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RON vs. MON — What's the Difference?

Edited by Tayyaba Rehman — By Fiza Rafique — Published on October 12, 2023
RON (Research Octane Number) gauges gasoline's anti-knock properties under low-stress conditions, while MON (Motor Octane Number) does so under high-stress conditions.
RON vs. MON — What's the Difference?

Difference Between RON and MON


Key Differences

RON, or Research Octane Number, measures the knock resistance of gasoline in engine conditions mirroring low-speed and low-load driving. In contrast, MON, standing for Motor Octane Number, evaluates this resistance under conditions reminiscent of high-speed and high-load driving scenarios.
Both RON and MON provide valuable insights into gasoline's performance. While RON evaluates fuel performance more in line with regular, city driving situations, MON addresses performance under demanding conditions, such as highway speeds or towing. Their ratings help fuel producers and regulators ensure fuel quality and compatibility with various engine types.
It's important to recognize that while RON and MON are both octane ratings, they're obtained through different testing methods. RON testing is performed at lower engine speeds, focusing on conditions that most drivers might encounter daily. Conversely, MON testing subjects fuel to high temperatures and RPMs, simulating challenging driving scenarios.
For consumers, both RON and MON ratings might appear on gasoline pumps, often averaged as an "anti-knock index" or AKI. This combined number helps drivers choose the right gasoline for their vehicles. Both RON and MON remain pivotal in the fuel industry, ensuring engines run smoothly and efficiently across varied driving conditions.

Comparison Chart


Research Octane Number
Motor Octane Number

Test Conditions

Low stress (e.g., low speeds)
High stress (e.g., high speeds)


Reflects city driving scenarios
Reflects highway or challenging scenarios

Typical Use

Everyday driving conditions
Demanding driving conditions

Consumer Visibility

Often part of AKI on gasoline pumps
Often part of AKI on gasoline pumps

Compare with Definitions


A rating measuring gasoline's anti-knock properties under low stress.
The RON value indicates how well the fuel might perform in city driving.


Assesses gasoline's anti-knock properties under high stress.
The MON rating indicates potential fuel performance during high-speed driving.


Pertains to Research Octane Number.
A high RON value suggests better resistance to knocking during regular driving.


Testing involves high temperatures and speeds.
MON tests subject fuel to more severe conditions than RON tests.


Evaluates gasoline under low-speed conditions.
RON testing is vital for assessing fuel for daily commuting.


Also part of the Anti-Knock Index in the USA.
Along with RON, MON helps determine the AKI value seen on pumps.


Commonly seen in European gasoline ratings.
In Europe, gasoline might be labeled with a RON rating of 95.


Relevant for challenging driving scenarios.
MON values are essential for performance cars that operate at high RPMs.


Part of the Anti-Knock Index (AKI) in the USA.
The AKI value is an average of the RON and MON values.


A member of a traditionally Buddhist people inhabiting eastern Myanmar (Burma) and adjacent parts of Thailand.


(slang) heroin


The Mon-Khmer language of the Mon.


A Chadic language spoken in northern Nigeria




(historical) The former currency of Japan until 1870, before the yen.


The badge or emblem of a Japanese family, especially a family of the ancient feudal nobility; typically circular and consists of conventionalized forms from nature.


A colloquial means of address of man in places such as Jamaica and Shropshire in England.


(fandom) A creature in a video game, usually one which is captured, trained up and used in battles.


(fandom) A video game or anime in which catching and battling creatures is an important element.


The badge of a family, esp. of a family of the ancient feudal nobility. The most frequent form of the mon is circular, and it commonly consists of conventionalized forms from nature, flowers, birds, insects, the lightnings, the waves of the sea, or of geometrical symbolic figures; color is only a secondary character. It appears on lacquer and pottery, and embroidered on, or woven in, fabrics. The imperial chrysanthemum, the mon of the reigning family, is used as a national emblem. Formerly the mon of the shoguns of the Tokugawa family was so used.


The second day of the week; the first working day


A member of a Buddhist people living in Myanmar and adjacent parts of Thailand


The Mon-Khmer language spoken by the Mon people


Stands for Motor Octane Number.
A fuel with a high MON value resists knocking under demanding conditions.

Common Curiosities

What does RON stand for?

RON stands for Research Octane Number.

How does MON differ from RON?

MON measures gasoline's anti-knock properties under high-stress conditions, while RON does so under low-stress conditions.

Why are both RON and MON important for gasoline?

They help determine gasoline's performance under different driving conditions.

How are RON and MON used in the USA's AKI rating?

AKI is the average of the RON and MON values.

When might MON be more relevant than RON?

MON is crucial for scenarios involving high speeds or towing, often resembling highway driving.

Is RON more relevant for city driving?

Yes, RON reflects gasoline performance under conditions similar to city driving.

Can using the wrong RON or MON gasoline damage my engine?

Using a lower than recommended octane can lead to engine knocking, which might cause damage over time.

Why is there a difference between RON and MON values for the same fuel?

The two tests simulate different driving conditions, leading to different results for the same fuel.

How are RON and MON tested?

They're determined using different test methods, with RON testing under low-stress and MON under high-stress conditions.

Are RON and MON values typically the same for a gasoline type?

No, MON values are generally lower than RON values for the same gasoline.

Are higher RON and MON values always better?

Higher values indicate better resistance to knocking, but it's essential to use the fuel grade recommended for your vehicle.

Why do some countries focus more on RON ratings at pumps?

RON is more indicative of everyday driving conditions, especially relevant in regions with predominantly urban driving.

How do I know the RON or MON rating of the gasoline I'm buying?

Some countries label pumps with RON, MON, or AKI values. Check the pump or ask the fuel station.

Are RON and MON the only octane ratings used globally?

While RON and MON are common, other regions might use different standards or a combination.

Does premium gasoline always have higher RON and MON values?

Generally, premium gasoline has higher octane values, but it's always best to check the specific ratings.

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Author Spotlight

Written by
Fiza Rafique
Fiza Rafique is a skilled content writer at, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Tayyaba Rehman is a distinguished writer, currently serving as a primary contributor to As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.

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