Quick answers for mixing E85 and pump gas to hit a target ethanol blend. For your exact numbers, use the free calculator.
Open the E85 calculatorHow much E85 do I add to hit my target blend?
It depends on how much fuel is already in your tank and its ethanol content, your tank size, and the ethanol content of both the E85 and the pump gas you're adding. The idea: the ethanol already in the tank, plus the ethanol from the E85, plus the ethanol from the pump gas, has to equal your target percentage of a full tank.
Example: a 12 gallon tank, a quarter full of E10, aiming for E30. That's 3 gallons already in (0.3 gallons of ethanol) and 9 gallons of room. A full tank at E30 needs 3.6 gallons of ethanol, so add 3.2 gallons of E85 and 5.8 gallons of E10.
Why isn't E85 always 85% ethanol?
In the US, fuel sold as E85 can contain anywhere from 51% to 83% ethanol. It changes with the season and region: winter blends usually have less ethanol (often around 70%) so engines start in the cold. If you assume 85% in winter, you'll end up with less ethanol than you planned. Test your fuel with an ethanol content tester when you can.
What does E30 or E50 mean?
The number is the ethanol percentage in your tank: E30 is 30% ethanol, E50 is 50%. Most flex-fuel tunes are set up for a specific blend. Mixing E85 with regular pump gas (usually E10) lets you hit it.
Is it safe to run ethanol blends in my car?
Only run blends your vehicle and tune are set up for. Ethanol needs more fuel than gasoline, so the fuel system and tune have to support it. If you're not sure, ask your tuner before going above E10.
Can I use liters?
Yes. The calculator works in gallons or liters; switch with the Units toggle.
Estimates only. See our Terms of Use.