Ethanol Blend Calculator

Mix pump gas and E85 to hit a target ethanol percentage, or calculate the blend from a known mix.

Pump Fuel Type

gallons of 91 octane E10 pump gas

E85 / Ethanol Type

gallons of E85 (typical 78%) (78% ethanol)

Total Volume

15.0 gal

Ethanol Content

E32.7%

Est. Octane (AKI)

95.0

Common Ethanol Blend Targets

E20–E30Conservative flex-fuel tune, good pump gas fallback

E40–E50Moderate flex tune, meaningful octane and power gains

E60–E70Aggressive tune, significantly lower AFR required

E85Full E85 tune, requires flex or dedicated E85 map

E85 ethanol content varies seasonally and by region (typically 70–85%). Always use the actual measured ethanol % if available. Octane estimates use AKI ((R+M)/2) and are approximate.