Choose what you're trying to do

• Mix a fresh tank: use this when the tank is empty or nearly empty and you want to make a new E30, E50, E85, or custom mixture.
• Add to what's in my tank: use this when fuel is already in the vehicle and you want the finished tank to reach a specific ethanol percentage.
• Fix my current blend: use this when your current ethanol percentage is too high or too low.
• Just give me the ratio: use this when you only want the percentage or ratio of E85 to pump gasoline.

Select your target ethanol blend

Choose the ethanol percentage required by your calibration.

If your tune specifies E50, select E50. Do not select a different ethanol percentage simply because higher ethanol is available.

Choose your tank size and final fuel amount

Select your fuel tank capacity from the common Ford sizes or choose Other / Enter my tank size.

• Choose Fill the tank if you plan to fill to the selected tank capacity.
• Choose Specific amount if you only want a certain total amount of fuel when finished.
• If you do not know the tank size, use the Ford tank-size guide below.

Tell the calculator what's already in the tank

This step appears when existing fuel needs to be included.

• Use Use fuel gauge and drag the slider to approximately match your fuel gauge.
• Use Enter gallons if you know the amount remaining more accurately.
• Choose whether the current fuel is Pump Gas / E10, E30, E50, E85, or Other.
• Select Other to enter an exact current ethanol percentage such as E37.

Enter the fuel available at the pump

The calculator defaults to E85 for the high-ethanol fuel and E10 for pump gasoline.

• If your tested E85 measures E72, change the E85 field from 85 to 72.
• If you did not test the E85, leave the default at 85 and treat the result as an estimate.
• If your gasoline has a different ethanol percentage than E10, change that value too.

Calculate your mix

Select Calculate My Mix. The result will show:

• Gallons of E85 to add
• Gallons of pump gasoline to add
• Estimated final ethanol percentage
• Final fuel quantity
• Rounded pump-friendly amounts
• The estimated blend produced by those rounded amounts

If the requested blend cannot be made

Sometimes there is too much fuel already in the tank, the existing ethanol percentage is too high, or the available fuels cannot reach the requested target.

The calculator will explain the issue. When possible, Fix my current blend can determine how much fuel needs to be removed and replaced.