Ethanol-related Calculators

For the latest E85 prices in your area, visit 

Gas vs E85: cost per mile, cost per year, etc

This calculator calculates the true costs of E85 and gas and will help you determine when the E85 pump is cost-effective.
E85 Price E85 MPG
Gas Price Gas MPG
Miles you drive per year:  
E85 cost per mile:
E85 miles per dollar:
Gas cost per mile:
Gas miles per dollar:
Cost per year, fueled with E85:
Cost per year, fueled with gas:
Gasoline not imported by fueling with E85 (per year):
Reduction in green house gases with E85 (per year):

(You can press the tab key to move between fields)

Blending ethanol and gas

For most vehicles, E10 (10% ethanol) yields worse mileage than gasoline without ethanol. What many people don't know is that E10 is probably the worst blend and for many vehicles, 20-30% ethanol will give you similar mileage to gasoline with no ethanol.1
Enter your gas tank size, previous ethanol %, and how much gas you added and this calculator will tell you the ethanol % in your tank. If you want to just calculate the results of mixing blends, check the "ignore vehicle" checkbox.
Prior to fillingResult
tank (gals) existing % 
0.0% ethanol (or E0)
Gallons added
gals E85*gals E70*gals E30gals E20gals E10gals E0

(You can press the tab key to move between fields)

* Note: in colder areas of the country, the actual percent of E85 gets downgraded to 70% during winter months.2

Octane result from blending 2 fuels

Trying to replace premium gas in a non-flexfuel vehicle? This tool's for you.
Fuel #1 Fuel #2
E85 (Gals)   Gas (Gals)
E85 Octane *   Gas Octane *
% ethanol   % ethanol
Set octane to defaults  Recalculate

* E85 typically has an octane of 105. E10 may vary from 87 to 93. Premium gas typically is 91. Racing fuel is often 100 or higher.3 You should be able to find your octane numbers posted on the gas pump.