Idaho vs Utah gas prices
Regular gas is $0.06 a gallon cheaper in Utah — $0.86 on a 15-gallon fill-up. The two share a border, so that gap is worth knowing before you cross it.
Idaho
Utah| Grade | ID | UT | Diff. | |
|---|---|---|---|---|
| Regular | $4.31 | $4.25 | $0.06UT | Utah |
| Midgrade | $4.60 | $4.54 | $0.06UT | Utah |
| Premium | $4.87 | $4.80 | $0.07UT | Utah |
| Diesel | $5.32 | $5.28 | $0.03UT | Utah |
Where the $0.06 gap actually comes from
None of it is tax. This is the case people assume never happens: Idaho is dearer at the pump while taxing a gallon $0.04 less than Utah. The whole gap is the cost of the fuel itself — refinery proximity, pipeline access and state blend rules — and the tax difference is quietly shrinking it.
Fuel, refining, distribution and marginFederal and state taxes Pre-tax figures are estimates — see the note below.
What the gap is worth
Based on today’s $0.06 per-gallon difference, which moves week to week. Use the fuel cost calculator for your own mileage and vehicle.
Prices by metro area
State averages hide a lot. These are the cheapest metros AAA reports on each side.
Other comparisons
Frequently asked questions
Is gas cheaper in Idaho or Utah?
Regular gas is cheaper in Utah, at $4.25 a gallon against $4.31 in Idaho — a gap of $0.06, or 1.3%. On a 15-gallon fill-up that is $0.86. Figures are AAA daily state averages for 2026-08-02.
Why is gas more expensive in Idaho?
Not because of tax — Idaho actually levies $0.04 a gallon less than Utah. The whole $0.06 gap, and more, is the cost of the fuel itself: refinery proximity, pipeline access and state fuel-blend rules. Tax policy is narrowing this gap rather than causing it.
Is diesel cheaper in Idaho or Utah?
Diesel is cheaper in Utah at $5.28 a gallon, against $5.32 in Idaho — $0.03 a gallon apart.
Is it worth crossing from Idaho into Utah to fill up?
If you are already near the line, yes: a 15-gallon fill saves about $0.86. Driving out of your way for it rarely pays — at $4.31 a gallon and 25 mpg, a 2-mile round trip would eat the whole saving in fuel alone, before your time.