Freight 5 min read · updated Nov 9, 2026
How trucking fuel surcharges work
Peg price, miles per gallon and the weekly EIA diesel number: the formula behind most truckload surcharges.
Most truckload fuel surcharges use three inputs: a peg (the diesel price already built into the base rate), the truck's assumed miles per gallon, and the weekly EIA U.S. on-highway diesel price.
The common formula is: surcharge per mile = (EIA diesel price − peg) ÷ mpg. With a $1.25 peg and 6.5 mpg, every 10¢ rise in diesel adds about 1.5¢ a mile. Some shippers use the regional price for the lane's origin instead of the national figure.
Try it with this week's prices in the fuel surcharge calculator. Parcel carriers use percentage tables instead; see our sister site ParcelFuelSurcharge.com.