How to use this tool
Enter usable battery capacity, current and target charge, and average wall charging power.
Set wall-to-battery efficiency and electricity price. Advertised peak power may overstate the average; taper and session fees are excluded.
Battery energy = capacity × charge change; wall energy = battery energy / efficiency
Worked example
$8.00 · charging cost
Fixed example using the settings below. Monetary examples use USD; dates and times use their stated reference values. This example stays unchanged when you edit your calculation.
Example inputs
- Usable battery capacity (kWh): 60
- Starting charge (%): 20
- Target charge (%): 80
- Average charging power (kW): 7.2
- Wall-to-battery efficiency (%): 90
- Price per kWh: 0.2
Method illustration: A 60 kWh battery from 20% to 80% adds 36 kWh; at 90% efficiency it draws 40 kWh.
Assumptions and limits
- Enter average power from the wall, not advertised peak. The estimate excludes taper, temperature effects and charging-session fees.
Check or report a result
Check the units, selected calculation and assumptions first. Compare the fixed example above with your inputs to identify what changed.
Report a calculation issue with the page address, hypothetical inputs, result displayed and result expected. Do not include passwords, bank details or other private information.