Using the EV Charging Cost Calculator
Use battery consumption in kilowatt-hours per hundred kilometres. Charging efficiency converts that battery requirement into energy drawn from the wall. Enter a comparison vehicle’s fuel economy and fuel price if you also want a simple energy-cost comparison.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Trip distance (km)
- 100
- Battery energy use (kWh / 100 km)
- 15
- Charging efficiency (%) — 90 means 10% loss
- 90
- Electricity price per kWh
- 10
- Comparison vehicle fuel economy (km / litre)
- 15
- Fuel price per litre
- 100
Example result
- Battery energy for trip (kWh)
- 15
- Wall energy incl. losses (kWh)
- 16.666667
- Electricity cost
- 166.66667
- Charging loss (kWh)
- 1.6666667
- Comparable fuel cost
- 666.66667
- Fuel cost minus EV electricity cost
- 500
- Electricity cost per distance unit
- 1.6666667
Method and assumptions
Battery energy = distance × kWh/100km / 100. Wall energy = battery energy / charging efficiency; multiply by tariff for energy cost. Comparison fuel cost = distance / km-per-litre × fuel price. User-supplied tariffs/consumption only. Excludes parking, session fees, time charges, taxes not in tariff, battery wear and temperature effects; this is not total vehicle ownership cost.
Reference: fueleconomy.gov — method and further reading
Use measurements from the same situation
Vehicle and trip estimates are easiest to compare when the inputs refer to the same journey, vehicle or operating condition. Keep the distance unit explicit and separate measured values from planning assumptions. If you change several inputs at once, record which ones changed so that a different result can be traced to a specific assumption.
Common question
Why is wall energy greater than battery energy?
Not all energy taken from the supply reaches the battery. Dividing battery energy by the charging-efficiency fraction accounts for that loss. At ninety percent efficiency, the wall must supply more than one kilowatt-hour to add one kilowatt-hour to the battery.