How to use this Calculator

Use this calculator for these situations:

• You have a completely empty fuel tank, and plan on filling up with a specific ethanol/gas mixture
• You already have an ethanol mixture in the tank, and want to fill up while keeping the same mixture (i.e. you have E30 in the tank and want to add ten more gallons of E30)
• You aren't as concerned with precise mixtures, octane ratings, or need to make any manual adjustments to the fuel specifics

Enter the number of total amount of fuel you need to fill up with in the "Gallons to Fill" box. Then, select your desired mixture in the dropdown - if you have a custom tune from us, we most likely specified something like "E30" or "E50" to use. Now press the "Calculate Mix" button, and the results are displayed to the right. Simply add the amount specified by each fuel type to achieve that mixture.
This calculator also makes the following assumptions:

• Your E85 fuel has an ethanol content of 85%
• Your Gasoline has an ethanol content of 10%

Advanced Calculator

Use this calculator for these situations:

• You already have some gasoline in your tank, and want to add some ethanol to achieve a desired mixture
• You are interested in calculating the estimate octane in different mixture amounts
• Fuel in your area has different ethanol contents - for example, "E85" with 70% ethanol, or pure gasoline with 0% ethanol, etc

For the first (and likely most common) scenario, simply enter the number of gallons of gasoline you think you have in your fuel tank, to your best approximation. Then, add in a number for gallons of ethanol and click the "calculate fuel" button. This will display your specific ethanol mixture - E30, E35, E36, etc. If your desired ethanol mix is lower, decrease the gallons you entered for "E85 Gallons" and click the "calculate fuel" button again. Use this to estimate how much E85 you will need to put in to get the desired mixture.