AKI is simply an average of RON and MON. Two different single cylinder test engine protocols.

There is around 6 or 7 points difference from RON to AKI, but it isn't linear or exact.

98 RON is pretty close to 91 or 92 AKI
95 RON is what we call midgrade, or 89 AKI
91 RON is pretty close to 87 AKI

And ethanol screws them all up.

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