Gas prices in Montana: Rocky Mountain average and state gas tax
There's no official weekly average just for Montana. What there is: the Rocky Mountain regional average, which the state is part of, at $4.46 for regular this week (October 26, 2026). That's +18.9¢ versus the whole country. Taxes are a big part of the story: Montana's state gas tax and fees total 33.8¢ per gallon (19th of 51, highest first), and diesel carries 30.5¢. Since January 2015, the gasoline rate has moved +6.0¢.
The quick take
Crossing a state line can change the tax you pay: next door to Montana, rates run from 23.0¢ in North Dakota to 33.0¢ in Idaho.
Regular gas, weekly average · Rocky Mountain
November 4, 2024: $3.103 · October 26, 2026: $4.458 · min $2.403 · max $4.587
The state's gas tax since 2015
| Rate as of | Gasoline | Diesel |
|---|---|---|
| Jul 2026 | 33.8¢ | 30.5¢ |
| Jan 2026 | 33.8¢ | 30.5¢ |
| Jul 2025 | 33.8¢ | 30.5¢ |
| Jan 2025 | 33.8¢ | 30.5¢ |
| Jul 2024 | 33.8¢ | 30.5¢ |
| Jan 2024 | 33.8¢ | 30.5¢ |
| Jul 2023 | 33.8¢ | 30.5¢ |
| Jan 2023 | 33.8¢ | 30.5¢ |
| Jul 2022 | 33.8¢ | 30.5¢ |
| Jan 2022 | 33.2¢ | 30.3¢ |
| Jul 2021 | 33.2¢ | 30.3¢ |
| Jul 2020 | 32.8¢ | 30.2¢ |
| Jan 2020 | 32.8¢ | 30.2¢ |
| Jul 2019 | 32.8¢ | 30.2¢ |
| Jan 2019 | 32.2¢ | 30.0¢ |
| Jul 2018 | 32.2¢ | 30.0¢ |
| Jan 2018 | 32.2¢ | 30.0¢ |
| Jul 2017 | 32.2¢ | 30.0¢ |
| Jan 2017 | 27.8¢ | 28.5¢ |
| Jul 2016 | 27.8¢ | 28.5¢ |
| Jan 2016 | 27.8¢ | 28.5¢ |
| Jul 2015 | 27.8¢ | 28.5¢ |
| Jan 2015 | 27.8¢ | 28.5¢ |
Neighboring states
Idaho33.0¢North Dakota23.0¢South Dakota30.0¢Wyoming24.0¢
Map
Region: Rocky Mountain · Gas tax by state · Diesel prices · U.S. average