In the United States, premium gasoline is commonly 93 octane on the AKI scale, though some areas label 91 as premium. The exact grade can vary by brand and location.
What octane means and how it’s measured
Octane is a fuel’s resistance to knocking (pre-ignition) in an engine. In North America, octane is reported as AKI (Anti-Knock Index), which is roughly the average of Research Octane Number (RON) and MON. In Europe and many other regions, octane is reported as RON, and a separate MON is used to derive the AKI-equivalent. Higher octane fuels resist knocking and can be required for high-compression or turbocharged engines. Using an octane grade lower than what the manufacturer recommends can cause knocking and potential damage; using a higher grade than required typically provides no performance benefit unless the engine is knocking or designed for it.
Note that labeling varies by region and brand, so it’s best to rely on your vehicle’s owner’s manual and the pump label. The rest of this article breaks down regional differences and practical advice for choosing the right grade.
Before diving into regional differences, here’s a quick heads-up: premium labeling is not universal. The numbers you see on pumps reflect local standards, and many cars only need the octane specified by the manufacturer. The following sections explain how this plays out in different markets.
Regional labeling and what counts as premium in different markets
- United States and Canada: Premium is most commonly 93 AKI, but some areas sell 91 AKI as premium. Regular is typically 87 AKI; mid-grade 89 AKI exists at certain brands, and availability of 93 can vary by station.
- Europe and the UK: Premium is typically 95–98 RON, which is a different scale from AKI. Direct one-to-one comparisons between AKI and RON are not exact, but European premium is generally higher in the RON scale.
- Other regions: Premium octane varies widely (for example, 92–94 RON in some markets; 91–93 AKI in others). Always check the local pump labeling and your vehicle’s recommendations.
Concluding: In practice, the exact premium grade you’ll encounter depends on where you refuel and which brand you choose. Use the octane level your car requires, as specified in the owner’s manual, and don’t assume that higher-octane fuel will boost performance unless your engine specifically calls for it.
Choosing the right octane for your car
To determine the right octane, follow these steps and rely on official guidance from the manufacturer. The goal is to prevent knocking and maintain efficiency, not to chase a universal “best” number.
- Check the owner’s manual for the recommended octane. Some engines require premium; others run fine on regular or mid-grade.
- Listen for knocking or pinging under load with the current grade. If you hear knock, try the higher grade if recommended.
- Understand that higher octane isn’t a guaranteed performance boost. If the manual doesn’t require it, you may not gain power or efficiency from premium fuel.
- Read the pump label carefully: “Premium” will indicate the highest octane available at that location, but the exact number can vary by region and brand.
Concluding: Following the manufacturer’s octane requirements ensures optimal performance and longevity. Higher-octane fuel is most beneficial for engines designed to take advantage of it or prone to knocking when using lower grades.
Summary
Premium gas is not universally fixed at 91 or 93. In the United States, premium is typically 93 AKI, with some stations in certain regions offering 91 AKI as premium. In Europe, premium usually runs 95–98 RON, and Canada commonly uses 91–93 AKI depending on the province and station. Always use the octane grade recommended by your vehicle’s manual, and read the pump labeling to identify the exact grade you are purchasing. Higher-octane fuels do not inherently improve fuel economy or performance unless the engine requires them or is experiencing knocking.
Is 91 regular or premium?
regular unleaded petrol
91 RON: regular unleaded petrol
It's formulated for engines with lower compression, so it ignites more easily at lower temperatures and pressures than higher‑octane fuels. It's also usually the cheapest fuel option. Most modern cars built to run on 91 will operate reliably and efficiently on this fuel.
Is Costco gas 91 or 93?
For Costco gas, premium gasoline is typically rated at 91 Octane. That rating is, in fact, the only difference between regular and premium gasoline.
Who has the highest gas prices in the United States?
As of April 15, 2026, the highest average gas price nationwide was in California ($5.88 per gallon), followed by Hawaii ($5.65) and Washington ($5.39), the new data revealed. Conversely, Oklahoma had the lowest average gas price at $3.44 per gallon, followed by Kansas ($3.51) and North Dakota ($3.62).
Is premium 93 and 91 the same?
The market mainly offers gasoline with octane ratings of 87, 91, and 93. The difference between them lies in their ability to withstand the internal compression of the engine. Higher octane rating: The engine runs more smoothly and efficiently.