Fuel
$4.049 a gallon
The US retail on-highway average for the week ending August 17, 2026, and the number every calculator on this site opens with. The spread across the country is $1.775 a gallon, which at 6.5 mpg is 27.3 cents a mile depending on nothing but where you filled up.
| Region | This week | Last week | Change | Per mile at 6.5 | Surcharge over $1.25 |
|---|---|---|---|---|---|
| U.S. average | $4.049 | $4.006 | +0.043 | $0.623 | $0.467 |
| East Coast | $3.863 | $3.884 | -0.021 | $0.594 | $0.435 |
| New England | $3.946 | $3.975 | -0.029 | $0.607 | $0.449 |
| Central Atlantic | $4.038 | $4.060 | -0.022 | $0.621 | $0.465 |
| Lower Atlantic | $3.730 | $3.749 | -0.019 | $0.574 | $0.413 |
| Midwest | $3.938 | $3.816 | +0.122 | $0.606 | $0.448 |
| Gulf Coast | $3.622 | $3.543 | +0.079 | $0.557 | $0.395 |
| Rocky Mountain | $4.285 | $4.121 | +0.164 | $0.659 | $0.506 |
| West Coast | $5.086 | $5.075 | +0.011 | $0.782 | $0.639 |
| California | $5.397 | $5.428 | -0.031 | $0.830 | $0.691 |
U.S. Energy Information Administration, weekly retail on-highway diesel, read from eia.gov for the week ending August 17, 2026. Refreshed weekly; every figure on this site that uses a fuel price carries this same date.
Cheap fuel does not beat the fuel tax
You pay fuel tax to the state you burned the fuel in, not the state you bought it in. Buying in a low-tax state defers the tax; it does not avoid it, and IFTA collects the difference at the end of the quarter. What buying cheap fuel actually saves is the difference in the rack price, which is what this table shows.
The surcharge is calculated on someone else’s mpg
A fuel surcharge is usually the current price minus a pegged base, divided by an ASSUMED 6.0 mpg. A truck doing 7.5 keeps the difference; a truck doing 5.5 pays it. And a surcharge paid on loaded miles only does not cover the fuel burned getting to the load.
What the spread is worth
California is $1.775 a gallon over Gulf Coast this week. Over 120,000 miles at 6.5 mpg that is $32,769, which is why fuel routing is a real job rather than a habit.