What EIA's $6.276 diesel average means for a per-mile fuel surcharge

The Energy Information Administration put the U.S. on-highway diesel average at $6.276 a gallon for the week of Oct. 19, up 9.7 cents from $6.179 the week before, according to EIA's weekly diesel table. The same table puts the price $2.656 above a year ago. EIA's next release is due Oct. 27.

For most truckload contracts, that number is the input to the fuel surcharge. Here is how the math works and how much one week of movement is worth.

The basic formula

Most per-mile surcharges follow the same pattern, as laid out in Dashdoc's fuel surcharge guide (Aug. 15, 2025): current diesel price, minus a base price, divided by the truck's miles per gallon. Dashdoc says contracts pick the base in different ways. Some use a flat industry-standard figure of $1.25 to $1.50 a gallon, some use a rolling 12-month average, and some use the EIA price on the day the contract was signed.

The examples below use Dashdoc's 6.5 mpg worked-example figure and two sample bases. These are illustrations, not anyone's actual contract terms.

- $1.25 base: ($6.276 - $1.25) / 6.5 gives about 77 cents a mile. A 500-mile load carries roughly $387 in surcharge.
- $2.50 base: ($6.276 - $2.50) / 6.5 gives about 58 cents a mile, or roughly $291 over 500 miles.

What a week and a year are worth

The 9.7-cent weekly rise adds about 1.5 cents a mile at 6.5 mpg, or about $7 on a 500-mile load. That is small on one shipment and real across a fleet.

The year-over-year move matters more. EIA's table implies a diesel price of about $3.62 a year ago. On the $1.25 base, that works out to about 36 cents a mile then versus 77 cents now. A carrier or broker still quoting last year's surcharge assumption is short by roughly 41 cents a mile.

What carriers should check

Look at which dataset the contract names. EIA publishes a national average and regional ones. For the week of Oct. 19, EIA shows the West Coast at $7.394 and California at $8.242. At 6.5 mpg, the West Coast figure alone is about 17 cents a mile above what the national average produces. A contract tied to the national number under-recovers in those markets.

Dashdoc also flags timing and mileage. Prices are weekly while pump prices move daily, and the contract should say which week's reading applies. It should also say whether the surcharge is paid on loaded miles only, since deadhead miles burn fuel too.

What shippers and brokers should watch

Check the base price first, because a lower base means a larger surcharge at the same pump price. Then confirm the mpg assumption and whether caps or floors exist. Dashdoc recommends using the fleet's actual average mpg instead of an industry estimate.

Tuesday's EIA reading sets the next surcharge step for many contracts. For current prices by state, see PDI's diesel page at /diesel.