List of U.S. states by standard octane ratings explained

Most states do not mandate certain standard gasoline grade octane ratings. In the United States and Canada, octane ratings are in AKI, commonly shown as "(R+M)/2". All states require gas pumps to be labeled with the correct octane level and nearly all states do regular testing to make sure gas stations are in compliance. A minimum 82 octane fuel is recommended for most vehicles produced since 1984. Older cars with carburetors could operate with lower octane fuel at higher elevations. Regardless of legality fuel with an octane rating of less than 82 is generally not offered for sale in most states. However 85 and 86 octane gasoline can still commonly be found in several Rocky Mountain states but availability is declining due to fewer cars with carburetors being still on the road and they are already gone in many states that previously sold it like Alaska, Maine and North Dakota.

State Octane Ratings

The octane ratings below are the lowest allowed by law and may or may not reflect the actual levels offered for sale at most gas stations. Ethanol's effect on octane is not considered—these are ratings that are seen at the pump.

State	Regular Unleaded	Mid-Grade Unleaded	Premium Unleaded	Notes
Alabama	87	89	93
Alaska	87	88.5	90
Arizona	87	89	91
Arkansas	87	89	91/93	Northwest Arkansas primarily sells 87/89/91 octane. 93 octane is available at select Kum & Go's in the Northwest and Central regions of the state.
California	87	89	91
Colorado	85	87	91
Connecticut	87	89	93	86 octane may be sold if labeled as economy^[1]
Delaware	87	89	93
Florida	87 ^[2]	89	93	91 octane premium is sold at select stations alongside 93 octane.
Georgia	87 ^[3]	89	93
Hawaii	87	89	92
Idaho	85/87	87/89	91	Octane ratings in Eastern Idaho are 85/87/91 in Western Idaho the octane ratings are 87/89/91.
Illinois	87 ^[4]	89	91	93 is widely available in the Chicago area. Elsewhere in Illinois, 93 is offered at Shell and select other stations. Many fuel stations now offer an 88-octane fuel blend that is 15% ethanol, suitable for use in some gasoline-powered automobiles from model year 2001 and newer.
Indiana	87	89	93
Iowa	87	89	91	Many stations will offer "Super Unleaded" 87 that contains 10% ethanol and a more expensive "Unleaded" 87 with no ethanol. 93 is available at select Kum & Go and Murphy USA / Walmart locations.
Kansas	87	89	91	All BP Stations offer 93 octane gasoline
Kentucky	87 ^[5]	89	93
Louisiana	87	89	93
Maine	87	89	91 without ethanol 93 with ethanol	Premium gas must be at least 93 octane if it contains 10% or more of ethanol
Maryland	87	89	93
Massachusetts	87	89	93
Michigan	87	89	93	85 and 86 octane may be sold if labeled as subregular^[6]
Minnesota	87	89	91	110 octane fuel may be available at certain locations in southern parts of the state.
Mississippi	87	89	93
Missouri	87	89	91/93	Some Phillips 66, Break Time, and Conoco stations sell 91 octane premium. Southwest Missouri in the Ozark Mountains and Mark Twain primarily only sell 87/89/91
Montana	85.5 ^[7]	88	91
Nebraska	87	89	91
Nevada	87	89	91	Eastern Nevada primarily uses 85/87/91 octane ratings.
New Hampshire	87	89	93
New Jersey	87	89	93	New Jersey checks for fraudulent labeling of octane ratings.^[8]
New Mexico	86	88	91
New York	87 ^[9]	89	91/93	93 is widely available.
North Carolina	87	89	93	91 octane is commonly sold as "premium" in the western, mountainous part of the state.
North Dakota	87 ^[10]	89	92
Ohio	87	89	93
Oklahoma	87	89	91
Oregon	87	89	92
Pennsylvania	87	89	93
Rhode Island	87	89	93
South Carolina	87	89	93	lower octane gas can be sold if labeled as "sub-standard" or "sub-regular"^[11]
South Dakota	85/87	87/89	91	85 octane must be sold with a warning label displayed at the pump.^[12] 85 and 86 octane can be sold as regular fuel only in the counties of Butte, Custer, Fall River, Harding, Lawrence, Meade, Oglala Lakota, Pennington, and Perkins.^[13] 87 and 88 can be sold as mid-grade in the previously-named counties.
Tennessee	87	89	93
Texas	87	89	93	El Paso, Lubbock, and Amarillo areas have 86/88/91 octane ratings.
Utah	85	88	91
Vermont	87	89	93
Virginia	87	89	93
Washington	87	89	92
West Virginia	87	89	93
Wisconsin	87	89	91	93 widely available
Wyoming	85	88	91

Notes and References

1. Web site: Connecticut Department of Consumer Protection.
2. Florida Administrative Code 5F-2
3. Web site: Fuel & Measures FAQs - Ga Dept of Agriculture.
4. Web site: Motor Fuel and Petroleum Standards Act. Illinois General Assembly.
5. http://www.lrc.state.ky.us/kar/302/079/010.htm
6. Web site: Motor Fuels Quality Act of 1984. https://web.archive.org/web/20211205115431/https://www.legislature.mi.gov/(S(kvnx05fhsdtufphvy1a1ste3))/documents/mcl/pdf/mcl-Act-44-of-1984.pdf. 2021-12-05. Michigan Legislature. 2021-12-02.
7. Web site: Frequently Asked Questions.
8. News: New Jersey Weights and Measures. 7 September 2017. NJ Department of Law and Public Safety.
9. Web site: 2012 New York Consolidated Laws :: AGM - Agriculture & Markets :: Article 16 - (176 - 197-B) WEIGHTS AND MEASURES :: 192-A - Fuel octane labelling requirements.
10. Web site: Article 33-34: Petroleum and Fuel Products. North Dakota Legislative Assembly.
11. Web site: Code of Laws - Title 39 - Chapter 41 - Gasoline, Lubricating Oils and Other Petroleum Products.
12. Web site: South Dakota Legislature.
13. Web site: South Dakota Legislature.