Knowing how to calculate a fuel surcharge helps shippers understand why transportation costs change as diesel prices move. Fuel is one of the major operating costs in trucking, so carriers often use a separate fuel surcharge to account for changes in fuel costs without constantly renegotiating the underlying transportation rate.
In trucking, carriers commonly tie fuel surcharges to diesel prices and calculate them on a per-mile or percentage basis. The specific method depends on the carrier, shipper, contract, and transportation arrangement.
Understanding the calculation can help shippers evaluate freight costs, compare rates, and see why the final transportation charge may change even when the base freight rate stays the same.
What Is a Fuel Surcharge in Trucking?
A fuel surcharge is an additional transportation charge that accounts for changes in fuel costs.
Instead of changing a shipment’s base freight rate every time diesel prices move, a carrier can apply a separate fuel surcharge. This approach adjusts the fuel-related portion of transportation costs while keeping the underlying freight rate separate.
Diesel prices can fluctuate based on crude oil prices, refining and distribution costs, taxes, regional market conditions, and broader supply and demand.
The federal government doesn’t mandate a single fuel surcharge rate or formula. The U.S. Energy Information Administration (EIA) publishes diesel price data that many transportation companies use as a reference, but it doesn’t calculate, regulate, or prescribe fuel surcharges. Carriers and shippers establish the methodology used for their shipments.
How Does a Fuel Surcharge Work?
A fuel surcharge typically starts with a benchmark diesel price.
Many trucking companies use the EIA’s Weekly Retail On-Highway Diesel Prices or an applicable regional diesel price as their benchmark. The EIA collects diesel prices from retail outlets across the country and publishes national and regional averages each week.
A carrier may compare the current diesel benchmark with an agreed base fuel price. When diesel rises above that baseline, the surcharge increases according to the formula or schedule in the transportation agreement. When diesel prices decline, the surcharge can decrease.
Transportation agreements don’t all use the same calculation. Some calculate a per-mile fuel surcharge, while others apply a percentage surcharge to the linehaul or transportation charge.
How to Calculate a Fuel Surcharge
There’s no universal fuel surcharge formula for every trucking company. A common fuel surcharge calculation uses three variables:
- The current diesel price
- An agreed base fuel price
- The truck’s assumed fuel efficiency, measured in miles per gallon (MPG)
A common per-mile formula is:
Fuel Surcharge per Mile = (Current Diesel Price − Base Fuel Price) ÷ Miles per Gallon
The carrier and shipper establish the base fuel price and MPG assumption as part of their fuel surcharge methodology. Different inputs can produce different surcharges even when two companies use the same diesel benchmark.
Fuel Surcharge Formula Example
Suppose a transportation agreement uses:
- Current diesel price: $5.00 per gallon
- Base fuel price: $3.00 per gallon
- Assumed fuel economy: 6 MPG
Subtract the base fuel price from the current diesel price:
$5.00 − $3.00 = $2.00
Divide the difference by the assumed fuel efficiency:
$2.00 ÷ 6 MPG = $0.333 per mile
The fuel surcharge is approximately $0.33 per mile.
For a 1,000-mile shipment:
1,000 miles × $0.333 = $333
The shipment would have an approximate $333 fuel surcharge in addition to the applicable base transportation charges.
This example illustrates one common method. Transportation providers may use different formulas, fuel efficiency assumptions, base prices, mileage calculations, and rate structures.
Calculating a Fuel Surcharge Per Mile
To calculate a fuel surcharge per mile:
- Identify the diesel price used as the current benchmark.
- Subtract the agreed base fuel price.
- Divide the difference by the agreed MPG.
- Multiply the surcharge per mile by the shipment’s applicable mileage.
For example, a $0.33-per-mile fuel surcharge on an 800-mile shipment equals:
800 × $0.33 = $264 fuel surcharge
The transportation agreement determines which mileage figure applies, so the calculation won’t always use the exact number of miles driven.
Calculating a Percentage-Based Fuel Surcharge
Some transportation agreements use a percentage instead of a fixed amount per mile.
Under this structure, the carrier typically applies the fuel surcharge percentage to the linehaul charge:
Fuel Surcharge = Linehaul Charge × Fuel Surcharge Percentage
If the linehaul charge is $2,000 and the applicable fuel surcharge is 15%:
$2,000 × 15% = $300
The transportation charges would include the $2,000 linehaul charge plus a $300 fuel surcharge, before any other applicable charges.
Carriers may use a fuel surcharge table or schedule that connects diesel price ranges with corresponding surcharge percentages. The exact methodology depends on the transportation agreement.
Shippers should review both the percentage and the method used to determine it when comparing transportation costs.
How Diesel Prices Affect Fuel Surcharges
Diesel prices play a central role in many fuel surcharge calculations. Transportation companies often use published diesel prices as a benchmark and adjust their surcharges as that benchmark changes.
Diesel Prices Used for Fuel Surcharges
Many transportation companies reference diesel price data from the U.S. Energy Information Administration.
The EIA’s Weekly Retail On-Highway Diesel Prices provide national and regional diesel averages that companies can use as benchmarks for fuel surcharge calculations.
The EIA provides the fuel price data, not the surcharge. It doesn’t calculate, assess, or regulate transportation fuel surcharges. Carriers and shippers establish their own methodologies.
Diesel prices have moved considerably during 2026. According to the EIA’s U.S. No. 2 Diesel Retail Prices, the national monthly average for on-highway diesel was $3.722 per gallon in February 2026, $4.921 in March, $5.501 in April, and $5.600 in May. The average declined to $5.024 in June and $4.955 in July.
Transportation agreements can use a separate fuel adjustment mechanism to account for these changes instead of permanently incorporating a fixed fuel cost into the base freight rate.
Why Diesel Prices Change
Several factors influence diesel prices:
- Crude oil prices
- Refining costs and capacity
- Distribution and marketing costs
- Federal, state, and local taxes
- Regional supply conditions
- Global petroleum supply and demand
Companies don’t all update their fuel surcharges on the same schedule. Some use weekly EIA data, while others follow the schedule established in their transportation agreement.
Fuel Surcharge vs. Base Freight Rate
A fuel surcharge and a base freight rate cover different components of transportation pricing.
The base freight rate covers the underlying transportation service. The fuel surcharge accounts for fuel costs according to the applicable pricing methodology.
Separating the two allows transportation pricing to respond to changes in diesel costs without requiring carriers and shippers to continuously renegotiate the underlying freight rate.
Shippers should consider both charges when comparing freight shipping rates and evaluating the total transportation cost.
FAQ
How is a fuel surcharge calculated?
Carriers can calculate fuel surcharges in several ways. A common trucking method subtracts an agreed base fuel price from the current diesel price and divides the difference by an assumed MPG. Other transportation agreements use percentage-based surcharges or predetermined fuel surcharge schedules.
How does a fuel surcharge work?
A fuel surcharge adjusts transportation costs as fuel prices change. Carriers generally charge it separately from the base freight rate, and the amount may rise or fall based on the diesel benchmark and surcharge methodology established in the transportation agreement.
What is a fuel surcharge in trucking?
A trucking fuel surcharge is an additional charge that accounts for changes in diesel fuel costs. It allows carriers to adjust the fuel-related portion of transportation pricing without necessarily changing the underlying freight rate.
How do you calculate a fuel surcharge per mile?
A common formula is (current diesel price − base fuel price) ÷ MPG. Multiply the resulting surcharge per mile by the applicable shipment mileage to calculate the total fuel surcharge.
Is there a standard fuel surcharge rate?
No. The federal government doesn’t mandate a single fuel surcharge rate for trucking. The EIA publishes diesel price data that many companies use as a benchmark, while carriers and shippers determine their own fuel surcharge formulas and agreements.