This page can be used to approximate octane values when blending pump gasoline with racing fuel to increase average octane. Those who need high octane fuels generally do not need to run straight racing fuel, but rather a blend that is somewhere in-between that and pump gasoline. It is assumed that the octane obtained from mixing fuels will be the simple average of the two.

Your mileage may vary, and it probably will if you start blending your fuel.

Note that this page uses Javascript, and has been known to work correctly in MSIE and Gecko-based browsers. It might work in other browsers if they get their act together.