3 Ways High Fuel Costs Hit a Trucking Company, and the Surcharge Math

Diesel averaged $5.967 a gallon in the week of September 7, 2026, up $0.368 on the week and $2.201 on the year, according to EIA. For a truck running 100,000 miles a year at the national average of 6.9 miles per gallon, according to NACFE, that year-over-year jump alone is about $31,900 more fuel, before a surcharge recovers any of it. High fuel costs reach a trucking company three ways: through cost per mile, through capacity, and through a surcharge that lags the pump. Here is each one, with the math to recover it.

The carriers that come through a fuel spike are the ones that know their cost per mile per truck, per week, not per quarter. That is a data problem before it is a pricing problem: fuel card transactions have to land against the right truck and miles against the right trip. Trucking dispatch software that builds every load on one trip record does that as a byproduct of dispatching, which is why it turns up in every section below.

1. Fuel is the cost-per-mile line that moves every week

Every other line in cost per mile changes at renewal: insurance once a year, truck payments when the truck is bought, driver pay when the pay package changes. Fuel changes every time a driver pulls up to a pump. ATRI put the average cost of running a truck at $2.336 per mile in 2025, before this year's diesel increase.

The arithmetic from the two public numbers above: at 6.9 miles per gallon and $5.967 diesel, fuel alone is about $0.86 per mile. At the same fuel economy a year earlier, with diesel $2.201 cheaper, it was about $0.55. A truck running 7.5 miles per gallon pays about $0.80 today; one running 6.0 pays about $0.99. That spread between trucks in the same fleet is why cost per mile has to be a per-truck number. Our guide to calculating and reducing cost per mile walks through the full stack.

2. Capacity tightens as owner-operators park

When diesel jumps faster than rates, the first trucks to leave the market are the ones with the least cushion: owner-operators and small fleets on the spot market, where the surcharge is whatever the load pays that day. Some park and wait; some lease on to a larger carrier with a contract surcharge; some sell the truck. Each one is a truck that stops taking loads in the lanes with the worst fuel math: rural backhauls, lanes where pump prices run above the national average, and any load that ends far from the next one.

For the fleets that stay, that is the second impact: freight in those lanes gets harder to cover, and a dispatcher who does not price the empty miles to the next load into the quote is hauling them for free. The deadhead math is the same math as the surcharge math, and it belongs on the same trip record.

3. The surcharge lags the pump

A fuel surcharge is built to move with the EIA weekly average, and it does. The lag is in the mechanics. A typical program takes the published price from one day of the week and applies it to that week's loads, so a price that jumps $0.368 in one week, as it did in the week of September 7, is recovered a week late. On the spot market there is often no program at all: the rate is all-in, and the fuel is whatever is left after the linehaul.

The gap is largest for the fleets that need it most. A contract carrier with a written surcharge recovers most of an increase, late. A spot carrier recovers what the market gives. That is why, in a spike, pricing power moves toward the carriers with contracts and away from the ones without.

How to set a fuel surcharge that tracks the EIA index

The formula is short. Surcharge per mile equals this week's EIA average diesel price, minus the base price written into the contract, divided by the fuel economy written into the contract. Three inputs, all of them yours to negotiate except the EIA price.

A worked example with round inputs: base price $4.00 a gallon, contract fuel economy 6.0 miles per gallon, this week's EIA average $5.967. ($5.967 minus $4.00) divided by 6.0 is $0.328 per mile. On a 600-mile load that is about $197 of surcharge on top of the linehaul. If the truck actually runs 6.9 miles per gallon, the surcharge over-recovers a little and the fleet keeps the difference; if it runs 5.5, the fleet eats it. That is why the fuel economy in the contract matters as much as the base price.

Three things to put in writing: which EIA series the program uses (the national average or a regional one), which day's price applies to which loads, and what happens when the price falls below the base. Then check the arithmetic on every rate confirmation. A surcharge that is in the contract but not on the invoice is fuel money left on the table.

What a TMS does with fuel data

None of the math above is hard. What is hard is having the inputs in one place on the day the rate is quoted. A TMS built on one trip record does three things with fuel:

• Fuel card integrations land every transaction against the truck and driver that bought it, so cost per mile is per truck and per week, not a quarterly average.
• The fuel surcharge is a rate line on the load, so it appears on the rate confirmation, the invoice and the driver settlement without being keyed three times.
• Jurisdiction miles from the mileage integration and fuel purchases by state and province come off the same records, so the IFTA quarter is a report rather than a weekend. On TransPlus, IFTA reporting (Enterprise plan) produces the quarterly report; you or your filing service submit the return.

TransPlus Fleet Manager builds the load once, and the surcharge, the invoice and the settlement come off that record; fuel card and telematics integrations are among its 66 integrations. See trucking dispatch software, check plans from $350 per month for one user, or book a personalized demo, scheduled the same week you ask, with no commitment.

Related reading: how trucking companies can combat rising diesel fuel prices, 10 ways to improve semi truck fuel economy, and how to calculate and reduce cost per mile.