How to use this Ethanol Calculator
- Input how many gallons of gas your car holds (see common tank sizes below)
- Enter the ethanol content from the pump gas you will be using in this mixture. The ethanol content of 91oct coming from the gas station typically has an ethanol content of 9.8%.
- Enter the ethanol content from the E85 gas you will be using in this mixture. The ethanol content of the E85 coming from the gas station will vary throughout the year. In the summer months (May-September), when it’s always above freezing, you will typically find 78-83%. In the winter months (October-April), you will typically find 68-72%. It is not very common to find E85 that is actually 85% here in Minnesota.
- Enter your target ethanol mix.
- Enter your current fuel tank level – i.e., if you have a quarter tank left, that’s 25%.
- Lastly, enter the ethanol content of the fuel currently in your gas tank.
Gas tank sizes for common vehicles are as follows:
- Subaru WRX/STI (all years) – 15.9 gallons
- Evo 8/Evo 9 – 14 gallons
- Evo X – 14.5 gallons