How to use this calculator
Replace the example values with your own measurements or specifications. Keep the units shown beside each label. Results update as you type; reset restores the example.
Efficiency is an assumption; 90% is an editable example, not a guarantee. Use usable battery capacity. Public session fees, idle fees, taxes, and time-based rates are excluded.
The formula
A worked example
A 75 kWh battery charged from 20% to 80% gains 45 kWh. At 90% efficiency it draws 50 kWh. At $0.16/kWh, the session costs $8.00.
Common questions
Why is wall energy higher than battery energy?
Charging has losses, and cooling or heating may use power. Efficiency accounts for these approximately.
Is the electricity rate live?
No. Enter your utility tariff or the charger’s displayed energy rate.
Sources & calculation method
Related guidance: U.S. Department of Energy: EV charging. Accessed September 9, 2026. The equation above describes this tool’s model; the reference provides practical context and does not endorse this site.
Prepared with AI assistance. Formula examples and input validation have automated checks. This page has not received an independent automotive professional review. Read our review standards.