A fuel surcharge is calculated by plugging the current national diesel price into a formula agreed upon between a shipper and carrier. There is no single government-mandated formula. Every contract can define its own method, but the freight industry relies on two widely used approaches: a cents-per-mile calculation (common in truckload shipping) and a percentage-of-linehaul calculation (common in less-than-truckload, or LTL, shipping). Both start with the same weekly diesel price published by the U.S. Energy Information Administration.
The Diesel Price Benchmark
Nearly every fuel surcharge in the U.S. trucking industry is tied to the EIA’s weekly “U.S. On-Highway Diesel Fuel Prices” report. The EIA publishes this number every Monday in dollars per gallon, and the price includes all taxes. The report also breaks out regional averages for areas like the East Coast, Midwest, Gulf Coast, Rocky Mountain, West Coast, and California, but most contracts reference the national average unless the shipper and carrier agree on a regional figure.
You can find the current and historical diesel prices on the EIA’s website under the “Gasoline and Diesel Fuel Update” page. Bookmark it if you calculate surcharges regularly, because the number resets each week and your surcharge resets with it.
Truckload: Cents-Per-Mile Formula
For full truckload (FTL) shipments, the surcharge is usually expressed as a dollar amount per mile driven. The formula has three components:
- Current diesel price: The EIA national average for the relevant week.
- Base diesel price: A threshold written into your contract, sometimes called the “trigger” or “floor.” This is the price per gallon below which no surcharge applies. Common base prices range from $1.20 to $1.50 per gallon, though contracts negotiated more recently may use a higher base.
- Miles per gallon (MPG): An assumed fuel efficiency for the truck, also set in the contract. Most agreements use a figure between 5.5 and 7.0 MPG.
The formula looks like this:
Fuel Surcharge Per Mile = (Current Diesel Price − Base Diesel Price) ÷ MPG
Say the EIA reports diesel at $3.80 per gallon this week. Your contract has a base price of $1.25 and assumes 6.0 MPG. The math is:
($3.80 − $1.25) ÷ 6.0 = $0.425 per mile
If the load covers 500 miles, the total fuel surcharge is $0.425 × 500 = $212.50, added on top of the base freight rate.
Two variables in this formula have an outsized effect on what you pay or collect. A lower base price increases the surcharge, because the gap between current diesel and the floor is wider. A lower assumed MPG also increases it, because the truck is burning more fuel per mile. When negotiating a contract, these two numbers matter as much as the linehaul rate itself.
LTL: Percentage-of-Linehaul Method
Less-than-truckload carriers handle shipments from many customers on a single truck, so a per-mile surcharge for each shipper doesn’t work cleanly. Instead, LTL carriers apply the fuel surcharge as a percentage of the linehaul charges (the base cost of moving your freight, before accessorial fees).
The carrier publishes a fuel surcharge matrix, which is essentially a lookup table. One column lists diesel price ranges in small increments, and the next column shows the corresponding surcharge percentage. Each week, the carrier checks the EIA diesel price published on Monday, finds the matching row in the table, and applies that percentage to every LTL shipment for the following seven days.
For example, a Department of Energy rate schedule used in government freight shows how this works in practice: if the Monday diesel price comes in at $3.561 per gallon, the matrix maps that to a 14.0% fuel surcharge. A shipment with $800 in linehaul charges during that week would carry a fuel surcharge of $800 × 0.14 = $112.
Private LTL carriers each publish their own matrices, and the percentages can vary significantly from one carrier to another at the same diesel price. When comparing LTL rate quotes, always pull up the carrier’s current fuel surcharge schedule and factor it into the total cost, not just the base rate.
How Often the Surcharge Changes
Most fuel surcharge programs reset weekly, pegged to the Monday EIA diesel report. In the LTL world, the new percentage typically takes effect the Wednesday after the Monday report and runs through the following Tuesday. Truckload surcharges often update on a similar weekly cycle, though some contracts specify biweekly or monthly resets.
The timing matters when you’re booking loads. If diesel jumps 15 cents between one Monday report and the next, a shipment picked up on Tuesday could carry a different surcharge than one picked up on Wednesday. Check your contract language to know exactly which reporting date applies to your shipment.
Running the Numbers on Your Own Contract
To calculate your fuel surcharge right now, gather three things:
- Your contract terms: Find the base diesel price, the assumed MPG (for truckload), or the surcharge matrix (for LTL). These are in your rate confirmation or tariff agreement.
- The current EIA diesel price: Go to the EIA’s Gasoline and Diesel Fuel Update page and note the most recent Monday figure for U.S. On-Highway Diesel.
- Your shipment details: For truckload, you need the mileage. For LTL, you need the linehaul charges.
Plug the numbers into the appropriate formula. For truckload, subtract the base price from the current price, divide by the MPG, and multiply by the miles. For LTL, look up the percentage and multiply it by your linehaul cost.
If you’re setting up a fuel surcharge program rather than calculating one that already exists, you’ll need to negotiate each variable. The base diesel price is the biggest lever. Setting it at $1.25 per gallon versus $1.50 creates a $0.04 to $0.05 per mile difference at today’s diesel prices, which adds up quickly over thousands of miles. The MPG assumption should reflect realistic truck performance for the type of freight being hauled. Heavier loads and mountainous routes burn more fuel, so a lower MPG figure is more accurate in those cases.
Many carriers and freight brokers provide online fuel surcharge calculators that pull the EIA price automatically and apply their contractual formula. These are convenient for quick checks, but always verify the underlying numbers match your contract terms, especially the base price and MPG, since defaults in a calculator may not reflect your specific agreement.