Updated October 2026
The formula
A fuel surcharge passes the part of the fuel bill above an agreed base price on to the customer. The base, or peg, is the fuel price already built into the linehaul rate. Anything above it gets billed per mile.
Surcharge per mile = (current price − base price) ÷ MPG
Metric: (current − base) × L/100 km ÷ 100 gives the surcharge per km.
The division by MPG is what turns a price per gallon into a price per mile: a truck doing 6.5 MPG burns 1 ÷ 6.5 = 0.154 gallons every mile, so each dollar above the peg costs 15.4 cents a mile.
Surcharge schedule
Carriers usually publish this as a table. Here is one with a $1.25 peg, in dollars per mile, for the three MPG figures that show up most in contracts:
| Diesel, $/gal | 6.0 MPG | 6.5 MPG | 7.0 MPG |
|---|---|---|---|
| 3.00 | 0.292 | 0.269 | 0.250 |
| 3.25 | 0.333 | 0.308 | 0.286 |
| 3.50 | 0.375 | 0.346 | 0.321 |
| 3.75 | 0.417 | 0.385 | 0.357 |
| 4.00 | 0.458 | 0.423 | 0.393 |
| 4.25 | 0.500 | 0.462 | 0.429 |
| 4.50 | 0.542 | 0.500 | 0.464 |
The rule of thumb that falls out of it: at 6 MPG, every 6 cents on the price of diesel adds a penny a mile. At 6.5 MPG it is every 6.5 cents. That is the whole schedule, compressed.
Worked example
A 500 mile load at $2.50 a mile linehaul, $1.25 peg, diesel at $3.75, contract MPG of 6.5:
| Step | Working | Result |
|---|---|---|
| Price above peg | $3.75 − $1.25 | $2.50/gal |
| Surcharge per mile | $2.50 ÷ 6.5 | $0.385 |
| Surcharge on the load | $0.3846 × 500 | $192.31 |
| As % of linehaul | $0.3846 ÷ $2.50 | 15.4% |
| Invoice total | $1,250 + $192.31 | $1,442.31 |
The truck burns 76.9 gallons on that run, $288.46 at $3.75. The surcharge covers $192.31 of it and the linehaul covers the rest at the peg price. That is the deal working as designed.
Vans, pickups and couriers
The formula does not care what the vehicle is. A courier in a cargo van doing 18 MPG on gas at $3.40, with a $2.00 peg, has a surcharge of $1.40 ÷ 18 = 7.8 cents a mile. A hotshot pickup pulling a gooseneck at 11 MPG is in between.
What matters there is using a real MPG rather than the sticker figure. A van loaded to the roof does not get its EPA rating, and a surcharge built on the brochure number leaves money on the table every mile. Measure it over a few tanks with the gas mileage calculator, and check the whole running cost with the cost per mile calculator before you set rates.
Questions people actually ask
How is a fuel surcharge calculated? +
What base price should I use? +
Where does the current diesel price come from? +
What MPG goes in the formula? +
Per mile or a percentage of the rate? +
Keep going
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Mileage reimbursement calculator
IRS 2026 rates, both halves of the year, and whether the check covers your gas.