Diesel Price and Truck Fuel Cost per Mile Reference Table

Truck fuel cost per mile equals diesel price per gallon divided by miles per gallon. At $4.00 per gallon and 6.5 MPG, fuel costs approximately $0.615 per mile, or 61.5 cents per mile.

The table below compares selected diesel-price and fuel-economy assumptions. It is a sensitivity table: it shows how changing either input changes fuel expense. The prices are hypothetical reference points, not current pump prices, and the MPG rows are comparison inputs—not performance benchmarks for a particular truck.

Fuel Cost per Mile by Diesel Price and MPG

All prices are in U.S. dollars per U.S. gallon. MPG means miles per U.S. gallon. Every result in the table is fuel cost in dollars per mile, rounded to three decimal places.

Read across a row to compare diesel prices at the same MPG. Read down a column to compare fuel economy at the same diesel price.

For example, at 6.5 MPG, increasing diesel from $4.00 to $4.50 per gallon raises fuel cost from approximately $0.615 to $0.692 per mile. At $4.00 per gallon, improving fuel economy from 6.0 to 8.0 MPG lowers fuel cost from approximately $0.667 to $0.500 per mile.

Calculate Fuel Cost for Your Own Inputs

Use the formula when your diesel price or MPG falls between—or outside—the values shown:

[
\text{Fuel cost per mile}=\frac{\text{Diesel price per U.S. gallon}}{\text{Miles per U.S. gallon}}
]

For a trip estimate:

[
\text{Trip fuel gallons}=\frac{\text{Total trip miles}}{\text{MPG}}
]

[
\text{Trip fuel cost}=\frac{\text{Total trip miles}}{\text{MPG}}\times\text{Diesel price per gallon}
]

MPG must be greater than zero. Use total miles for the trip being evaluated, including loaded miles and any deadhead miles assigned to that trip. Multiplying by loaded miles alone leaves fuel for the excluded miles out of the estimate.

Keep full precision during the calculation and round the final trip cost to cents. Multiplying a rounded table value by a long distance can produce a different total.

Example: A Trip With Loaded and Deadhead Miles

Assume a hypothetical trip has:

• 1,000 loaded miles.
• 200 deadhead miles.
• 6.5 MPG across the full trip.
• Diesel priced at $4.00 per gallon.

Total trip miles are 1,200. Estimated fuel consumption is:

[
1{,}200\div6.5\approx184.62\text{ gallons}
]

Using the unrounded gallon calculation, estimated trip fuel cost is:

[
(1{,}200\div6.5)\times$4.00=$738.46
]

That is approximately $0.615 per total mile. If you allocate the entire trip’s fuel expense over only the 1,000 loaded miles, it becomes approximately $0.738 per loaded mile. These figures describe the same expense using different mileage denominators; they are not interchangeable.

Choose a Diesel Price and MPG That Match the Trip

Diesel Price

Use a receipt, fuel-card transaction record, or applicable contract price for the fuel being evaluated. Apply discounts consistently, and identify whether separately charged transaction fees are included or tracked elsewhere.

If purchases have different prices, calculate a gallon-weighted average:

[
\text{Average price per gallon}=
\frac{\text{Total diesel purchase dollars}}{\text{Total U.S. gallons purchased}}
]

Do not simply average the posted prices unless the gallons purchased at each price are equal.

For a public planning reference, the U.S. Energy Information Administration publishes U.S. and regional on-highway diesel prices in its Gasoline and Diesel Fuel Update. Those published prices include taxes. Use the observation date and relevant region, and treat the figure as a benchmark rather than a quote for a specific fuel stop or fuel-card account.

The table’s $3.00–$5.00 range does not limit the formula. If your expected price is higher or lower, use that price directly.

Fuel Economy

Use MPG from the same truck and comparable operating conditions when those records are available. Calculate a period’s combined MPG as total miles divided by total gallons consumed, rather than taking a simple average of individual trip MPG figures.

Match the mileage and fuel-consumption periods. Gallons purchased during a short trip may not equal gallons consumed if the truck starts and finishes with different tank levels. Consistent full-to-full records or consumption records that account for tank-level changes provide a more suitable basis.

For planning, choose an MPG assumption that reflects the expected load, route, traffic, weather, and idling. If loaded and deadhead segments have materially different MPG, calculate fuel for each segment separately and add the results:

[
\text{Total gallons}=
\frac{\text{Loaded miles}}{\text{Loaded MPG}}+
\frac{\text{Deadhead miles}}{\text{Deadhead MPG}}
]

If the MPG input already reflects idling fuel, do not add that fuel again. Fuel consumed by a separately fueled refrigeration unit or other equipment needs its own estimate unless it is explicitly included in the consumption input.

Use the Table as a Fuel-Expense Estimate

This calculation estimates diesel expense, not total truck operating cost. It does not add driver compensation, maintenance, tires, insurance, truck payments, tolls, DEF, or other expenses.

It also does not subtract fuel-surcharge revenue. A surcharge affects revenue or cost recovery; it does not change the gallons consumed or the purchase price used here.

When using a tax-inclusive diesel price, the result includes the taxes embedded in that price. The formula does not calculate a separate IFTA balance or reconcile jurisdiction-specific fuel-tax credits and liabilities. Keep any such adjustment separate from the table estimate to avoid confusing fuel purchase expense with a final tax settlement.

For a completed trip, distinguish fuel consumed from fuel purchased. The formula estimates the cost of fuel consumed at the selected price; the cash paid for purchases during that trip can differ when fuel remains in the tanks for later use.