[Tagging] Fuel octane ratings: RON versus AKI

Minh Nguyen minh at nguyen.cincinnati.oh.us
Sat Jul 20 00:24:57 UTC 2019

This week's weeklyOSM [1] included a suggestion to minimize the number 
of fuel:* subkeys, which reminded me that the fuel tagging situation in 
the United States is actually quite complicated. The same generic grade 
of gasoline ("regular", "mid-grade", "premium") may have a different 
octane rating at one gas station than the station across the street, and 
each state has a different standard for the minimum octane that may be 
labeled with a particular grade. [2] What would be sold as premium 
gasoline in Alaska would be regular in South Carolina.

Compounding the matter, for several years, the fuel:* wiki page has 
specified that octane ratings must be expressed in RON, which is used in 
more countries. [3] In a few countries including U.S., octane ratings 
are only posted in RON, not AKI. Converting between AKI and RON would 
require knowing the MON, which AFAICT isn't published anywhere. 
Wikipedia does offer estimates for regular and premium grade, but they 
aren't reliable or specific enough to use as subkeys. [4]

I've updated the wiki page with statistics demonstrating that octane 
ratings are consistently mapped based on AKI in the U.S. [5] (If I'm 
wrong about this, then OSM is a better resource for finding unlawful 
stations than lawful stations.) It stands to reason that mappers would 
tag what they can plainly see rather than learn the intricacies of 

 From a data consumer's perspective, it's unfortunate that there's no 
single worldwide standard. But I think more data consumers would need to 
differentiate between different grades in the same region than across 
national boundaries. If we do want to remove the current ambiguity, we 
could define separate fuel:ron_* and fuel:aki_* subkeys, but that seems 
like a lot of work for little gain.

[1] http://weeklyosm.eu/archives/12232
[2] https://en.wikipedia.org/wiki/U.S._State_Fuel_Octane_Standards
[3] https://wiki.openstreetmap.org/wiki/Special:Diff/1033280
[4] https://en.wikipedia.org/wiki/Octane_rating#Measurement_methods
[5] https://wiki.openstreetmap.org/wiki/Key:fuel#United_States

minh at nguyen.cincinnati.oh.us

More information about the Tagging mailing list