Idaho vs Utah gas prices
Regular gas is $0.04 a gallon cheaper in Idaho — $0.53 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 | $4.14 | $4.17 | $0.04ID | Idaho |
| Midgrade | $4.47 | $4.46 | $0.00UT | Utah |
| Premium | $4.73 | $4.71 | $0.02UT | Utah |
| Diesel | $6.21 | $6.17 | $0.04UT | Utah |
Is cheaper gas worth the detour?
Use your tank and extra travel costs. Prices below are AAA state averages as of 2026-11-13; check the actual station prices before driving.
Extra distance and time include the return to your original route. Detour fuel uses the higher state price. Tire wear and maintenance are excluded. This estimates a price difference; it does not verify a station offer or route.
Where the $0.04 gap actually comes from
All of it is tax, and then some. The fuel itself is dearer in Idaho before tax — by $0.00 a gallon — yet it is still $0.04 cheaper at the pump, because Utah levies $0.04 more per gallon. Policy is doing all of the work here and overcoming a product disadvantage on the way.
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 $0.04 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 Idaho, at $4.14 a gallon against $4.17 in Utah — a gap of $0.04, or 0.8%. On a 15-gallon fill-up that is $0.53. Figures are AAA daily state averages for 2026-11-13.
Why is gas more expensive in Utah?
Entirely because of tax. Idaho actually pays more for the fuel itself — $0.00 a gallon more before tax — but Utah levies $0.04 more per gallon, which more than reverses the advantage.
Is diesel cheaper in Idaho or Utah?
Diesel is cheaper in Utah at $6.17 a gallon, against $6.21 in Idaho — $0.04 a gallon apart. Note that this is the opposite way round from regular gas, because the two states tax the two fuels differently.
Is it worth crossing from Utah into Idaho to fill up?
If you are already near the line, yes: a 15-gallon fill saves about $0.53. Driving out of your way for it rarely pays — at $4.17 a gallon and 25 mpg, a 2-mile round trip would eat the whole saving in fuel alone, before your time.
Why this price is what it is
- Premium vs. Regular Gas: Is Premium Actually Worth It?Premium costs more per gallon — but does it help your car? Here's when premium is worth it, when it's wasted money, and what octane really does.
- Fuel Taxes Explained: What You Really Pay Per GallonA big slice of every gallon is tax — but how much, and where does it go? A clear guide to federal, state and European fuel taxes.
- The Best Day and Time to Buy Gas (Backed by Price Data)Studies of billions of transactions point to early in the week as the cheapest time to fill up. Here's the best day, the best time of day, and why it works.