WattCalc LAB

Time-of-Use EV Charging Calculator

Estimate monthly charging cost and potential savings from moving electric-car charging to a cheaper tariff period.

Typical editable values; verify the exact model year and specification.

kWh
EUR/kWh
EUR/kWh
%

How the calculation works

Estimate monthly charging cost and potential savings from moving electric-car charging to a cheaper tariff period. Change every input to match your vehicle, equipment, tariff or measured consumption.

Scheduled cost = off-peak energy × off-peak price + remaining energy × day price.

Worked example

Moving 90% of 250 kWh monthly charging from €0.30 to €0.16 per kWh reduces the energy charge by about €31.50 per month.

What can change the result?

  • Include taxes and variable network charges in each tariff.
  • Check whether a special tariff adds a fixed monthly fee.
  • Smart charging should still meet the required departure state of charge.

Frequently asked questions

Does the calculator include tariff standing fees?

No. Subtract any additional fixed monthly fee from the displayed saving.

How do I know monthly charging energy?

Use charger records or estimate annual driving energy and divide by 12, including losses.

Can solar charging be included?

Use an effective price for solar energy only if you account for the value of electricity that could otherwise be exported.

Use the result responsibly

This calculator is intended for comparison and planning. Verify equipment limits, tariffs and important electrical decisions with the manufacturer, energy supplier or a qualified professional.