Charging cost calculator
Estimate electricity only. Enter your own tariff; no national price is assumed.
Enter your tariff and calculate.
Use the energy rate from your own bill
Enter your electricity price per kWh, including any per-kWh components you want represented. The example uses US dollars, but the multiplication works in any currency when you interpret the result in the same currency as the tariff entered. Do not enter the whole monthly bill or a price per MWh.
For time-of-use rates, model sessions separately if they occur at different prices. A single blended rate is an assumption. Fixed service charges and charges based on peak demand are not estimated by this tool.
Describe the charge session
Use nominal Wh, the assumed capacity factor, and the start and target percentages. Charging efficiency converts the energy stored in the battery into energy drawn from the wall. Do not subtract another reserve: the start-to-target interval already defines the energy change.
Wall kWh = nominal Wh × capacity factor × (target charge − starting charge) ÷ charging efficiency ÷ 1,000. Energy cost = wall kWh × tariff per kWh.
Worked example
A 1,000 Wh battery at 100% assumed health charged from 20% to 100% at 80% charging efficiency uses 1.00 kWh from the wall. At an illustrative $0.20/kWh, the energy costs $0.20. This tariff is an example, not a current electricity price.
Calculated with the same formulas as the interactive tool. Inputs are illustrative and results are rounded for display.
What is excluded?
This estimates the energy for the modeled battery charge. It excludes equipment purchase, battery depreciation, standby outside the session, taxes or fees not included in your input, and simultaneous appliance consumption. If a load runs while charging, the wall meter can record more energy than this estimate.
Why might a measured charge differ?
The capacity factor, charge indicator, charging efficiency, and session boundary are simplified assumptions. A plug-in energy measurement over a comparable charge session can help you assess them. See the measurement guide for keeping the measurement boundary clear.