Fuel surcharge
Work out what the surcharge on a load should be, using this week's actual diesel price for your region. Free, and nothing is stored.
Prices for the week to 17 August 2026
| Surcharge on 500 miles | $323.38 |
| Fuel you will burn | 76.9 gal |
| What that fuel costs at national average prices | $419.54 |
The standard formula, and the one nearly
every contract uses:
(diesel price − base price) ÷ miles per gallon
The surcharge is meant to cover the
difference between fuel now and fuel when the rate was agreed —
it is not meant to cover all of your fuel. If the surcharge alone
covers the whole bill, the base price in your contract is doing
something unusual.
National average diesel
A fuel surcharge exists because nobody can price a year of freight against a fuel price that moves every week. The rate covers the haul; the surcharge covers the gap between diesel today and diesel at the price both sides agreed to when they signed.
Three numbers set it. The base price is the diesel price baked into your rate — below it, no surcharge is owed. The current price is normally the Energy Information Administration's weekly survey, published every Monday, which is what the figures above are. And your fuel economy converts dollars per gallon into dollars per mile.
Two things worth checking in your own contract. First, which price it names: the national average and a regional one can differ by thirty cents or more, and over a long haul that is real money. Second, which week: most contracts use the previous Monday's figure, so a surcharge lags the pump by up to a week in both directions.
The EIA figure is a retail pump average including taxes. Fleets buying on contract at truck stops generally pay less than it, and the gap widens when prices move quickly.