Montana Gas Prices This Week

In the EIA’s July 2026 (revised August 2026) table of motor fuel taxes, Montana’s state taxes and fees on gasoline total 33.8¢ a gallon, the 19th-highest of the 50 states and D.C. The 51-jurisdiction average is 33.8¢, and the federal tax adds 18.4¢ everywhere. Montana’s excise tax is 33¢ a gallon after a 2017 law raised it in steps through 2023. A petroleum storage tank cleanup fee of 0.75¢ is added, and the EIA notes that local option taxes are allowed.

Montana is a refining state. The EIA lists four refineries with about 210,000 barrels a day of capacity: two in Billings (Phillips 66 and Par Montana), one in Laurel (CHS), and one in Great Falls (Calumet). They supply Montana and send gasoline by pipeline to neighboring states. As elsewhere in the Rocky Mountain region, regular gasoline is sold at 85 octane.

In-state refining has not put Montana below the national average. Its annual average was within two cents of the U.S. figure in 14 of the 17 years from 1970 through 1986, then settled above it, by an average of 9.4¢ in the 1990s, 8.2¢ in the 2000s, and 10.0¢ in the 2010s. Montana ranked between 41st and 47th in every year from 1993 through 2002. Its widest gap before 2011 was 13.8¢ above the U.S. average, in 1997. In the 1970s it ranked as low as 14th-cheapest (1972), and as high as 49th (1978).

Since 2011, the EIA has estimated Montana’s annual price by applying the Rocky Mountain regional trend to its 2010 level, so its year-to-year changes since then match Idaho’s, Utah’s, and Wyoming’s. The largest rise in Montana’s record came in 2021 (+39.9%), and the largest declines in 2009 (−27.4%) and 2015 (−26.9%). The record annual average is $4.14, in 2022; adjusted for inflation, the high was 2012 ($5.04 in 2025 dollars).

Montana’s region has a long summer peak: the Rocky Mountain weekly price stays about 7.6% above its annual average from June through September, after a January low about 13% below.

Montana's 2024 annual average of $3.33 ranked 36th-cheapest among the 50 states and D.C., which is 16th-most-expensive counted from the other end. The U.S. average on the same basis was $3.29 in 2024, and Montana averaged 4.5¢ above it. In constant 2025 dollars, Montana's 2024 figure was $3.42.

Among the states that border Montana, Idaho had the highest 2024 average at $3.35, and Wyoming had the lowest at $3.12. Montana averaged 1.4¢ below Idaho in 2024. It averaged 1.7¢ above North Dakota ($3.31), 10.0¢ above South Dakota ($3.23) and 21.2¢ above Wyoming, so 3 of 4 bordering states averaged less than Montana that year.

Three years from 1970 to 2024 had Montana's average below the U.S. average: 1972, 1974 and 1986. The other 52 of 55 years had it above. In 2021 Montana averaged 34.3¢ above the U.S., the largest amount in any year of that span. Its rank moved from 30th-cheapest in 1970 ($0.36) to 47th-cheapest in 2000 ($1.61), then stood at 41st-cheapest in 2010 ($2.85) and 43rd-cheapest in 2020 ($2.37). Measured in 2025 dollars, the lowest annual average came in 1998 at $2.29.