Ethanol Fuel Mixture Calculator
Use this calculator to determine how much gasoline and E85 ethanol to add to your gas tank to top it off to a desired ethanol percentage.
2015-2021 WRX Tank Size 15.9 gal
2022+ Wrx Tank Size 16.6 gal
What’s In Your Gas Tank?
Please input the size of your fuel tank in the first box. In the second box, enter the fuel level of your car. If it's in the middle, it would be 50%, quarter tank would be 25%, and so forth. In the final box, enter the content of the fuel that is in your tank. If you are running E60, enter E60. If you are running 91/93, most of this fuel contains 10% ethanol, so enter 10. If you are using ethanol-free fuel, enter 0.
Tank Size (gals)
Fuel Level %
Fuel Ethanol %
What’s Your Desired Result?
Please enter your desired ethanol blend in the first box. If you prefer E30, enter it here. If you prefer E60, enter that instead. In the second box, please input the percentage of ethanol content in the fuel, for example, if the ethanol you are pumping is tested at E76, enter 76. If the ethanol level is precisely 85, enter that number here. In the final box, enter the content of the fuel you are mixing with. Usually, this is 10, which is the percentage of ethanol in standard E10 91/93 fuel. If you are using ethanol-free fuel, enter 0.
Desired Ethanol %
* Typical values are 30, 60, or 85 percent.
E85 Ethanol %
* E85 Ethanol content can vary.
from pump to pump and fill up to fill up. HIGHLY suggest getting a cheap testing kit. Click here for the one we suggest!
Gas Ethanol %
* Most 91/93 fuel contains 10% ethanol.
Fuel Mixing Instructions
***If it says to fill 0.00 gallons of either fuel, that means that you have too much fuel in your tank and it is NOT currently possible to reach your desired ethanol blend you will need to drain fuel or drive more to use more of the fuel in tank to make this target blend possible ( Thanks Clint S for the tip to add this)
Fill out the form above and press CALCULATE to get your fuel mixing instructions.**