Idaho · week of September 21, 2026
Gas prices in Idaho: Rocky Mountain average and state gas tax
Looking for gas prices in Idaho? The official weekly data stops at the regional level here. The Rocky Mountain average for regular is $4.51 (September 21, 2026), which runs +3.2¢ compared with the U.S. average. How much of the price is tax? In Idaho, state taxes and fees on gasoline add up to 33.0¢ a gallon, and the federal excise brings the total to 51.4¢, about 11% of the weekly average.
regional average · Rocky Mountain
$4.510
EIA weekly survey
$4.510regional average · Rocky Mountain
+7.2¢change in a week
+$1.33change in a year
$6.340diesel
33.0¢state gas tax + fees
51.4¢state + federal tax
20th / 51rank for gas tax
The quick take
Among the 6 states that border Idaho, Nevada has the lightest gas tax at 23.8¢ a gallon and Washington the heaviest at 60.2¢.
Regular gas, weekly average · Rocky Mountain
September 30, 2024: $3.415 · September 21, 2026: $4.510 · min $2.403 · max $4.587
The state's gas tax since 2015
| Rate as of | Gasoline | Diesel |
|---|---|---|
| Jul 2026 | 33.0¢ | 33.0¢ |
| Jan 2026 | 33.0¢ | 33.0¢ |
| Jul 2025 | 33.0¢ | 33.0¢ |
| Jan 2025 | 33.0¢ | 33.0¢ |
| Jul 2024 | 33.0¢ | 33.0¢ |
| Jan 2024 | 33.0¢ | 33.0¢ |
| Jul 2023 | 33.0¢ | 33.0¢ |
| Jan 2023 | 33.0¢ | 33.0¢ |
| Jul 2022 | 33.0¢ | 33.0¢ |
| Jan 2022 | 33.0¢ | 33.0¢ |
| Jul 2021 | 33.0¢ | 33.0¢ |
| Jul 2020 | 33.0¢ | 33.0¢ |
| Jan 2020 | 33.0¢ | 33.0¢ |
| Jul 2019 | 33.0¢ | 33.0¢ |
| Jan 2019 | 33.0¢ | 33.0¢ |
| Jul 2018 | 33.0¢ | 33.0¢ |
| Jan 2018 | 33.0¢ | 33.0¢ |
| Jul 2017 | 33.0¢ | 33.0¢ |
| Jan 2017 | 33.0¢ | 33.0¢ |
| Jul 2016 | 33.0¢ | 33.0¢ |
| Jan 2016 | 33.0¢ | 33.0¢ |
| Jul 2015 | 33.0¢ | 33.0¢ |
| Jan 2015 | 26.0¢ | 26.0¢ |
Neighboring states
Montana33.8¢Nevada23.8¢Oregon40.0¢Utah38.6¢Washington60.2¢Wyoming24.0¢
Map
$3.972$4.539$5.106
Regular gas
Region: Rocky Mountain · Gas tax by state · Diesel prices · U.S. average