How much does high-octane fuel cost?
The short answer
In the US, high-octane petrol, usually sold as premium, costs more per gallon than regular at the same station. There is no single fixed price or fixed gap between the grades. Both change from station to station, from region to region, and over time. This article does not include current price data, so the reliable way to get a figure is to compare the posted grade prices at the stations you actually use.
The condition that matters most is your vehicle. If the owner's manual says premium is required, the extra cost is part of running that car. If the manual says regular is fine, paying for premium usually brings no meaningful benefit, so the most useful cost to compare is often zero extra.
What "high octane" means at a US pump
The octane number on a US pump is the Anti-Knock Index, shown as (R+M)/2. It measures how well the fuel resists knock, which is uncontrolled ignition in the cylinder. It does not measure energy content or cleanliness.
Regular: usually 87; Midgrade: usually 89; Premium: usually 91 to 93, depending on the station and region
Some high-altitude areas sell lower-rated regular fuel. If you are comparing grades, check the number posted on the pump rather than relying on the grade name.
Why the price varies
The posted price for any grade reflects local taxes, supply, competition between stations and broader fuel market changes. The gap between regular and premium is set by each retailer, so it can differ between two stations on the same street. A price you saw in one place or at one time does not reliably predict the price elsewhere or later.
How to estimate what premium costs you
The per-gallon gap matters less than what it adds up to over your own driving. You can estimate it with figures from your local pump and your own fuel records:
Extra cost per fill-up = (premium price - regular price) x gallons per fill-up; Extra cost per year = (premium price - regular price) x gallons used per year; Gallons used per year = miles driven per year / your vehicle's miles per gallon
Use the fuel economy you actually get rather than an advertised figure, and redo the calculation when local prices shift noticeably.
Check whether your vehicle needs it
Fuel requirements are set per vehicle and can differ by model year, market, trim and engine, so check the owner's manual or fuel-filler label for your exact car rather than going by the model name alone. Look closely at the wording:
"Premium required": use the stated minimum octane. Lower-octane fuel can cause knock and, depending on the engine, reduced performance or a risk of damage. "Premium recommended": the engine is designed to run on lower octane, usually by adjusting ignition timing through its knock sensors, but may lose some power or efficiency. Whether the gain covers the extra cost depends on your vehicle and driving, and this article has no test data to settle it. "Regular" or 87 octane specified: higher octane generally gives no benefit in power, economy or engine cleanliness, so the extra spend is usually wasted.
What this article cannot tell you
No confirmed prices, price gaps, dates or vehicle-specific test results were available for this guide. It cannot give a current per-gallon price for premium, a typical spread between grades, or a measured fuel-economy difference for any model. For those, use the posted prices at your local stations and the fuel requirement listed for your exact vehicle.
