Calculate a Truckload Fuel Surcharge From the DOE Index

To calculate a truckload fuel surcharge, you take the current DOE diesel price, subtract the peg price in your contract, divide by the assumed miles per gallon, and multiply by the billed miles. That is the whole formula:

(DOE price per gallon - peg price per gallon) ÷ assumed MPG = fuel surcharge in dollars per mile

If you would rather not do the arithmetic by hand, our fuel surcharge calculator runs this against the real DOE price for any week in the last five years.

Every fuel surcharge argument is a fight about which four numbers go into that equation. Which DOE price (national or regional, and from which week). Which peg. Which MPG. Which mileage figure. Get those four and you can recompute any truckload surcharge in about thirty seconds, and tell the carrier exactly where their number came apart.

Most shippers never do this. They see “FSC: $289.33” on the invoice, note that diesel is expensive, and approve it. On a typical truckload lane the surcharge is the second largest number on the bill, and the one almost nobody checks.

What the DOE index actually is

The number everyone calls “the DOE index” is the Weekly Retail On-Highway Diesel Prices series published by the Energy Information Administration, an agency inside the Department of Energy. It is not a market quote or a futures price. It is a survey.

Per EIA’s published methodology, the price comes from Form EIA-888, collected from 590 retail diesel outlets across the contiguous United States. What gets recorded is the cash, self-serve pump price including taxes, as of 8:00 a.m. local time on Monday. The results publish Tuesday morning, and shift to Wednesday when Monday is a federal holiday.

Three things follow from that, and all three matter on an invoice:

• It includes taxes. It is a retail pump price, not a rack price, so a carrier buying negotiated bulk fuel is reimbursed against a retail benchmark. That is a design choice in the mechanism, not an error, but it is worth knowing when someone tells you the surcharge merely “covers cost.”
• It is one price per week. A load picking up Thursday is priced off a survey taken the previous Monday. Your contract has to say which week’s number applies to which shipment, and that lag is where a large share of fuel surcharge overbilling lives. Working out which DOE week governs a given pickup date is a separate exercise from the arithmetic below, and it is the one people skip.
• It is published by region, not just nationally. This is the part that quietly moves the most money.

Which region your contract names, and why it changes the number

EIA publishes the on-highway diesel price nationally and broken out by PADD (Petroleum Administration for Defense District), plus separate lines for California and for the West Coast excluding California:

These are not close to each other. For the week ending July 27, 2026, EIA reported a U.S. average of $5.313 per gallon, with the Gulf Coast at $5.087 and California at $6.670. That is a spread of more than $1.58 per gallon between two published numbers, both of which are legitimately “the DOE price.”

Run those through the same formula, holding a peg of $2.50 and an assumed 6.0 MPG (illustrative assumptions, see below), on a 620-mile lane:

Same load, same week, same formula, and a $163 spread depending only on which published series you read. If your contract says “the DOE index” with no further qualification, you have not agreed on a number. You have agreed on a family of numbers, and the carrier picks. Name the series explicitly: “the EIA Weekly Retail On-Highway Diesel Price, U.S. average,” or the specific PADD.

A regional index is defensible when a carrier runs a dedicated fleet inside that region. It is much harder to defend on a Dallas to Memphis lane billed off the California series.

The worked example, step by step

Everything below uses illustrative numbers. They are shaped like real contract terms but they are not quoted from any carrier’s tariff and the diesel price is not the current one. Use your own contract’s figures.

Assume:

• DOE price for the applicable week: $5.30 per gallon (illustrative)
• Peg price in the contract: $2.50 per gallon
• Assumed fuel economy: 6.0 MPG
• Billed miles: 620
• Linehaul: $1,240 (that is $2.00 per mile, illustrative)

Step 1. Find the amount above the peg.

$5.30 - $2.50 = $2.80 per gallon

This is the only part of the diesel price the surcharge covers. Everything below $2.50 a gallon is baked into the linehaul. That is what a peg is: the diesel price the line rate was set to absorb.

Step 2. Convert dollars per gallon into dollars per mile.

$2.80 ÷ 6.0 MPG = $0.466667 per mile

A truck at 6.0 MPG burns a gallon every 6 miles, so each dollar per gallon above the peg costs about 16.7 cents per mile.

Step 3. Multiply by the miles.

$0.466667 × 620 = $289.33

Step 4. Sanity-check it against the linehaul.

$289.33 ÷ $1,240 = 23.3 percent of linehaul. If your other carriers on similar lanes land near that and this one bills 41 percent, one of the four inputs is different, and it is worth finding out which.

Then check the rounding. Carriers publish the per-mile surcharge rounded to the cent or to a tenth of a cent. At $0.47 per mile the same load bills $291.40, at $0.466 it bills $288.92. Not worth one phone call, worth noticing at 400 loads a month.

How the surcharge moves when the index moves

Because the formula is linear, the surcharge moves in perfectly predictable steps. Hold the peg at $2.50 and MPG at 6.0, and every $0.10 change in the DOE price moves the surcharge by $0.10 ÷ 6.0 = 1.67 cents per mile, which on this 620-mile lane is $10.33.

Two checks fall out of this. First, truckload surcharges are continuous: no brackets, so a one-cent diesel move produces a fraction-of-a-cent per-mile move, every week. Second, if diesel falls below the peg the formula goes negative. Almost every contract floors the surcharge at zero rather than crediting the shipper, but the contract has to say so. If yours is silent, have that conversation before diesel drops, not after.

The peg and the MPG assumption are the two levers nobody negotiates

Shippers negotiate linehaul rates to the penny and then accept the fuel surcharge mechanism as though it came down from a regulator. It did not. The DOE index is fixed and public and nobody is going to change it. The peg and the MPG are pure contract terms, and both are as negotiable as the line rate.

Here is what they are worth. Same illustrative $5.30 DOE price, same 620-mile lane, per mile:

At the corners: 7.0 MPG against a $3.00 peg bills $203.71 on this load. 5.0 MPG against a $1.25 peg bills $502.20. Identical lane, identical week, identical published index, and a 2.5x difference produced entirely by two numbers in a contract nobody read closely.

On the peg. A low peg (the legacy figure near $1.25 that still turns up in old contract templates) means the linehaul was theoretically priced against diesel at that level. If your linehaul was actually negotiated in a year when diesel was $4.00, a $1.25 peg is charging you twice for the same fuel: once inside the line rate and again in the surcharge. Ask what diesel price the linehaul assumes. If the carrier cannot answer, the peg is not derived from anything.

On the MPG. A lower MPG assumption produces a larger surcharge, and “6 MPG” is a rule of thumb that has quietly persisted through two decades of fuel economy improvement. Unlike the peg, this is a factual claim about equipment, which makes it arguable with data. Moving 6.0 to 6.5 is worth 3.6 cents a mile at the numbers above.

The third lever is a cap. A ceiling on cents per mile, or on the surcharge as a percentage of linehaul, bounds your exposure in a spike. Carriers will often trade a cap for a slightly lower peg.

Why an LTL fuel surcharge table is a different animal

If you also move LTL, do not carry this arithmetic over. LTL fuel surcharges are structurally different in three ways.

They are a percentage, not a per-mile amount. The LTL surcharge is a percentage applied to the linehaul charge, so it scales with the rate rather than with distance. A short, expensive shipment carries a large fuel surcharge; a long, cheap one carries a small one.

They are stepped, not continuous. The carrier publishes a bracket table keyed to the same EIA number. Illustrative shape:

Inside a bracket, a nine-cent move in diesel changes nothing. At a boundary, a one-cent move changes the surcharge by half a point on every shipment. On an $850 linehaul that boundary is worth $4.25, and it produces the classic LTL fuel error: the invoice used the bracket from the wrong week, and the wrong week sat on the other side of a step.

The base the percentage applies to is itself contested. Is the percentage taken on gross linehaul or on linehaul after your discount? Order of operations changes the total. And does the surcharge touch accessorials? Fuel applied to a liftgate fee is a defensible tariff term if the tariff says so and an overcharge if it does not, and if the liftgate itself should never have been billed, the fuel on top of it goes with it when you dispute the liftgate charge on a dock delivery.

Both methods share one input. Both key off the same published EIA number, so both have the same failure mode: the wrong week, or the wrong region.

What to check on your next fuel surcharge

Pull one invoice and one contract and work through this in order.

1. Find the four inputs in the contract. Named index series (national or which PADD), peg, MPG, and the mileage basis. If any one of them is missing from the contract, that is the finding.
2. Find the applicable week. Your contract defines which EIA release governs which pickup dates. Look up that week’s number on the EIA weekly series rather than trusting the number printed on the invoice.
3. Recompute. (Index - peg) ÷ MPG × miles. Compare to the invoiced amount.
4. Check the miles. The mileage in the formula should be the same mileage the linehaul was rated on. Practical miles and shortest miles from the same engine can differ by several percent on the same lane, and that difference flows into both the linehaul and the fuel.
5. Check the surcharge as a percentage of linehaul across your carriers on similar lanes. Outliers point at a different peg or a different MPG, not at a bad week.
6. Dispute in writing, with the arithmetic in the body of the email. Fuel surcharge disputes settle faster than almost any other billing dispute, because there is no judgment involved. Either the inputs match the contract or they do not.

Do not sit on it. A shipper’s right to contest a bill is time-limited, and the clocks are shorter than most people assume. See every freight billing deadline with the regulation behind it for the windows that apply to contesting an invoice.

If you are the shipper

Your leverage is at contract time, not invoice time. Recomputing catches errors worth tens of dollars a load; renegotiating the peg and the MPG is worth hundreds. Do the recomputation anyway, because a quarter’s worth of recomputed invoices is the evidence you take into the next rate negotiation.

If you are the broker

You have two fuel surcharge mechanisms per load, one on the customer rate confirmation and one on the carrier agreement, frequently built on different pegs, different MPG assumptions, or different index weeks. That gap is margin, in whichever direction it points. Reconcile the carrier’s fuel line against the carrier rate con, then against what you billed the customer, and treat any structural difference as a pricing decision rather than an accident. The mechanics of that comparison, field by field, are in what to do when the rate confirmation and the carrier invoice disagree. The same discipline applies to accessorials: a charge you paid and did not pass through is the same leak as fuel computed on the wrong peg, and both are won with the underlying document, as in disputing a detention charge when the POD has no in or out times.

Sources

• EIA, On-Highway Diesel Fuel Price Survey: procedures and methodology (Form EIA-888, 590 retail outlets, cash self-serve pump price including taxes as of 8:00 a.m. local Monday, Tuesday publication and Wednesday when Monday is a federal holiday, PADD plus national and California breakouts)
• EIA, Gasoline and Diesel Fuel Update (week ending July 27, 2026 national and regional on-highway diesel prices)
• EIA, Weekly U.S. No 2 Diesel Retail Prices (weekly on-highway ultra-low-sulfur diesel retail price series)
• FreightWaves, Fuel surcharges in trucking (trade-press explainer on how surcharges are set, updated, and negotiated)