Idaho Gas Prices This Week

In the EIA’s July 2026 (revised August 2026) table of motor fuel taxes, Idaho’s state taxes and fees on gasoline total 33.0¢ a gallon, the 20th-highest of the 50 states and D.C. The 51-jurisdiction average is 33.8¢, and the federal tax adds 18.4¢ everywhere. Idaho’s excise tax is 32¢ a gallon, following a 7¢ increase in July 2015, plus a 1¢ petroleum transfer fee. It is not indexed.

Idaho has no refineries. Its gasoline arrives by pipeline from refineries in Utah and Montana, and the state belongs to the EIA’s Rocky Mountain region. Like its neighbors, Idaho sells regular gasoline at 85 octane rather than 87, which the EIA attributes to the region’s altitude.

Idaho’s annual average has run slightly above the national average for most of the record, with an average gap of 0.9¢ above it in the 1970s, 5.4¢ above in the 1990s, 6.9¢ above in the 2000s, and 11.4¢ above in the 2010s. Its ranking has moved more than the gap suggests, because many states sit within a few cents of each other: Idaho was the 6th-cheapest state in 1971 and 46th in 1975, and ranked between 32nd and 44th in every year from 2000 through 2024. The widest gap before the EIA changed its estimation method was 12.8¢ above the U.S. average, in 2010.

From 2011 on, the EIA has estimated Idaho’s price by applying the Rocky Mountain regional trend to its 2010 level, so Idaho’s yearly changes have matched Montana’s, Utah’s, and Wyoming’s to within a tenth of a point: −26.9% in 2015 and +39.9% in 2021, the largest one-year rise in Idaho’s record. The record annual average is $4.16, in 2022; adjusted for inflation, the high was 2012 ($5.06 in 2025 dollars) and the low 1998.

The Rocky Mountain region has the strongest seasonal pattern the EIA publishes: its weekly price is about 13% below the annual average in January and stays near 7.6% above it from June through September.

Washington, at $4.07, was the bordering state with the highest 2024 average, and Idaho's $3.35 was 72.1¢ below it. Oregon stood at $4.06, with Idaho 71.3¢ below, and Nevada at $3.96, with Idaho 61.1¢ below. Wyoming, at $3.12, had the lowest 2024 average of the bordering states, and Idaho was 22.6¢ above it. Montana and Utah were both at $3.33 in 2024, and Idaho was 1.4¢ above Montana and 1.6¢ above Utah.

Idaho's 2024 rank was 39th-cheapest of the 50 states and D.C., or 13th-most-expensive, against a U.S. average of $3.29. That 2024 average converts to $3.44 in 2025 dollars. Idaho was 44th-cheapest in both 2010 and 2020, after ranking 43rd-cheapest in 2000.

Idaho's years below the U.S. average were 1970–1972, 1974 and 1980, which makes 5 of 55 years, and its gap below peaked at 1.3¢ in 1971. In 1971 it also held its cheapest rank, 6th-cheapest. Its gap above the U.S. peaked at 35.7¢ in 2021, and in 1975 it held its least favourable rank, 46th-cheapest (6th-most-expensive).

Prices at the start of the record were $0.35 in 1970, $1.22 in 1980 and $1.14 in 1990. The 2024 average was 3.0% lower than the 2014 average at the pump. The fall from 2014 to 2024 was 26.8% in constant 2025 dollars. The largest one-year fall was 28.2% in 2009, and the lowest constant-dollar average was $2.23 in 1998.