How it works
How to calculate it
The calculator applies the values you enter to this formula:
Grid energy = miles ÷ vehicle efficiency ÷ charging efficiency; cost = grid energy × rate.
How to use this calculator
- Enter miles driven for one period.
- Use observed miles per kWh.
- Include charging efficiency and the rate paid at home.
Worked example
Driving 1,000 miles at 3.5 mi/kWh with 90% charging efficiency requires about 317 kWh from the grid.
Important assumptions
- Vehicle efficiency is the driving average.
- Charging losses are represented by the efficiency input.
- Time-of-use rates, public charging, and fixed utility fees are excluded.
Common mistakes to avoid
- Ignoring charging losses.
- Using ideal vehicle efficiency.
- Mixing home and public charging prices.
Method reviewed June 10, 2026. Prices and rates are user-provided defaults and should be replaced with local values.