How Does a Fuel Surcharge (FSC) Work — and How Do You Verify It?

By Erkan Ozturk — owner-operator, HAWD Trucking LLC (USDOT 4436030), Chattanooga TN · Last updated July 11, 2026

What is a fuel surcharge and how is it calculated?

A fuel surcharge exists because diesel moves faster than contracts do. Instead of renegotiating the rate every time the pump changes, the FSC ties one slice of your pay to a published diesel price: when diesel rises, the surcharge rises with it; when diesel falls, so does the surcharge. The standard formula has exactly three inputs, and every one of them is a contract term — not a law of nature.

FSC per mile = (current diesel price − peg price) ÷ divisor MPG

Here is the whole calculation at this week’s real diesel price, using a $1.25 peg and a 6.0 divisor as the example terms. Yours will differ — that is the point of this page.

That $0.55 rides on top of the linehaul rate as a separate line. It is not a bonus and it is not the whole fuel bill — it is the part of your fuel cost the contract agrees to float with the market. What the peg and the divisor each mean is where most of the confusion lives, so take them one at a time.

What do the peg price and the divisor MPG actually mean?

The peg price is the diesel price assumed to be already inside your base rate. Below the peg, no surcharge accrues — the linehaul rate is supposed to be carrying that much fuel on its own. At a $1.25 peg and a 6.0 divisor, the base rate is carrying $1.25 ÷ 6.0 = $0.2083 per mile of fuel, and the surcharge carries everything above it. Check the arithmetic: $0.2083 baked in plus the $0.5547 surcharge equals $0.7630 per mile — exactly $4.578 ÷ 6.0, the full pump price spread over the divisor’s miles. The two pieces always sum back to the whole; the peg only decides how the whole is split between base rate and surcharge.

The divisor MPG is the fuel economy the formula pretends the truck gets. It is not measured from your truck — it is written into the schedule, and it decides how many miles each gallon of price movement is spread across. A truck that actually runs better than the divisor keeps the difference; a divisor set above your real MPG quietly hands it back. For scale, NACFE’s Fleet Fuel Study measured a 7.77 MPG average across its participating fleets for 2023, against a national average near 6.9 — so where a schedule sets its divisor relative to numbers like those is worth reading twice.

How can a fuel surcharge be tuned against you?

None of this requires suspicion — contracts genuinely differ, and a schedule that looks unusual may simply be old. But the same three inputs that make the formula work are also the three places where value can quietly move, and each one shifts it in the same direction. Here is each dial turned once, starting from the $0.5547 example above:

Notice the pattern: a higher peg, an index that reads lower, and a higher divisor all shrink the surcharge — and none of them changes the number printed largest on the rate confirmation. A $36 difference on one load is easy to shrug off; the same divisor applies to every load, every week. The protection is not distrust. The protection is the math: three inputs you can read, one formula you can run, one published price you can check it against.

How do you verify a fuel surcharge, step by step?

Verification is four reads and one division, and after the first time it takes about two minutes a week. First, find the index: the FSC clause should name a published price series — commonly the EIA weekly U.S. on-highway diesel average — and say whether it uses the national or a regional number, and which week’s. Second, find the peg price: a fixed dollar figure. Third, find the divisor MPG: another fixed figure. Fourth, each week, take the published index price and recompute (index − peg) ÷ divisor yourself, then compare it to the FSC line on your settlement.

The mileage basis deserves its own sentence. Many of the numbers on this page were computed on 458 loaded miles, but your diesel does not know the difference between a loaded mile and an empty one — repositioning burns fuel at exactly the same rate. If the surcharge pays on loaded miles only, the deadhead fuel comes out of the linehaul rate, which is one more reason to know how much deadhead miles really cost before you price a load.

How does the surcharge compare to your truck’s real fuel cost?

The formula’s divisor and your truck’s real MPG are two different numbers, and the gap between them is money — in either direction. Your true fuel cost per mile is simply the pump price divided by your real fuel economy; the mechanics get their own page in how do I calculate fuel cost per mile for a truck? Here is what this week’s diesel costs per mile at four fuel economies:

Read that table against the split from earlier: at the example terms, peg-level fuel in the base rate plus the surcharge add up to $0.76 per mile — the full pump price at the 6.0 divisor. A truck that really runs 7.5 MPG spends $0.61. The 15 cents between those numbers is margin your fuel discipline earned, and it only shows up if you know both numbers. On a dated, real example — July 11, 2026, Erie, PA through Buffalo, NY to Boston, MA, 458 loaded plus 93 deadhead miles at 7.5 MPG and EIA diesel of $4.578 — the actual fuel bill is about $336 across all 551 miles, while the example FSC pays $254.05 on the loaded miles alone. The difference is not a scandal; it is the peg-level fuel the base rate is supposed to be carrying. Whether that base rate actually carries it is a question for your floor — how do I calculate my break-even rate per mile?

LoadWizz doesn’t model FSC line items — it prices fuel from the same EIA weekly index at your truck’s real MPG, so you can check any surcharge against your true fuel cost. The surcharge math itself needs nothing but the contract, this week’s published price, and one division — and the rest of the numbers a load runs on live in the Learn library.