Fuel Surcharge in Trucking: How It Works at $6.28 Diesel

Figures current as of 18 September 2026. Every number is linked to its source where it appears.

Take two invoices for the same dry van load, Chicago to Dallas, one from June and one from this week. The linehaul rate is identical. The total is not, and the whole difference sits on one line: the fuel surcharge. If you have never had to read that line closely, this is the month you will, because diesel has just set a record and the fuel surcharge in trucking is moving faster than anything else on a freight bill.

This guide explains what the surcharge is, exactly how carriers and brokers turn a diesel price into a per-mile or percentage charge, what the numbers are right now, and, most usefully, which parts of the calculation a shipper can question.

Quick Answer: What Is a Fuel Surcharge in Trucking?

A fuel surcharge in trucking is a separate, adjustable charge added to the base freight rate that rises and falls with the weekly price of diesel. It exists so the base rate can stay fixed for months or a year while the fuel portion tracks the market. The shipper pays it as a line item, and its formula is set by contract, not by regulation.

Two things follow from that definition. First, the surcharge is not a fee for something extra; it is part of the price of moving your freight, split out so both sides can see how much of the cost is fuel. Second, because the formula is a commercial term, two providers can quote the same base rate and still bill you different fuel amounts. That gap is where a shipper's attention should go.

Why Fuel Surcharges Exist (and Why Nobody Regulates Them)

Diesel is the second largest cost of running a truck after the driver, and it is the only large cost that can move 30 cents a gallon in a single week. Base freight rates do not work like that. A contract rate is typically fixed for a year, and even a broker's lane pricing is revisited monthly at most. If fuel were buried inside the base rate, a carrier would either lose money every time diesel rose or pad every quote to protect itself against the possibility.

The surcharge solves the mismatch. The base rate covers the truck, the driver, the equipment, and the margin. The fuel surcharge covers the difference between the fuel price that was assumed when the base rate was set and the fuel price on the road this week. When diesel falls, the surcharge falls with it, which is the part shippers sometimes forget to check.

One point worth stating plainly: there is no federal rule that requires a fuel surcharge in trucking or dictates how it is calculated. Congress considered bills in 2008 that would have forced surcharges to be passed through to whoever bought the fuel (the TRUCC Act among them), and the only version that became law applies to Department of Defense freight. For commercial shipments, surcharges remain, in FreightWaves' words, commercial terms rather than regulated formulas. Everything about yours, from the index it follows to the day of the week it updates, lives in your rate agreement or the carrier's published tariff.

How a Fuel Surcharge Is Calculated

There are two common methods. Truckload freight almost always uses a per-mile surcharge. LTL and parcel carriers use a percentage of the linehaul charge. Both start from the same public number.

The three inputs

The index. Nearly every surcharge in the United States is pegged to the national average on-highway diesel price published by the U.S. Energy Information Administration every Monday afternoon. You will see it called the DOE price or the EIA price; they are the same figure. Some contracts use one of EIA's regional prices instead of the national average, which matters when the regions diverge.

The base price. This is the diesel price at which the surcharge is zero, sometimes called the peg or the threshold. Most agreements set it somewhere between $1.20 and $1.50 a gallon. It is a contract term, not a market number, and it has not changed in most agreements for well over a decade even though diesel has.

The fuel economy assumption. The formula needs to convert dollars per gallon into dollars per mile, so it assumes a truck's miles per gallon. Agreements typically use 6.0 to 7.0 MPG. A modern tractor on a highway lane often does better than that, which is why this input deserves scrutiny.

The formula, worked at this week's price

The per-mile method takes this week's diesel price, removes the base price, and divides what is left by the assumed miles per gallon:

Fuel surcharge per mile = (current diesel price minus base price) divided by MPG

Here it is with EIA's reading for the week of 14 September 2026, which was $6.285 a gallon, and the most common contract assumptions:

The base rate on that lane could be unchanged from a year ago and the invoice would still be roughly $392 higher, all of it fuel. That is the mechanism behind a lot of the sticker shock shippers are reporting this month, and it is why we treat the surcharge as its own subject rather than folding it into our guide on why truck freight rates are rising in 2026.

How LTL does it differently

LTL carriers do not price by the mile, so they cannot surcharge by the mile. Instead, each carrier publishes a table that maps the weekly EIA price to a percentage, and that percentage is applied to the net linehaul charge on every shipment.

These tables are public. Old Dominion, for example, posts its history on its fuel surcharge page. Its rate effective 16 September 2026 is 50.32 percent of linehaul. Its posted rate for the week of 23 to 29 September is 53.32 percent. One year earlier the equivalent figure averaged 27.82 percent.

Put that on a single pallet with a $600 linehaul charge, the kind of shipment we price every day in our guide to how much it costs to ship a pallet:

The linehaul did not move. The fuel line nearly doubled. If your LTL invoices have jumped and your freight class and weight have not changed, this table is almost certainly the reason.

What the Surcharge Looks Like Right Now: The 2026 Numbers

The reason so many people are searching for how surcharges work this month is that both inputs have moved sharply and at the same time.

EIA's weekly diesel series tells the story of the year. The figures below are from the agency's published history, and the surcharge column is DAT's national average dry van fuel surcharge for the month, in cents per mile, where DAT has published it.

The March jump from 41 to 61 cents per mile is documented in DAT's April release, where its chief of analytics noted that van surcharges had averaged around 40 cents through most of 2025. The August figure of 70 cents comes from DAT's 15 September release. Diesel has risen another dollar a gallon since the August average, so the September surcharge figure, when it lands, will be higher again.

The 14 September reading is the highest in EIA's weekly series, up 31.8 cents in one week and $2.546 above the same week last year. The full-year 2025 average was $3.66. In other words, a shipper budgeting on last year's fuel is budgeting on a diesel price that is now about 70 percent too low. The causes are geopolitical and sit outside the freight market; we cover them in the rates article linked above rather than repeating them here.

The Two Numbers a Shipper Can Negotiate

Here is the part most explainers skip because they are written for the people receiving the surcharge, not the people paying it. Of the three inputs, the diesel index is public and beyond anyone's control. The other two are contract terms, and each of them moves the result by a meaningful amount.

The base price

Every cent the base price is set lower adds to the surcharge at every diesel price, forever. At this week's $6.285, moving the peg from $1.25 to $1.50 lowers the surcharge from about 84 cents a mile to about 80 cents. On the 925 mile Chicago to Dallas lane, that is roughly $39 per load. Pegs at that level date from the years when diesel really did cost that much: EIA's history shows the national average between $1.11 and $1.51 every year from 1995 to 2003. Many agreements have carried the same number ever since, and there is nothing wrong with asking why.

The MPG assumption

This one moves the result more. At $6.285 diesel and a $1.25 peg, an agreement written at 5.5 MPG produces about 92 cents a mile. The same agreement at 6.5 MPG produces about 77 cents, and at 7.0 MPG about 72 cents. Between a padded contract (5.5 MPG, $1.25 peg) and a lean one (7.0 MPG, $1.50 peg), the difference this week is about 23 cents a mile, which is over $200 on one Chicago to Dallas load. Agreements are commonly written anywhere from 6.0 to 7.5 MPG, and a current tractor on a highway lane usually runs toward the top of that range rather than the bottom, so an assumption below 6.0 is a number to challenge.

Four questions to ask before you sign or renew

Which index and which region?

Confirm whether the surcharge follows EIA's national average or a regional price. On 14 September the Midwest (PADD 2) price was $6.250 against a national $6.285. Small, but on a Midwest-only lane it is the right number.

Which week's price applies?

Contracts differ on whether the surcharge is set by the pickup date, the tender date, or the week the invoice is cut. In a rising market, a tender-date rule is cheaper for you; in a falling market, the opposite. Most carriers update on Tuesday or Wednesday from Monday's EIA release, which is why the same load can carry a different surcharge depending on which day it moves.

Is the surcharge applied to linehaul only?

It should be. We occasionally see agreements where the percentage is applied to the full invoice including accessorial charges such as liftgate or detention. Fuel has nothing to do with a liftgate. Ask for the surcharge to sit on net linehaul alone.

Does it come down as fast as it goes up?

Any surcharge worth the name floats in both directions. If your agreement caps the downside adjustment or lags it by a month while the upside applies weekly, that is not a surcharge, it is a rate increase with a fuel label on it.

From the broker's side of the desk, the shippers who get the best fuel terms are not the ones who argue about this week's number, which nobody controls. They are the ones who asked about the peg and the MPG once, got them written down, and then stopped worrying about it.

Spot Quotes vs Contract Rates: The Comparison Mistake

Here is a mistake we see at least weekly. A shipper holds a contract rate of, say, $2.40 a mile plus fuel, gets a spot quote from a broker at $3.10 all-in, and concludes the spot market is 70 cents more expensive.

It is not, or at least not by that much. Spot rates in the truckload market are quoted all-in, with fuel already inside the number. DAT describes its broker-to-carrier spot rates as linehaul plus an equipment-specific fuel surcharge calculated from the latest weekly EIA price, and its weekly market reports break out how much of each move was fuel. Contract rates, by contrast, almost always show fuel as a separate line.

To compare properly, add this week's surcharge to the contract linehaul before looking at the spot number. At 84 cents a mile, that $2.40 contract is really $3.24 on the road this week, which is higher than the $3.10 spot quote, not lower. We walk through the structural differences in our comparison of spot rate vs contract rate.

There is a second consequence in a rising fuel market. An all-in spot quote locks the fuel for that load at the moment you accept it. A contract surcharge floats week to week, so a load tendered under contract today and picked up next week may carry next week's higher fuel. Neither is better in every case, but you should know which one you are holding.

How to Keep the Fuel Surcharge Down Without Cutting Corners

You cannot negotiate the price of diesel. You can reduce how much of it your freight consumes and how much of your invoice it is applied to.

Shorten the miles, not the service. A per-mile surcharge is exactly that. Consolidating two partial loads into one full truckload, or routing through a closer distribution point, cuts the surcharge in direct proportion to the miles saved.

Get the LTL linehaul right the first time. Because the LTL surcharge is a percentage of linehaul, every reweigh or reclass that raises the linehaul also raises the fuel charge on top of it. Accurate dimensions and the correct freight class on the bill of lading protect both lines at once. Our LTL service team checks this before the pickup rather than after the invoice.

Reduce out-of-route and idle miles. Drop-trailer arrangements, realistic appointment windows, and shipping-ready freight cut the deadhead and waiting that carriers price into both the base rate and, in some agreements, the surcharge.

Ask for the regional index where it is lower. For lanes that stay inside one region, a regional EIA price can be a fair and slightly cheaper peg, as the Midwest figure above shows.

Review the peg and MPG once a year. Put it on the same calendar as the rate renewal. Ten minutes on those two numbers is worth more than an hour arguing about any single invoice.

Common Questions About Fuel Surcharges in Trucking

Is a fuel surcharge mandatory?

No. No federal or state law requires one or sets its formula. It is a term of the agreement between the shipper and the carrier or broker. In practice almost every truckload contract and every LTL tariff includes one, because neither side wants fuel risk buried in the base rate.

How often does the fuel surcharge change?

Weekly for most carriers and brokers, following EIA's Monday release. LTL carriers typically apply the new percentage from Wednesday. Some contract agreements adjust monthly using an average of the weekly readings, which smooths the swings but lags them.

Does the surcharge apply to LTL and pallet shipments?

Yes, as a percentage of the linehaul charge rather than a per-mile amount. As of 16 September 2026 that percentage is above 50 percent at major LTL carriers, against under 30 percent a year ago.

Can a fuel surcharge go to zero?

In principle, if diesel fell to the base price in the contract. With pegs at $1.25 to $1.50 and diesel above $6, that is not a realistic scenario. What can and should happen is that the surcharge falls week by week when diesel falls.

Is the fuel surcharge negotiable?

The diesel price is not. The base price and the MPG assumption are, and the day-of-week and linehaul-only rules are too. Those four items are where a shipper's leverage is.

The Bottom Line

A fuel surcharge in trucking is the part of your freight rate that tracks diesel, split out so the base rate can stay stable. It is calculated from a public weekly diesel price, a contractual base price, and a contractual fuel economy assumption, or in LTL from a published percentage table. With diesel at a record $6.285 and LTL surcharges above 50 percent, it is now the fastest-moving line on any freight invoice.

Two things to check on your next bill: the peg and MPG in your agreement, and whether the percentage is sitting on linehaul only. If you want a quote where the fuel line is shown separately and the inputs are written down, request a quote online or phone The American Truck Inc. at (630) 884-1125. We are a licensed freight broker (MC 1631835, USDOT 4221571) and carry a BMC-84 surety bond.