Surcharges · Hub

Fuel Surcharge: How It's Calculated and How to Audit It

Published September 13, 2026 · Rob Eller

A fuel surcharge is a separate line on a freight bill that moves the price of a shipment up or down with the price of diesel. Nearly every US carrier keys it to one public number: the US Energy Information Administration (EIA) weekly retail diesel price. That reading runs through a table or a formula and lands on your invoice as a percentage of linehaul for less-than-truckload (LTL) and parcel, cents per mile (truckload), or dollars per car (rail). The arithmetic is simple. The audit is about which inputs the carrier actually used.

Fuel surcharge (FSC) · A charge added to the linehaul rate that adjusts for diesel fuel cost movement, calculated from a public diesel index through a carrier table or a contract formula.

EIA diesel index · The Weekly U.S. No 2 Diesel Retail Price published by the Energy Information Administration every Monday afternoon, as a national average and five regional (PADD) subsets. Carriers, contracts, and audits all read from it.

Peg (or strike) price · The diesel price the carrier's base rate already assumes. Fuel surcharge only compensates for diesel above the peg. Truckload contracts commonly peg at $1.20 to $1.25 per gallon; rail programs at $1.25 to $2.50.

Surcharge table · The carrier's published scale that converts an index reading into a percentage or a per-mile figure. Tables are versioned, updated on the carrier's schedule, and the version in force on the pickup date is the one that governs.

Industry context

Across the freight audit industry, Trax Technologies cites 5–7% average annual savings on enterprise transportation spend, AFS Logistics claims up to 8% recovery on freight audit programs, and ConData reports identifying $645M in carrier overcharges across its enterprise client base. Fuel surcharge is the most-cited single line in those recoveries across every mode, because it is recalculated weekly on every shipment and each of its three inputs can be wrong without the invoice looking wrong.

What a fuel surcharge is, and why every mode has one

Carriers added fuel surcharges when diesel started moving faster than contract cycles. A rate negotiated in January with diesel at $2.80 is a loss for the carrier by June if diesel is at $4.10, and a windfall for the carrier if it drops to $2.20. The surcharge takes fuel out of the base rate and passes it through on an index instead, so neither side carries the bet. That is the theory, and it is a reasonable one.

In practice the surcharge stopped being a pure pass-through years ago. Carriers publish their own tables, re-base those tables when it suits them, and decide unilaterally what the surcharge applies to. On a typical LTL program the fuel line runs 25 to 35 percent of net linehaul, which makes it the second-largest number on the bill. On parcel it is commonly 15 to 30 percent of the base charge depending on service. A half-point error on a line that size, repeated across every shipment in a quarter, is real money.

The index everyone reads is the same. The EIA publishes the Weekly U.S. No 2 Diesel Retail Price every Monday afternoon (Tuesday when Monday is a federal holiday), as a national average and as five regional subsets corresponding to the Petroleum Administration for Defense Districts: East Coast (PADD 1), Midwest (PADD 2), Gulf Coast (PADD 3), Rocky Mountain (PADD 4), and West Coast (PADD 5). Which one your contract names, and which week's reading applies to a given pickup, is the first thing the audit checks.

How the surcharge is calculated, mode by mode

Four modes, three mechanics. The carrier-specific pages on this site (FedEx, UPS, rail) work each one to the invoice line. This is the map.

LTL: percentage of net linehaul from a table

LTL carriers publish a table that maps a band of the EIA reading to a surcharge percentage. A common shape steps 0.5 percentage points for every 5-cent move in the index, though tables vary: some step every 4 cents, some every 6, and the starting point of the scale differs by carrier. The percentage is applied to the net linehaul, meaning the tariff rate after your discount. On a shipment with a $2,400 gross tariff rate and a 68 percent discount, the net linehaul is $768. At a 31.0 percent surcharge the fuel line is $238.08. If the carrier applies the same 31.0 percent to the $2,400 gross, the line is $744.00. Same reading, same table, wrong base, three times the money.

Truckload: cents per mile from a formula

Full-truckload carriers usually skip the table and use a formula: (EIA reading − peg price) ÷ miles per gallon. With the industry-standard assumptions of a $1.25 peg and 6 miles per gallon, every 6-cent move in diesel is worth 1 cent per mile. At a $3.85 reading, the surcharge is ($3.85 − $1.25) ÷ 6 = $0.433 per mile. On an 850-mile lane that is $368.33 on top of linehaul. The three numbers that matter are the peg, the miles-per-gallon divisor, and the mileage source (practical vs. shortest route, and whose mileage software). All three should be in the contract. Usually one is missing.

Parcel: percentage of base charge, two indexes

UPS and FedEx apply a percentage to the base transportation charge. Ground services key off the EIA diesel index; air and express services key off a jet fuel index, which is why air surcharges run several points higher. The published percentage is not a clean read of the index: both carriers set their own table and have adjusted the surcharge percentage independently of fuel prices more than once. Both apply the reading with a lag of roughly two weeks between publication and the billing week it governs. The UPS and FedEx pages walk the tables.

Rail: per-mile scale above a strike price

Class I railroads convert the difference between the EIA reading and a strike price into cents per car-mile through a mileage band scale, and each railroad names a different regional subset of the index. The rail fuel surcharge page works the math per carrier.

Mode	Index	Mechanic	Applied to	Reading cadence
LTL	EIA diesel, national average (usually)	Table: index band → percentage	Net linehaul after discount	Weekly, keyed to pickup date
Truckload	EIA diesel, national or regional	Formula: (index − peg) ÷ miles per gallon	Loaded miles	Weekly, keyed to pickup date
Parcel	EIA diesel (ground); jet fuel (air)	Carrier table: index band → percentage	Base transportation charge, often accessorials too	Weekly, roughly two-week lag
Rail	EIA diesel, carrier-named PADD region	Scale: (index − strike) → cents per car-mile	Linehaul only	Weekly or monthly by program

Worked example: $14.5M LTL program, roughly $100K a year recovered on fuel alone

A regional building-products distributor tenders about 1,100 LTL shipments a month to three carriers under one master agreement. Average invoice is $1,100, so annual LTL spend runs about $14.5M and the fuel line runs about $3.4M of it. The contract says two things clearly: the surcharge percentage comes from the carrier's published table read against the EIA national average published the Monday preceding the pickup date, and it applies to net linehaul only.

Take one shipment. Tendered Friday, September 4. The Monday preceding pickup is August 31, when the EIA national average printed at $3.724. On the carrier's table that lands in the 31.0 percent band. Net linehaul is $768, so the fuel line should be $238.08. The invoice, dated September 10, shows fuel at $271.58.

Two things happened:

The carrier anchored to the invoice date, not the pickup date. The reading published September 8 was $3.781, which sits one band up at 31.5 percent. In a quarter when diesel is climbing, invoice-date anchoring overbills every shipment that is invoiced across a Monday boundary. On this program that was 41 percent of shipments. The per-shipment gap is small: 0.5 points on $768 is $3.84.
The carrier applied the surcharge to the $95 liftgate. 31.5 percent of $95 is $29.93. The contract limits fuel to linehaul. That error hit 23 percent of shipments, the ones with any accessorial at all, at an average accessorial value of $112.

Per month: 451 shipments at $3.84 is $1,732. 253 shipments with fuel on an average $112 of accessorials at 31 percent is $8,784. Together, about $10,500 a month, or $126K a year, on a $3.4M fuel line. With the EIA readings and the contract clause attached to each dispute, the carrier settled about 80 percent, which is roughly $100K recovered. None of it showed up as an anomaly in accounts payable, because every individual line was under $35.

“The fuel surcharge is the one line on a freight bill where the carrier and the shipper are reading the same public number. Every dispute I have ever won on it was about what the carrier did to that number after reading it.” — Rob Eller

Where the math goes wrong: six failure modes

After reviewing fuel lines on several hundred carrier contracts, these six account for nearly all of the recoverable dollars. The first two are the largest by far.

Wrong week. The contract keys the reading to pickup date; the carrier's system keys it to invoice date or to the day the bill was rated. In a rising market that overbills; in a falling market it underbills and the carrier will not tell you. Both are contract breaches. This is the most frequent fuel error in every mode.
Wrong base. The percentage is applied to the gross tariff rate instead of the discounted net, or to the full invoice instead of the linehaul. On a 60 to 80 percent discount program, gross-versus-net is a 2.5x to 5x multiplier on the fuel line.
Fuel on accessorials and minimums. Liftgate, residential, inside delivery, notification, and detention are not miles driven. Contracts almost never authorize fuel on them; billing systems apply it to the whole bill by default. Minimum-charge shipments are the cousin: whether fuel applies on top of the absolute minimum charge, or is already inside it, has to be stated.
Wrong table version. Carriers re-issue surcharge tables. The exhibit attached to your contract in 2024 and the table on the carrier's website today may differ by a full point at the same index reading. If the contract does not lock the version, the carrier's current table wins by default.
No cap, no floor. A contract with a table and no ceiling passes every carrier table revision straight through. A cap (say, 35 percent) is common in negotiated LTL agreements and is one of the more valuable lines to have.
Regional versus national index. The contract names the national average; the carrier reads PADD 5. Across a year the subsets diverge by 3 to 15 cents a gallon, which is one to three table bands.

What your contract should say

Three clauses close all six failure modes. The language below is the pattern we have seen hold up in disputes; adjust the numbers to your program.

Index anchor clause

“The fuel surcharge shall be calculated from the US Energy Information Administration Weekly U.S. No 2 Diesel Retail Price, national average, as published for the Monday immediately preceding the shipment pickup date. Where the EIA publication is delayed, the most recent published reading as of the pickup date shall apply.” Series, region, and the pickup-date anchor. Three of the six failure modes disappear.

Base clause

“The fuel surcharge shall be applied to the net linehaul charge after all discounts, and to no other charge. No fuel surcharge shall be applied to accessorial charges, minimum charges, or any charge other than linehaul.” Net, linehaul only, accessorials excluded, minimum charge treatment stated.

Table lock clause

“The fuel surcharge table applicable to this Agreement is attached as Exhibit C and shall govern for the term. Carrier may not substitute a revised table without sixty (60) days’ written notice and Shipper’s written acceptance. In no event shall the fuel surcharge exceed 35 percent of net linehaul.” The table lives in the contract, not on a website the carrier controls, and there is a ceiling.

What to ask your carrier

“What EIA reading, in dollars per gallon and by publication date, did you use for this PRO number (the carrier's shipment ID)?”
“Which table version and effective date was this rated against, and does it match Exhibit C?”
“Was the percentage applied to net linehaul, gross, or the full invoice?”
“Show me the fuel calculation on a shipment that carried a liftgate charge.”
“Do you key the reading to pickup date, ship date, or invoice date?”

What we can't tell from the bill alone

A fuel line on an invoice shows a dollar amount and, if you are lucky, a percentage. It does not show the reading the carrier used, the publication date of that reading, the table version, or the base the percentage was multiplied against. Every one of those has to be reconstructed, and the reconstruction needs four things: the EIA history for the audit window, the carrier's table by version and effective date, the contract clause, and the pickup date on each PRO.

Some contract language is genuinely ambiguous. “The reading for the week of shipment” and “the reading in effect at the time of pickup” can point to different Mondays for a Tuesday pickup, and a bill that looks wrong under one reading is exactly right under the other. When the clause is that loose, the audit can flag the exposure and recommend the fix, but it cannot always call the line an overcharge. That is a contract problem, not a billing problem, and the fix is in the next negotiation.

How Eller Audit handles this

We keep a complete EIA history, national and all five PADD regions, for every Monday in the audit window, and the current and prior versions of each carrier's surcharge table. Every fuel line on every invoice is reverse-calculated from the contract's named index, anchor date, table, and base, then compared to the billed amount. Variances are grouped by failure mode so the dispute goes to the carrier as one documented pattern with the readings attached, not as a thousand $4 line items. Recoveries are performance-based: you pay a share of what comes back, and nothing on lines that hold up. The first audit is free.

Frequently asked questions

What is a fuel surcharge in freight?

A fuel surcharge is a separate line on a freight bill that adjusts the linehaul rate for the current price of diesel. It is calculated from a public index, almost always the EIA weekly retail diesel price, run through a table or formula in the carrier's tariff or your contract. It is a pass-through in principle; in practice the table, the base it applies to, and the week it is read from are all negotiable and all get misapplied.

How is a fuel surcharge calculated?

Three inputs: an index reading, a table or formula, and a base. LTL and parcel carriers convert the EIA diesel reading into a percentage from a published table and apply it to the discounted linehaul. Truckload carriers use a per-mile formula: (index price minus a peg price) divided by miles per gallon. Rail carriers use a per-mile or per-car scale above a strike price. In every mode the audit reverses the calculation from those three inputs and compares it to the invoice line.

Where do I find the current diesel index?

At eia.gov, in the Weekly U.S. No 2 Diesel Retail Prices series. The EIA publishes it every Monday afternoon (Tuesday when Monday is a federal holiday) as a national average plus regional PADD subsets. Your contract should say which one applies and which week's reading governs a given pickup date.

Is the fuel surcharge applied before or after the discount?

It should be applied to the net linehaul, after the discount. That is the standard structure in LTL and parcel contracts. Applying the surcharge percentage to the gross tariff rate before the discount is one of the largest single fuel errors we find, because it can more than triple the surcharge dollars on a heavily discounted shipment.

Should the fuel surcharge apply to accessorial charges?

Not unless your contract explicitly says so. Fuel surcharge compensates the carrier for diesel burned moving the freight, and accessorials (liftgate, residential delivery, inside delivery, detention) are not mileage. Most contracts limit the surcharge to the linehaul rate; carrier billing systems frequently apply it to the whole invoice anyway.