Pump percentages matter.
High-ethanol fuel can vary. Gasoline commonly contains ethanol too, so use the values for the fuels you’re actually adding.
Free web calculator
Hit your target blend.
Use current fuel and actual pump percentages to plan a full-tank fill.
Plan your fill-up.
This calculator fills the tank to the capacity you enter. Values are U.S. gallons and ethanol percentages.
Your result
Your fill-up plan
High-ethanol fuel to add—
Gasoline to add—
Final tank volume—
Expected blend—
Measured data helps.
If you test pump fuel or have a flex-fuel sensor, use those measured percentages for a better estimate.
Know your vehicle.
This tool calculates a mixture, not vehicle compatibility. Follow manufacturer or tuner requirements.
Want a partial-fill plan?
The iPhone app adds At The Pump partial-fill guidance, saved vehicle defaults, stations, fuel logs, and more.
Open 85Blends on the App Store ↗