How fuel surcharges work

A fuel surcharge is the contract line that passes fuel-price risk from the carrier to the shipper. It runs off one simple mechanic: a schedule sets a base fuel price called the peg, then adds a fixed amount per mile for every increment the DOE diesel number sits above that peg, at a stated miles-per-gallon figure. When the DOE number rises, the surcharge rises on the formula. When it sits at or below the peg, the surcharge is zero.

The formula

Almost every schedule is the same arithmetic underneath. Surcharge per mile equals the DOE diesel price minus the peg, divided by the assumed miles per gallon. Say the peg is a dollar and change and the DOE number is well above it. The gap between them is the extra fuel cost per gallon over the base, and dividing by the assumed mpg turns that into an extra fuel cost per mile, which is the number handed to the shipper on each mile of the load.

Every schedule is a private contract

EIA publishes the index and nothing more. It states plainly that it does not calculate, assess or regulate fuel surcharges, that shippers, transportation companies and truckers use its weekly retail price in their own pricing formulas, and that each company can set its own method. So the index is public and identical for everyone, the schedule is a negotiated term, and two loads reading the same DOE number can carry very different surcharges depending on whose schedule governs them.

The chart above is the DOE number the schedules read. It updates once a week, so a surcharge set against it usually holds for the week and resets on the next release.

The four numbers that define a schedule

Read any surcharge schedule and four things decide what it pays. The peg, the base price where the surcharge starts. The increment, how big a DOE move triggers each step. The mpg basis, the truck economy the schedule assumes. And which DOE figure it reads, the US average or one of the PADD regional versions. A common rule of thumb from OOIDA is roughly one cent per mile of surcharge for every six-cent move in diesel above the base, which works out to about a 6 mpg basis. An owner-operator has to know which of these govern a load, because they set what actually lands on the settlement.

Worked example: one week, one haul

Take an illustrative schedule, and read illustrative as doing real work here, because yours will differ. Set the peg at $1.25 a gallon, the basis at 6.5 mpg, the surcharge stepping continuously above the peg. At the DOE number for the week of Jul 6, 2026, $4.578 a gallon (the live figure is on the chart above), the gap over the peg is $3.328. Divide that by 6.5 mpg and the fuel surcharge is about 51.2 cents per mile. On a 500-mile haul that is about $256 of surcharge for the week.

Now change one input. Move the peg to $1.20 or drop the basis to 6.0 mpg and the same DOE number produces a different surcharge on the same haul, because a lower assumed mpg means the schedule treats each mile as burning more fuel. That is the whole reason to read the schedule that governs your load rather than a generic calculator: the peg and the basis are as much a part of the number as the DOE price is.

Continuous formulas and bracket tables

Schedules come in two shapes and both peg to the DOE number. A continuous formula is the arithmetic above, recalculated on every release. A bracket table does the same thing in steps: it lists price bands, say the DOE number between $4.50 and $4.56, and assigns a fixed surcharge per mile to each band. The table is easier to read off a rate confirmation, the formula is smoother, and neither is more correct. Because the DOE number updates once a week, a surcharge set either way normally holds Tuesday to Tuesday and resets on the next release. Some schedules also quote the surcharge as a percentage of the linehaul rather than cents per mile, and some cap or floor it, which is one more reason to read the specific terms on the load.

Which DOE number the schedule reads

One detail decides more than it looks. A schedule can peg to the US national average or to a PADD regional version of the DOE number, and on the West Coast the difference is large. A load priced off the national average pays the same surcharge whether it runs through Georgia or California, even though the pump price in those two places is more than a dollar apart. A regional peg tracks closer to what the truck actually pays. Knowing which figure a schedule reads is part of knowing what the surcharge is worth on your lanes.

Monday Diesel reports the DOE index the schedules read and shows the arithmetic that turns it into cents per mile. It does not tell a reader what peg, basis or increment to accept, or what surcharge to set or pay. Those are contract terms between you and your counterparty.

Monday Diesel is a free weekly read of the DOE diesel number and what it does per mile. Built entirely from EIA's public data, in your inbox before dispatch, one email a week.