How to Calculate a Trucking Fuel Surcharge

A fuel surcharge pays you back when diesel costs more than your rate was built for. Your linehaul rate covers fuel up to a set price. Above that, the surcharge makes up the difference, one mile at a time. When diesel jumps, it's often the only thing standing between a load that pays and one that doesn't.

The formula

Surcharge per mile = (current diesel price − base price) ÷ MPG.

Surcharge for the load = surcharge per mile × miles.

• Current diesel price is usually the weekly on-highway diesel average from the U.S. Energy Information Administration (EIA). EIA is part of the Department of Energy, which is why people call it the "DOE price." Your contract says whether to use the U.S. average or a region, and which week counts.
• Base price (sometimes called the peg) is the diesel price your linehaul rate already covers. It's a number in your contract. There's no official one.
• MPG is also set in the contract. It may not match your truck. If the contract says 6 MPG and you get 7, you come out a little ahead when diesel is high. If you get 5.5, you come out behind.

Where the weekly price comes from

EIA publishes retail on-highway diesel prices every week for the U.S. and for regions: the East Coast (split into New England, Central Atlantic, and Lower Atlantic), Midwest, Gulf Coast, Rocky Mountain, and West Coast, with California and the West Coast outside California shown separately. The prices are in dollars per gallon and include taxes.

Each week is dated by its Monday. The prices for the week of September 21, 2026 came out on September 22, and EIA listed September 29 as the next release, according to its Gasoline and Diesel Fuel Update. Our weekly fuel surcharge pages have every week for the last two years, by region.

Worked example with this week's price

Say your contract has a $2.50 base and 6 MPG, uses the U.S. average, and the load is 850 miles. EIA's U.S. average for the week of September 21, 2026 was $6.529 a gallon.

1. Price above the base: $6.529 − $2.50 = $4.029 a gallon.
2. Surcharge per mile: $4.029 ÷ 6 = $0.6715, which rounds to $0.672 a mile.
3. Surcharge for the load: $0.672 × 850 = $571.20.

Now look back a year. For the week of September 22, 2025, the U.S. average was $3.749. Same contract, same load: ($3.749 − $2.50) ÷ 6 = $0.208 a mile, or $176.80 for 850 miles. The same run pays $394.40 more in surcharge this week, because diesel is $2.78 a gallon higher.

Region matters

If your contract uses a regional price instead of the U.S. average, the same load can pay quite differently. Week of September 21, 2026, $2.50 base, 6 MPG, 850 miles:

• Gulf Coast at $6.177: $0.613 a mile, $521.05 for the load.
• U.S. average at $6.529: $0.672 a mile, $571.20.
• Midwest at $6.680: $0.697 a mile, $592.45.
• California at $8.246: $0.958 a mile, $814.30.

Check your rate con for which price is used. If it doesn't say, ask before you sign.

When diesel drops below the base

The formula goes negative when diesel is cheaper than the base price. The lowest weekly U.S. average in the last two years was $3.451, for the week of June 2, 2025. With a $3.50 base, that works out to ($3.451 − $3.50) ÷ 6 = −$0.008 a mile. Most schedules pay $0 in that case, and our calculator does the same by default. Some contracts credit the difference back to the shipper, so there's a box to allow a negative surcharge if yours does.

Reading a surcharge table

Many shippers hand you a table instead of a formula. Each row is a price band, like $6.50 to $6.549, with one surcharge per mile for anything in that band. The table is the same formula worked out ahead of time, usually at the low end of each band. Our calculator builds that table for your base and MPG, in 5¢ or 10¢ steps, and marks the row for the current price. If a shipper's table doesn't match the formula at their own base and MPG, ask why.

Things to check on every load

• Which week. The week the load picks up, the week it delivers, or the week it was booked can each give a different price.
• Which miles. Loaded miles only, or all miles. Surcharge on loaded miles only doesn't cover the fuel you burn deadheading.
• All-in rates. A rate quoted "all in" already includes fuel. Back out the surcharge to see what the linehaul really pays.
• Your real fuel cost. The surcharge is built on an average price and a contract MPG. Run the trip fuel cost calculator with your own MPG and pump price to see if it actually covers you.

Then plug the full rate, surcharge included, into the load profit calculator to see if the load is worth it.