EV Charging Time Calculator
Calculate how long it will take to charge your electric vehicle based on battery capacity, charger power, and current state of charge.
Formula
Energy Needed (kWh) = Battery Capacity × (Target SOC − Current SOC) / 100
Effective Charge Power (kW) = Charger Power × (Efficiency / 100)
Charging Time (hours) = Energy Needed ÷ Effective Charge Power
Grid Energy Drawn (kWh) = Energy Needed ÷ (Efficiency / 100)
Assumptions & References
- Charging efficiency (default 90%) accounts for heat losses in the onboard charger and cable; real-world values typically range from 85–95% for AC charging and 92–97% for DC fast charging (U.S. DOE).
- Charger power levels: Level 1 ≤ 1.9 kW (120V/16A), Level 2 up to 19.2 kW (240V/80A), DC Fast Charger 20–350 kW (AFDC).
- Battery capacity is the usable (net) capacity, not gross capacity. Many manufacturers quote gross; usable is typically 90–95% of gross.
- This calculator assumes a constant charge rate. In practice, charging slows above ~80% SOC due to battery management system (BMS) tapering.
- Ambient temperature, battery age, and vehicle-specific charge curves can significantly affect real-world charging times.
- Formula reference: Charging Time = (kWh needed) / (charger kW × efficiency) — standard EV charging calculation used by SAE J1772 and IEC 61851 standards.