per gallon in the latest cited U.S. data. For September 2026, both the Energy Information Administration (EIA) and the Bureau of Transportation Statistics (BTS) put diesel at about $6.29 a gallon, while regular gasoline was about $4.35–$4.36. The difference reflects more than crude oil: distillate demand, refinery economics, lower-sulfur production, taxes, inventories, imports and seasonal use all affect the pump price.
September 2026 U.S. prices: diesel was the more expensive gallon
The comparison below uses the same country and month, but the agencies publish separate statistical series. EIA reports gasoline and diesel averages at slightly different gasoline values than BTS, so it is better to attribute each figure than to blend the series.
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| Source and release | Gasoline measure | Diesel measure | Implied diesel premium |
|---|---|---|---|
| U.S. Energy Information Administration, October 2026 release covering September 2026 | $4.35 per gallon, average retail gasoline | $6.29 per gallon, average retail diesel | $1.94 per gallon |
| Bureau of Transportation Statistics, September 2026 data released October 6, 2026 | $4.36 per gallon, regular gasoline | $6.29 per gallon, No. 2 diesel | $1.93 per gallon |
Using EIA’s figures, diesel was about 45% more expensive per gallon than gasoline (the $1.94 difference divided by $4.35). BTS’s figures imply a nearly identical premium. These are U.S. monthly averages, not a quote for every state, station or day. A local pump can be materially above or below the national average.
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What the two prices actually represent
Regular gasoline versus on-highway diesel
The gasoline comparison is for regular-grade gasoline. The diesel comparison is the on-highway fuel commonly sold as No. 2 diesel. Premium gasoline, biodiesel blends, off-road diesel and heating oil are different products or tax treatments and should not be substituted into this comparison without labeling the change.
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Monthly averages are not today’s price
A September average combines prices observed throughout that month. It will not match a station’s October price, a weekly average or a single transaction. Oil markets, refinery outages, storms, exchange rates, taxes and local competition can move pump prices between the observation date and the day you fill up.
Regional spread matters
BTS reported September 2026 regular-gasoline averages ranging from $3.86 per gallon on the Gulf Coast to $5.54 on the West Coast. That $1.68 regional span is almost as large as the national diesel-versus-gasoline gap. The cited BTS data do not establish a matching regional diesel table here, so it would be misleading to infer one from the gasoline figures. For a household or fleet, the relevant comparison is the price in the vehicle’s actual operating area.
Why diesel can cost more than gasoline
Pump prices are the end result of several layers. EIA identifies crude oil, refining crack spreads, retail margins, distribution costs and taxes as components of diesel pricing. Each can move independently, which is why diesel may remain expensive even after crude oil falls.
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Both fuels begin with crude oil, so a crude-price surge can lift gasoline and diesel together. However, a barrel of crude yields multiple products, and the value of each product depends on demand, refinery configuration and available supply. A crude decline therefore does not guarantee an equal decline at the diesel pump.
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 refinery margin earned from turning crude into diesel. When diesel is scarce relative to crude, the spread can widen and raise wholesale diesel prices. Retail and distribution margins, plus taxes, sit between that wholesale indicator and the amount drivers pay, so a falling crack spread may take time to appear at stations.
Distillate demand is relatively strong
Diesel belongs to the distillate family, which also includes fuel used for heating and other industrial purposes. EIA says demand for diesel and other distillates has been relatively high in Europe, China, India and the United States. When several major markets compete for the same class of fuel, international prices can rise even if U.S. gasoline demand is behaving differently.
Lower-sulfur requirements add production and distribution costs
The U.S. transition to lower-sulfur diesel changed how the fuel is produced and handled. EIA lists the costs associated with making and distributing lower-sulfur diesel as a persistent reason diesel can carry a higher price than regular gasoline. The requirement is a quality and emissions-control issue, but its effect on price comes through refinery processing, logistics and compliance costs.
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EIA’s FAQ lists the federal on-highway diesel excise tax at 24.40 cents per gallon, 6 cents above the federal gasoline excise tax. That difference directly widens the pump-price gap before state and local taxes are added. Tax schedules are policy facts that can change, so verify the current rate when making a long-term budget or comparing states.
International supply affects U.S. diesel
The United States participates in an international market. EIA’s September 2026 analysis attributed current pressure on distillate prices partly to reduced refining activity in Russia, China and the Middle East. Lower overseas production tightened global supply, raised international prices, increased the cost of U.S. imports and encouraged demand for U.S. diesel exports. Those cross-border effects can lift domestic prices even when U.S. production is substantial.
Inventories provide a buffer—and a warning signal
Storage levels influence how comfortably the market can absorb a refinery outage, shipping delay or demand surge. EIA reported U.S. distillate inventories 13% below the 2021–2025 seasonal average for the week ending September 11, 2026. A below-normal cushion makes buyers more sensitive to disruptions and can support a higher diesel crack spread.
Diesel production was still large, but supply was tight
U.S. domestic distillate production averaged 5.1 million barrels per day from January through August 2026, according to EIA. High production does not automatically mean low prices: demand, exports, imports, refinery utilization and inventories determine whether supply is sufficient at the margin. In the cited period, the market remained exposed to tight global conditions despite that production volume.
Seasonal agriculture and heating demand can amplify moves
Farm machinery uses diesel during planting and harvest periods. In the Northeast, heating oil—another distillate—creates additional winter demand. These uses can compete with transportation demand for refinery output and storage. EIA notes that unusually cold winters have occasionally reversed the long-running gasoline-versus-diesel relationship because heating-oil demand can push distillate prices sharply higher.
Why the historical pattern changed after 2004
Diesel was not always the more expensive retail fuel. EIA says on-highway diesel prices have been higher than regular-grade gasoline prices on a dollar-per-gallon basis almost continuously since September 2004. The word “almost” matters: cold winters and elevated heating-oil demand can still produce exceptions.
The post-2004 pattern reflects the combination of stronger global distillate demand, the costs of lower-sulfur diesel and the higher federal diesel excise tax. It is not evidence that diesel must exceed gasoline in every city or every week. Local refinery access, pipeline constraints, seasonal demand and state taxes can temporarily narrow or reverse the difference.
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What EIA expected after September 2026
EIA’s Short-Term Energy Outlook released October 6, 2026 said September prices rose with higher crude-oil prices and rising crack spreads. It forecast distillate prices above $6 per gallon in October, followed by gradual declines, while expecting diesel crack spreads to remain high relative to historical averages.
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For gasoline, EIA expected prices to be roughly unchanged in October before gradually declining. It also expected gasoline crack spreads to remain above seasonal averages into early 2027. These are forecasts, not guaranteed retail outcomes. A forecast for a wholesale spread does not translate one-for-one into a station price because retail margins, distribution costs and taxes intervene.
Does a higher diesel price mean a diesel vehicle costs more to operate?
No. Price per gallon and cost per mile answer different questions. A vehicle’s operating fuel cost depends on both the local price and the vehicle’s actual fuel economy. The cited data do not provide a representative gasoline-and-diesel vehicle pair, so they cannot establish which type is cheaper per mile.
Use this cost-per-mile calculation
- Record the local price per gallon for the exact fuel grade you buy.
- Measure or obtain the vehicle’s fuel economy in miles per gallon for your driving conditions.
- Divide price per gallon by miles per gallon. The result is fuel cost per mile.
- Multiply by the miles you expect to drive to estimate a trip, monthly or annual fuel bill.
For example, the comparison is not “diesel costs $1.94 more, therefore a diesel vehicle costs $1.94 more per mile.” The correct comparison is:
| Vehicle | Formula | Data required |
|---|---|---|
| Gasoline vehicle | Local gasoline price ÷ gasoline vehicle mpg | Actual gasoline price and observed gasoline mpg |
| Diesel vehicle | Local diesel price ÷ diesel vehicle mpg | Actual diesel price and observed diesel mpg |
Use comparable routes, loads, weather and driving behavior. A heavily loaded work vehicle, frequent towing, idling or winter operation can produce fuel economy far from a laboratory label. Fuel cost is also only one ownership expense; purchase price, financing, maintenance, insurance, repairs and resale value require separate data.
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If you know the gasoline vehicle’s mpg and both local prices, you can calculate the diesel vehicle’s break-even mpg:
Diesel break-even mpg = gasoline vehicle mpg × (diesel price ÷ gasoline price).
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- The 2024 ERG guide helps satisfy 49 CFR 172.602 DOT requirement. This requirement states that hazmat shipments be accompanied by emergency response info. Comes with a pack of 10 pocketbooks.
- Pocketbook aids in emergency preparedness, planning, and training with ERGs numerically indexed and color-coded to help emergency responders find vital information fast.
- 2024 Updates: The Pipeline and Hazardous Materials Safety Administration (PHMSA) released a comprehensive summary of updates. Most significantly a QR code on the back cover that provides access to critical incident reporting information.
- Other changes for 2024 have been made to continue to provide the most accurate emergency response information to help all front-line persons and all first responders stay safe during transportation emergencies.
- Specifications: 4" x 5 1/2" Pocketbook Size, English, Spiralbound. Copyright 2024. Comes with a pack of 10 pocketbooks.
At the EIA September averages, the price ratio was $6.29 ÷ $4.35, or about 1.45. A diesel vehicle would therefore need roughly 1.45 times the gasoline vehicle’s fuel economy to match fuel cost per mile under those exact prices. This is a mathematical threshold, not a claim about any particular model. Replace the national averages with your own station prices before using it for a purchase decision.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to compare gasoline and diesel prices for your own budget
Step 1: Match the date and geography
Compare prices from the same day or the same weekly or monthly period, and use the state, metro area or route where the fuel will actually be purchased. A national average can obscure a substantial local tax or supply difference.
Step 2: Match the product
Use regular gasoline against on-highway No. 2 diesel when that is what the vehicles require. Do not compare premium gasoline, off-road diesel or heating oil to on-highway diesel without accounting for the product and tax distinction.
Step 3: Record taxes and fees separately when relevant
For a personal fill-up, the posted pump price is usually the practical number. For a fleet, farm or business, record federal, state and local taxes separately if some are refundable, exempt or treated differently in accounting. The federal diesel-versus-gasoline difference cited by EIA is only one part of the tax picture.
Step 4: Calculate cost per mile from real usage
Use several tanks rather than one unusually efficient or inefficient trip. Separate highway, urban, towing and idling conditions if they represent different work patterns. Then apply the formula above to the miles you actually expect to drive.
Step 5: Check the route before a long trip
Prices can vary by region, especially when a route crosses fuel-tax boundaries or areas served by different refineries and pipelines. Check local fuel prices at departure and along the route, and allow for the vehicle’s usable range. A small detour is not a saving if it adds substantial miles or idling.
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- Mixing months: comparing a current diesel quote with an older gasoline average can manufacture a gap that did not exist at the same time.
- Mixing grades: premium gasoline and regular gasoline are not interchangeable comparison points.
- Treating a national average as a station quote: September’s Gulf Coast and West Coast gasoline averages differed by $1.68 per gallon.
- Assuming a crack-spread change is immediate: retail and distribution margins and taxes delay or soften the pass-through to pumps.
- Using a per-gallon gap as a per-mile result: fuel economy must be included for both vehicles.
- Ignoring non-transport distillate demand: heating oil and agricultural use can tighten the same supply pool as trucking demand.
- Assuming today’s tax is permanent: federal and state fuel taxes are policy variables and should be checked for the period being budgeted.
- Reading a forecast as a promise: EIA’s October outlook describes expected direction, not a guaranteed price at a specific station.
What the September 2026 evidence supports—and what it does not
The evidence supports a clear national answer: diesel was more expensive per gallon than regular gasoline in September 2026, by about $1.93–$1.94. It also supports a structural explanation involving distillate demand, lower-sulfur production and distribution, the higher federal on-highway diesel tax, global supply, inventories, refining margins and seasonal uses.
It does not support a universal claim that every diesel vehicle is more expensive to operate, that diesel will remain above gasoline in every future month, or that one national average applies to every driver. Those conclusions require matched vehicles, local prices, an identified time period and, for ownership decisions, additional cost data.
Bottom line
In the United States, diesel was the costlier fuel per gallon in September 2026: $6.29 versus $4.35 in EIA’s averages and $6.29 versus $4.36 in BTS’s. The premium came from a combination of global distillate demand and constrained supply, refinery crack spreads, lower-sulfur production costs, distribution and retail margins, seasonal uses, inventories and a federal diesel tax that is 6 cents per gallon higher than gasoline’s. To decide whether gasoline or diesel is cheaper for your vehicle, stop at the local pump price and calculate cost per mile using the actual fuel economy of the vehicles you are comparing.
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