Is petrol the same as gasoline?

Yes—petrol and gasoline are the same type of fuel used in spark-ignition internal combustion engines; the difference is primarily linguistic: “petrol” is the common term in the UK and much of the Commonwealth, while “gasoline” (or simply “gas”) is used in the United States and Canada. In practice, blends and labeling can vary by country due to different standards, octane rating systems, ethanol content rules, and seasonal formulations.

What the terms mean and where they’re used

“Petrol” and “gasoline” both refer to refined petroleum distillates designed for use in cars, motorcycles, and small engines with spark ignition. The terminology follows regional conventions: petrol in the UK, Ireland, India, Australia, New Zealand, South Africa, and much of Asia and Africa; gasoline/gas in the U.S., Canada, and parts of Latin America (though many Latin American countries also use “gasolina”). Despite the naming differences, these words point to the same general product category.

How they can still differ in practice

While the words are synonymous, local laws and market preferences shape the fuel you actually pump. These differences include allowable additives, volatility limits for hot or cold weather, ethanol blending percentages, and how octane is measured and displayed to consumers.

Standards and technical specifications

The following list outlines the major standards that define gasoline/petrol quality in different regions and what they typically cover.

• United States: ASTM D4814 sets requirements for volatility, distillation, oxygenates (such as ethanol), and detergents.
• European Union and UK: EN 228 (branded in the UK as BS EN 228) governs unleaded petrol, including sulfur limits, oxygenates, and vapor pressure; the UK mirrors EU norms post-Brexit with domestic statutory instruments.
• India: BIS IS 2796 specifies automotive gasoline, including octane minimums and ethanol allowances (E5/E10 depending on rollout and availability).
• Australia: Fuel Quality Standards (Petrol) Determination sets parameters similar to EN 228/ASTM D4814, including sulfur caps and aromatics limits.

These standards produce broadly compatible fuels for modern vehicles, but the exact blend you buy in one country may not be identical to another due to environmental policies and local performance needs.

Octane numbers and labeling

Octane indicates resistance to engine knock. The same physical fuel can be labeled differently depending on the measurement system in a given market.

• Europe/UK/Most of the world: Labels typically show RON (Research Octane Number). Common grades are 95 RON (“unleaded”), 97–99 RON (“super” or “premium”).
• United States/Canada: Pumps display AKI (Anti-Knock Index), also called (R+M)/2, which averages RON and MON. Typical grades: 87 AKI (≈ 91–92 RON), 89 AKI (≈ 94–95 RON), 91–93 AKI (≈ 95–98 RON) for premium.
• “Premium” is not a universal octane number; it varies by country. Always match the vehicle manufacturer’s recommendation.

Understanding the labeling system matters when traveling: a vehicle needing 95 RON in Europe generally corresponds to about 91 AKI in the U.S.

Ethanol and alternative blends

Many countries blend ethanol into petrol/gasoline to cut emissions, support biofuels, or improve octane. The letter “E” followed by a number denotes the ethanol percentage.

• E0: No ethanol; less common in urban areas but available for marine/small engine use in some markets.
• E5/E10: Up to 5% or 10% ethanol; standard in much of Europe and the UK (E10 became the UK’s standard petrol in 2021, with E5 sold as a “protection grade”).
• United States: E10 is widespread; E15 is approved for most 2001+ cars and, as of 2025, has year-round sales in several Midwest states under an EPA rule, with broader seasonal waivers in some years.
• Brazil: Common gasoline (“Gasolina C”) contains about 27% ethanol (E27), a long-standing national standard.
• E85: Mostly ethanol, for Flex-Fuel Vehicles only; not suitable for standard engines unless specifically approved.

Before using higher-ethanol blends, confirm your vehicle’s compatibility; small engines, classics, and certain motorcycles may require low-ethanol fuel or specific storage practices.

Seasonal and regional volatility differences

Refiners alter volatility to ensure reliable starting and drivability across temperatures and altitudes, especially for emissions control.

• Summer vs. winter blends: Lower vapor pressure in summer reduces evaporative emissions; higher in winter aids cold starts.
• Regulated zones: In the U.S., Reformulated Gasoline (RFG) rules apply in certain metro areas; similar climate/air-quality driven rules exist in other regions.
• Altitude: High-elevation markets may adjust blends to local conditions.

These seasonal and regional tweaks don’t change the basic identity of petrol/gasoline but can affect how a vehicle feels in different places and times of year.

What petrol/gasoline is not

Because “gas” can refer to different fuels in everyday speech, it’s important to distinguish what petrol/gasoline is not.

• Not diesel: Diesel fuel is for compression-ignition engines and must not be used in petrol/gasoline engines (and vice versa).
• Not LPG/autogas or CNG: These are gaseous fuels (propane-butane blends or compressed natural gas) and require different fueling systems.
• Not aviation gasoline (avgas): Avgas (e.g., 100LL) is leaded and formulated for aircraft piston engines; it’s not for road vehicles.
• Not “white gas”/camp fuel: Also called Coleman fuel or naphtha; it’s a different light hydrocarbon mixture used in stoves and lanterns.

Using the wrong fuel can damage engines or emissions systems, so always verify the intended fuel type for your equipment.

Practical implications for drivers and equipment

For everyday use, here are the key points that determine what you should pump, regardless of whether the pump says petrol or gasoline.

• Treat “petrol” and “gasoline” as interchangeable terms, but match the octane rating your vehicle requires.
• Check ethanol compatibility: Many modern cars handle E10 without issue; E15 or higher requires explicit approval (Flex-Fuel for E85).
• Small engines and classics: Prefer E0 or E5 where possible, or use stabilizers and compatible hoses/seals to mitigate ethanol effects.
• Traveling abroad: Convert octane labels (RON vs. AKI) to meet your engine’s spec; don’t assume “premium” means the same everywhere.
• Avoid misfueling: Petrol/gasoline is distinct from diesel, LPG/autogas, CNG, avgas, and camping fuels.

Following the manufacturer’s fuel and octane guidance—and being mindful of ethanol content—will ensure performance and protect warranties across regions.

Bottom line

Petrol and gasoline are the same kind of road fuel, differentiated mainly by regional vocabulary. The real-world differences you’ll encounter are about standards, octane labeling, ethanol content, and seasonal blends—not a fundamental distinction in what the fuel is.

Summary

Petrol equals gasoline: they’re two names for the same spark-ignition engine fuel. Expect regional variations in specifications (ASTM vs. EN 228), octane labels (AKI vs. RON), ethanol blends (E5/E10, with E15 and E27 in some markets), and seasonal volatility. Use the octane your vehicle specifies, confirm ethanol compatibility, and don’t confuse petrol/gasoline with diesel, LPG/CNG, avgas, or camping fuels.