Inputs
Start with the numbers you know.
- Enter current fuel amount, current ethanol, target ethanol, and fill amount.
- Use manual values when you want to plan a one-off fill.
- Review every value before using the result.
Ethanol calculator
Estimate your ethanol blend before you fill up.
Idle helps iPhone drivers plan E85 blends from the current fuel, target ethanol, fill amount, and saved garage vehicle details they enter.
Fuel math
A cleaner way to plan the blend.
The calculator keeps the numbers close to your garage and fuel tools, so you can plan before the stop instead of doing the math in scattered notes.
Garage defaults
Use saved fuel details when they help.
- Save tank size, pump gas, ethanol defaults, and notes for your own garage vehicles.
- Update saved values when your setup, tune, or fuel plan changes.
- Keep build-specific fuel notes with the vehicle they belong to.
Before you drive
Treat the result as a planning estimate.
- Confirm station details, fuel availability, and hours before driving.
- Only use blends your vehicle, tune, and parts support.
- When something looks off, check the numbers before filling up.
Questions
Ethanol calculator questions.
Short answers for drivers searching for an ethanol calculator, E85 calculator, or fuel blend calculator for their build.
Idle's ethanol calculator estimates blend amounts from the current fuel, current ethanol, target ethanol, fill amount, and vehicle defaults you enter.
Yes. You can save useful fuel details for your own garage vehicles, such as tank size, pump gas, ethanol defaults, and notes, then use them when planning a blend.
No. The calculator is a planning tool from your inputs. Only use blends your vehicle, tune, and parts support.
No. Confirm station details, fuel availability, and hours before driving.
Plan fuel blends in Idle.
Download Idle for iPhone to estimate ethanol blends, look for nearby E85 stops, save garage fuel details, and find meets around the local car scene.